Two manganese phosphonates Mn3（4-piH）2（H2O）3·H2O （1） and Mns（4-piH）2（4-piH2）2（phen）2（H2O）4 （2） （4-pill4 = 4-phosphonoisophthalic acid, phen = 1,10-phenanthroline） have been synthesized under hyd...Two manganese phosphonates Mn3（4-piH）2（H2O）3·H2O （1） and Mns（4-piH）2（4-piH2）2（phen）2（H2O）4 （2） （4-pill4 = 4-phosphonoisophthalic acid, phen = 1,10-phenanthroline） have been synthesized under hydrothermal conditions in the pres- ence of organic co-ligand. Both compounds exhibit layer structures but with different topologies. In compound 1, a complicated ＂ladder-like＂ chain of {Mn3O3}O2 which contains three- and six-member rings made up of triangular shaped {Mn3O3} tri- mers is found. The chains are linked by the PO3C groups to form an inorganic layer. The phenyl and protonated carboxylate groups are pendent between the layers with extensive hydrogen bonds. In compound 2, tetramers of {MnnO6 } are connected by the { MnO6 } octahedra through corner-sharing to form an infinite chain, which is further bridged by 4-pill3- ligands into a thick hybrid layer. Magnetic measurements reveal that antiferromagnetic interactions are dominant in both compounds. Metamag- netism is observed in compound 1 at low temperature, while no long range ordering is found in compound 2 down to 1.8 K.展开更多
A cyanide-bridged Fei^III2Coll double zigzag chain, { [Fen1（bipy）（CN）4]2Con（btab）2}n [bipy=2,2＇-bipyridine, btab=4,4＇-（1,3-phen- ylene）-bis-4H-1,2,4-triazole] （1）, was obtained with tetracyanometalate prec...A cyanide-bridged Fei^III2Coll double zigzag chain, { [Fen1（bipy）（CN）4]2Con（btab）2}n [bipy=2,2＇-bipyridine, btab=4,4＇-（1,3-phen- ylene）-bis-4H-1,2,4-triazole] （1）, was obtained with tetracyanometalate precursors and Con ions. The chains were further linked by the ditopic btab ligands to a layer. Magnetic property studies demonstrate that 1 shows both metamagnetism with a critical field He=400 Oe and single-chain magnet behavior.展开更多
This study presents an experimental investigation of the coupled caloric effect driven by dual-fields in metamagnetic alloy ErCo_(2) with strong magneto-structural coupling.Magnetic measurements were conducted under d...This study presents an experimental investigation of the coupled caloric effect driven by dual-fields in metamagnetic alloy ErCo_(2) with strong magneto-structural coupling.Magnetic measurements were conducted under different pressures,revealing that the application of hydrostatic pressure stabilizes a small volume of paramagnetism(PM) phase,resulting in a shift of the phase transition temperature towards the low-temperature region.This shift is opposite to the temperature associated with the magnetic field-driven phase transition.As pressure increases,the metamagnetic transition in ErCo_(2) is suppressed,and the hysteresis disappears.However,the produced cross-coupling caloric effect compensates the decrease in entropy change caused by the disappearance of the metamagnetic transition.As a result,a reversible giant magnetocaloric effect of 46.2 J/(kg·K) without hysteresis is achieved at a pressure of 0.910 GPa.Moreover,we propose that the temperature span of ErCo_(2) can be significantly widened by optimizing the thermodynamic pathway of the magnetic and pressure fields,overcoming the defect of a narrow temperature range.展开更多
The exploration and synthesis of new materials are important for materials science and condensed matter physics.Here, we report the crystal structure, magnetic properties, and electrical transport properties of the si...The exploration and synthesis of new materials are important for materials science and condensed matter physics.Here, we report the crystal structure, magnetic properties, and electrical transport properties of the single crystals of Nd_(5)ScSb_(12), which is a quasi-one-dimensional new compound. Nd_(5)ScSb_(12) exhibits antiferromagnetic transition in both directions perpendicular and parallel to the long axis. Moreover, the magnetic field-dependent magnetization reveals two metamagnetic transitions. The electrical transport properties have been measured on the same sample but with different measurement lengths between the electrodes of the voltage. The resistivity exhibits the metallic behavior. At low temperatures, the Kondo effect and negative transverse magnetoresistance(MR)(B⊥I) have been observed. Interestingly, the measurement length has a significant impact on the Kondo effect and negative MR, providing an intuitive new approach to regulate the Kondo effect. As the measurement length increases, the Kondo effect and negative MR become more pronounced. This not only indicates that the interaction between magnetic impurities and conduction electrons dominates the electrical transport of Nd_(5)ScSb_(12) at low temperatures, but also confirms that the negative MR originates from the suppression of the Kondo effect.展开更多
The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental analysis.Based on the first principl...The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental analysis.Based on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was investigated.The experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 K.The magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and discussed.The values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,respectively.As a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.展开更多
The dynamic magnetic behavior of the kinetic metamagnetic spin-5/2 Blume-Capel model is examined, within a mean-field approach, under a time-dependent oscillating magnetic field. To describe the kinetics of the system...The dynamic magnetic behavior of the kinetic metamagnetic spin-5/2 Blume-Capel model is examined, within a mean-field approach, under a time-dependent oscillating magnetic field. To describe the kinetics of the system, Glauber- type stochastic dynamics has been utilized. The mean-field dynamic equations of the model are obtained from the Master equation. Firstly, these dynamic equations are solved to find the phases in the system. Then, the dynamic phase transition temperatures are obtained by investigating the thermal behavior of dynamic sublattice magnetizations. Moreover, from this investigation, the nature of the phase transitions （first- or second-order） is characterized. Finally, the dynamic phase diagrams are plotted in five different planes. It is found that the dynamic phase diagrams contain the paramagnetic （P）, antiferromagnetic （AF5/2, AF3/2, AF1/2） phases and five different mixed phases. The phase diagrams also display many dynamic critical points, such as tricritical point, triple point, quadruple point, double critical end point and separating point.展开更多
Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when...Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic （IEM） transition above Tc becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg·K as the field changes from 0 to 5T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.展开更多
An intrinsic two-way shape memory effect with a fully recoverable strain of 1.0%was achieved in an as-prepared Ni50Mn37.5Sn12.5 metamagnetic shape memory microwire fabricated by Taylor-Ulitovsky method.This two-way sh...An intrinsic two-way shape memory effect with a fully recoverable strain of 1.0%was achieved in an as-prepared Ni50Mn37.5Sn12.5 metamagnetic shape memory microwire fabricated by Taylor-Ulitovsky method.This two-way shape memory effect is mainly owing to the internal stress caused by the retained martensite in austenite matrix,as revealed by transmission electron microscopy observations and highenergy X-ray diffraction experiments.After superelastic training for 30 loading/unloading cycles at room temperature,the amount of retained martensite increased and the recoverable strain of two-way shape memory effect increased significantly to 2.2%.Furthermore,a giant recoverable strain of 11.2%was attained under a bias stress of 300 MPa in the trained microwire.These properties confer this microwire great potential for micro-actuation applications.展开更多
The FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites were prepared by hot pressing(HP). The microstructure,corrosion behavior and magnetocaloric effect(MCE) of FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites were investiga...The FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites were prepared by hot pressing(HP). The microstructure,corrosion behavior and magnetocaloric effect(MCE) of FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites were investigated systematically. The results show that the corrosion resistance of FeNi coated LaFe_(11.6)Si_(1.4)Sn composites is better than that of LaFe_(11.6)Si_(1.4)/Sn composites in deionized water. The maximum magnetic entropy change((-△S_M)^(max)) and relative cooling power(RCP) of FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites are 13.30 J/(kg-K) and 146.25 J/kg, respectively, which are larger than that((-△S_M)^(max), 10.65 J/(kg·K) and RCP, 106.53 J/kg) of LaFe_(11.6)Si_(1.4)/Sn composites in a low magnetic field change of 2 T. FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites possess a more negative slope. The improvement of magnetic properties is due to high permeability FeNi permalloy(1 J85) which improves the itinerant-electron metamagnetic(IEM) transition. So, the method of coating FeNi can provide a new idea for enhancing the corrosion resistance and magnetocaloric effect of La(Fe_xSi_(1-x))_(13)-based materials.展开更多
The Ni43.75Mn37.5In12.5Co6.25 alloy was obtained by using the spark plasma sintering(SPS)technique.The martensitic transformation,magnetic and mechanical properties of the SPS alloy were investigated.Key findings demo...The Ni43.75Mn37.5In12.5Co6.25 alloy was obtained by using the spark plasma sintering(SPS)technique.The martensitic transformation,magnetic and mechanical properties of the SPS alloy were investigated.Key findings demonstrate that the martensitic transformation temperature of this alloy is about 10 K lower than that of the as-cast one.Both SPS and as-cast alloys show a 7 layered modulated martensite(7M)at room temperature.The compressive fracture strength and strain of the SPS alloy increase by 176.92%and 33.33%compared with the as-cast alloy,achieving 1440 MPa and 14%,respectively.The maximum magnetic entropy change Smis 17.1 J kg^(-1)K^(-1)for the SPS alloy at the magnetic field of 5 T.展开更多
The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably, resulting in the magnetost...The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably, resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil_χFexGe alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe, metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil-xFezGe alloys at temperature below the structural transition temperature.展开更多
Crystal structure, magnetic properties and magnetocaloric effects （MCE） of La1-xBixFe1 1.4Si1.6 （x=0.0 and 0.1） compounds were investigated by X-ray diffraction and magnetization measurements. The La1-xBixFe11.4Si...Crystal structure, magnetic properties and magnetocaloric effects （MCE） of La1-xBixFe1 1.4Si1.6 （x=0.0 and 0.1） compounds were investigated by X-ray diffraction and magnetization measurements. The La1-xBixFe11.4Si1.6 compounds presented a cubic NaZnx3 type structure. First, the magnetization behavior and the magnetic transition were analyzed in terms of Landau theory. Then, Bi substitution for La in La1-xBixFe11.4Si1.6 compounds led to a decrease in magnetic entropy change （-△SM^max） but an increase in Curie temperature （Tc） significantly. The significant increase of Tc by Bi substitution from 202.5 to 256 K for x=0.0 and x=0.1 respectively was attributed to an increase in the Fe-Fe exchange interactions. Moreover, magnetocaloric effect was calculated in terms of isothermal magnetic entropy change. The maximum values of （-△SM^max ） of La1-xBixFe11.4Si1.6 for x=-0.0 and 0.1 compounds were found to be, respectively, 22.56 and 4.36 J/（kg.K） under an applied magnetic field change of 5 T. For the same applied magnetic field （μ0H=5 T）, the relative cooling power （RCP） values were found to vary between 487 and 296 J/kg.展开更多
A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_...A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.展开更多
The isothermal section of the Ho-Fe-In system at 773 K has been constructed by X-ray powder diffraction.One known structure ternary compound Er_(12)Fe_(2) In_(3)-type Ho_(12)Fe_(2) In_(3) has been confirmed.At the sam...The isothermal section of the Ho-Fe-In system at 773 K has been constructed by X-ray powder diffraction.One known structure ternary compound Er_(12)Fe_(2) In_(3)-type Ho_(12)Fe_(2) In_(3) has been confirmed.At the same time,solid solutions are not detected in Ho-Fe-In system at 773 K.The magnetic transition and magnetocaloric effect of Ho_(12)Fe_(2.08)In_(2.92) alloy with Er_(12)Fe_(2) In_(3)-type structure were investigated by magnetic susceptibility and isothermal magnetization measurements.One normal antiferromagnetic-paramagnetic transition and another abnormal one are discovered at 18 and 76 K in ground state,respectively.Owing to a first-order field-induced metamagnetic transition(antiferromagnetic-ferromagnetic) at/below the Neel temperature of 18 K),the negative entropy changes are observed at corresponding temperature.There is only a second-order ferromagnetic-paramagnetic transition near Curie temperature(TC),the maximum entropy change(Δ_(Smax)) values are-6.14 J·kg^(-1)·K^(-1) at 3 K and 7.88 J·kg^(-1)·K^(-1) at 28 K in a field range of 0-7 T.The reversible relative cooling power corresponding to negative entropy change can reach about 600 J·kg^(-1) in an wide operating temperature region Δ_(Tcycl)=74 K from 16 to90 K,which suggests that Ho_(12)Fe_(2.08)In_(2.92) could be a potential material for magnetic refrigeration in the corresponding temperature range.展开更多
The new scheelite form of SmCrO4 oxide was obtained by heating the zircon-type SmCrO4 oxide at 4 GPa and 803 K. X-ray diffraction revealed that this scheelite SmCrO4 phase crystallized with tetragonal symmetry, S.G. I...The new scheelite form of SmCrO4 oxide was obtained by heating the zircon-type SmCrO4 oxide at 4 GPa and 803 K. X-ray diffraction revealed that this scheelite SmCrO4 phase crystallized with tetragonal symmetry, S.G. I41/a and lattice parameters: a=0.50776(3) nm and c=1.15606(2) nm. This structural phase transition from zircon to scheelite involved a decreasing of around 10% in the unit cell volume. Although the Cr-O and Sm-O distances did not change very much in both zircon and scheelite polymorphs, the changes occurred in the bond angles were remarkable that appear to support the proposed reconstructive model to explain this structural zircon-scheelite phase transition. Magnetic susceptibility and magnetization measurements revealed that the scheelite SmCrO4 oxide behaved an antiferromagnetic material, where the Sm3+ and Cr5+ were simultaneously ordered. The estimated Néel temperature, TN, was 16 K and the critical field at 12 K associated with the metamagnetic transition was 3.2 T.展开更多
The magnetocaloric effect of LaFe11.7Si1.3 compound was investigated under an external magnetic field up to 9 T.The magnetization changed drastically at the Curie temperature TC under different fields and TC increased...The magnetocaloric effect of LaFe11.7Si1.3 compound was investigated under an external magnetic field up to 9 T.The magnetization changed drastically at the Curie temperature TC under different fields and TC increased with the applied fields.The magnetic entropy change ｜？SM｜ vs temperature peak consisted of a spike and a plateau.The spike was a spurious result,while the plateau part resulted from the field-induced itinerant-electron metamagnetic（IEM） transition above TC,which went up with magnetic fields increasing.The width of the magnetic entropy change increased with magnetic fields at a rate of dL？S /dT^4 K/T.展开更多
The phase transition of Nd_(2)In and Pr_(2)In has been studied and found to be between the first-order and second-order nature.Hardly any hysteresis nor obvious cell volume changes are presented.Concurrently the field...The phase transition of Nd_(2)In and Pr_(2)In has been studied and found to be between the first-order and second-order nature.Hardly any hysteresis nor obvious cell volume changes are presented.Concurrently the field-triggered metamagnetism is demonstrated with lambda-like peak on specific heat curve.For the field change of 7 T,giant magnetic entropy changes of 13.2 J kg^(-1)K^(-1) and 19.5 J kg^(-1)K^(-1) and adiabatic temperature changes of 6.5 K and 7.4 K have been achieved in Nd_(2)In and Pr_(2) In alloys respectively,which is partially contributed by strong magnetoelastic coupling represented by high saturation magnetostriction of~450 ppm.Such unique feature is proposed to be originated from the delocalized 5d electrons,as evidenced by the negative magnetoresistance caused by the phase transition.展开更多
The structure and magnetic properties of MnCoSil_xPx （x = 0.054）.50） are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the s...The structure and magnetic properties of MnCoSil_xPx （x = 0.054）.50） are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the same time, the temperature of metamagnetic transition from a low-temperature non-collinear ferromagnetic state to a high-temperature ferromagnetic state decreases and a new magnetic transition from a higher-magnetization ferromagnetic state to a lower- magnetization ferromagnetic state is observed in each of these compounds for the first time. This is explained by the changes of crystal structure and distance between Mn and Si atoms with the increase of temperature according to the high- temperature XRD result. The metamagnetic transition is found to be a second-order magnetic transition accompanied by a low inversed magnetocaloric effect （1.0 J·kg-1 ·K- 1 at 5 T） with a large temperature span （190 K at 5 T） compared with the scenario of MnCoSi. The changes in the order of metamagnetic transition and structure make P-doped MoCoSi compounds good candidates for the study of magnetoelastic coupling and the modulation of magnetic phase transition.展开更多
Recent studies have shown that layered compound EuCd_(2)As_(2) could exhibit diverse topological states depending on the different magnetic structures,such as Weyl semimetal,Dirac semimetal and topological insulato r....Recent studies have shown that layered compound EuCd_(2)As_(2) could exhibit diverse topological states depending on the different magnetic structures,such as Weyl semimetal,Dirac semimetal and topological insulato r.In order to further study the interplay between magnetism and topology of EuCd_(2)As_(2),it is necessary to figure out its magnetic structure.Here,by magnetization(M) measurements and negative magnetostriction(λ) along the [001] direction measured by scanning tunneling microscopy on EuCd_(2)As_(2) single crystals,we observe field-induced metamagnetic phase transition from A-type antiferromagnetic(AFM) ground state to field-polarized state,with canted AFM(CAFM) state in between.Magnetization and magnetostriction are more sensitive to the in-plane field than the out-of-plane field,indicating the magnetic moments lying in the ab plane.The absence of abrupt jump on M-H and λ-H curves demonstrates that the phase transition is a second-order type.In CAFM state,M increases linearly with the field and λ is proportional to M~2.Tunneling conductance spectra show the field-induced evolution of the electronic density of states.Our results provide experimental evidence for understanding the magnetic structure of EuCd_(2)As_(2).展开更多
The ErCo2 compound is prepared by arc-melting and its entropy changes are calculated using Maxwell relation. Its entropy change reaches 38 J/（kg·K） and its refrigerant capacity achieves 291 J/kg at 0-5 T. The m...The ErCo2 compound is prepared by arc-melting and its entropy changes are calculated using Maxwell relation. Its entropy change reaches 38 J/（kg·K） and its refrigerant capacity achieves 291 J/kg at 0-5 T. The mean field approximation is used to calculate the magnetic entropy of ErCo2 compound. Results estimated by using the Maxwell relation deviate from mean field approximation calculations in ferrimagnetic state; however, the data obtained by the two ways are consistent in the vicinity of phase transition or at higher temperatures. This indicates that entropy changes are mainly derived from magnetic degree of freedom, and the lattice has almost no contribution to the entropy change in the vicinity of phase transition but its influence is obvious in the ferrimagnetic state below TC.展开更多
基金supported by the National Natural Science Foundation of China (90922006)the Natural Science Foundation of Jiangsu Province (BK2009009)
文摘Two manganese phosphonates Mn3（4-piH）2（H2O）3·H2O （1） and Mns（4-piH）2（4-piH2）2（phen）2（H2O）4 （2） （4-pill4 = 4-phosphonoisophthalic acid, phen = 1,10-phenanthroline） have been synthesized under hydrothermal conditions in the pres- ence of organic co-ligand. Both compounds exhibit layer structures but with different topologies. In compound 1, a complicated ＂ladder-like＂ chain of {Mn3O3}O2 which contains three- and six-member rings made up of triangular shaped {Mn3O3} tri- mers is found. The chains are linked by the PO3C groups to form an inorganic layer. The phenyl and protonated carboxylate groups are pendent between the layers with extensive hydrogen bonds. In compound 2, tetramers of {MnnO6 } are connected by the { MnO6 } octahedra through corner-sharing to form an infinite chain, which is further bridged by 4-pill3- ligands into a thick hybrid layer. Magnetic measurements reveal that antiferromagnetic interactions are dominant in both compounds. Metamag- netism is observed in compound 1 at low temperature, while no long range ordering is found in compound 2 down to 1.8 K.
基金supported by the National Natural Science Foundation of China (21201028, 21421005, 21322103, 91422302, 91122031)
文摘A cyanide-bridged Fei^III2Coll double zigzag chain, { [Fen1（bipy）（CN）4]2Con（btab）2}n [bipy=2,2＇-bipyridine, btab=4,4＇-（1,3-phen- ylene）-bis-4H-1,2,4-triazole] （1）, was obtained with tetracyanometalate precursors and Con ions. The chains were further linked by the ditopic btab ligands to a layer. Magnetic property studies demonstrate that 1 shows both metamagnetism with a critical field He=400 Oe and single-chain magnet behavior.
基金supported by the National Key R&D Program of China (2021YFB3501202,2021YFB3501204,2019YFA0704900,2020YFA0711500,2023YFA1406003,2022YFB3505201)the National Natural Science Foundation of China (52088101,U23A20550,92263202,22361132534)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB33030200)。
文摘This study presents an experimental investigation of the coupled caloric effect driven by dual-fields in metamagnetic alloy ErCo_(2) with strong magneto-structural coupling.Magnetic measurements were conducted under different pressures,revealing that the application of hydrostatic pressure stabilizes a small volume of paramagnetism(PM) phase,resulting in a shift of the phase transition temperature towards the low-temperature region.This shift is opposite to the temperature associated with the magnetic field-driven phase transition.As pressure increases,the metamagnetic transition in ErCo_(2) is suppressed,and the hysteresis disappears.However,the produced cross-coupling caloric effect compensates the decrease in entropy change caused by the disappearance of the metamagnetic transition.As a result,a reversible giant magnetocaloric effect of 46.2 J/(kg·K) without hysteresis is achieved at a pressure of 0.910 GPa.Moreover,we propose that the temperature span of ErCo_(2) can be significantly widened by optimizing the thermodynamic pathway of the magnetic and pressure fields,overcoming the defect of a narrow temperature range.
基金Project supported by the National Key Research and Development Program of China (Grant No. 2023YFA1406500)the National Natural Science Foundation of China (Grant Nos. 12474098, 12274388, 12174361, 12404043, and 12204004)the Natural Science Foundation of Anhui Province, China (Grant No. 2408085QA024)。
文摘The exploration and synthesis of new materials are important for materials science and condensed matter physics.Here, we report the crystal structure, magnetic properties, and electrical transport properties of the single crystals of Nd_(5)ScSb_(12), which is a quasi-one-dimensional new compound. Nd_(5)ScSb_(12) exhibits antiferromagnetic transition in both directions perpendicular and parallel to the long axis. Moreover, the magnetic field-dependent magnetization reveals two metamagnetic transitions. The electrical transport properties have been measured on the same sample but with different measurement lengths between the electrodes of the voltage. The resistivity exhibits the metallic behavior. At low temperatures, the Kondo effect and negative transverse magnetoresistance(MR)(B⊥I) have been observed. Interestingly, the measurement length has a significant impact on the Kondo effect and negative MR, providing an intuitive new approach to regulate the Kondo effect. As the measurement length increases, the Kondo effect and negative MR become more pronounced. This not only indicates that the interaction between magnetic impurities and conduction electrons dominates the electrical transport of Nd_(5)ScSb_(12) at low temperatures, but also confirms that the negative MR originates from the suppression of the Kondo effect.
基金supported by the National Key Research and Development Program of China (2021YFB3501204)the National Science Foundation for Excellent Young Scholars (52222107)+2 种基金the National Science Foundation for Distinguished Young Scholars (51925605)the National Natural Science Foundation of China (52171195)Projects of Ganjiang Innovation Academy,Chinese Academy of Sciences (E055B002)。
文摘The magnetic properties,magnetic phase transition and magnetocaloric effects(MCE) of Er_(3)Si_(2)C_(2) compound were investigated based on theoretical calculations and experimental analysis.Based on the first principles calculations,the antiferromagnetic(AFM) ground state type in Er_(3)Si_(2)C_(2) compound was predicted and its electronic structure was investigated.The experimental results show that Ei_(3)Si_(2)C_(2) compound is an AFM compound with the Neel temperature(T_(N) of 7 K and undergoes a field-induced firstorder magnetic phase transition from AFM to ferromagnetic(FM) under magnetic fields exceeding 0.6 T at 2 K.The magnetic transition process of Er_(3)Si_(2)C_(2) compound was investigated and discussed.The values of the maximum magnetic entropy change(-ΔS_(M)^(max)) and the refrigeration capacity(RC) are 17 J/(kg·K)and 193 J/kg under changing magnetic fields of 0-5 T,respectively.As a potential cryogenic magnetic refrigerant,the Er_(3)Si_(2)C_(2) compound also provides an interesting research medium to study the magnetic phase transition process.
文摘The dynamic magnetic behavior of the kinetic metamagnetic spin-5/2 Blume-Capel model is examined, within a mean-field approach, under a time-dependent oscillating magnetic field. To describe the kinetics of the system, Glauber- type stochastic dynamics has been utilized. The mean-field dynamic equations of the model are obtained from the Master equation. Firstly, these dynamic equations are solved to find the phases in the system. Then, the dynamic phase transition temperatures are obtained by investigating the thermal behavior of dynamic sublattice magnetizations. Moreover, from this investigation, the nature of the phase transitions （first- or second-order） is characterized. Finally, the dynamic phase diagrams are plotted in five different planes. It is found that the dynamic phase diagrams contain the paramagnetic （P）, antiferromagnetic （AF5/2, AF3/2, AF1/2） phases and five different mixed phases. The phase diagrams also display many dynamic critical points, such as tricritical point, triple point, quadruple point, double critical end point and separating point.
基金Project supported by the National Natural Science Foundation of China （Grant No 50571112）, the National Basic Reseaxch Program of China （Grant No 2006CB601101） and the Program of Chinese Academy of Sciences （Grant No KJCX2-YW-W02）.
文摘Magnetic properties and magnetic entropy changes in LaFe11.5Si1.5 have been investigated by partially substituting Pr by La. It is found that La1-xPrxFe11.5Si1.5 compounds remain cubic NaZn13-type structures even when the Pr content is increased to 0.5, i.e. x = 0.5. Substitution of Pr for La leads to a reduction in both the crystal constant and the Curie temperature. A stepwise magnetic behaviour in the isothermal magnetization curves is observed, indicating that the characteristic of the itinerant electron metamagnetic （IEM） transition above Tc becomes more prominent with the Pr content increasing. As a result, the magnetic entropy change is remarkably enhanced from 23.0 to 29.4 J/kg·K as the field changes from 0 to 5T, with the value of x increasing from 0 to 0.5. It is more attractive that the magnetic entropy changes for all samples are shaped into high plateaus in a wide range of temperature, which is highly favourable for Ericsson-type magnetic refrigeration.
基金the National Natural Science Foundation of China(Nos.51731005,51822102 and 51527801)the Fundamental Research Funds for the Central Universities(grant No.FRF-TP-18-008C1)Use of the Advanced Photon Source was supported by the U.S.Department of Energy,Office of Science,Office of Basic Energy Science,under Contract No.DE-AC02-06CH11357.
文摘An intrinsic two-way shape memory effect with a fully recoverable strain of 1.0%was achieved in an as-prepared Ni50Mn37.5Sn12.5 metamagnetic shape memory microwire fabricated by Taylor-Ulitovsky method.This two-way shape memory effect is mainly owing to the internal stress caused by the retained martensite in austenite matrix,as revealed by transmission electron microscopy observations and highenergy X-ray diffraction experiments.After superelastic training for 30 loading/unloading cycles at room temperature,the amount of retained martensite increased and the recoverable strain of two-way shape memory effect increased significantly to 2.2%.Furthermore,a giant recoverable strain of 11.2%was attained under a bias stress of 300 MPa in the trained microwire.These properties confer this microwire great potential for micro-actuation applications.
基金Project supported by the Key Project of National Natural Science Foundation of China(51176065)
文摘The FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites were prepared by hot pressing(HP). The microstructure,corrosion behavior and magnetocaloric effect(MCE) of FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites were investigated systematically. The results show that the corrosion resistance of FeNi coated LaFe_(11.6)Si_(1.4)Sn composites is better than that of LaFe_(11.6)Si_(1.4)/Sn composites in deionized water. The maximum magnetic entropy change((-△S_M)^(max)) and relative cooling power(RCP) of FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites are 13.30 J/(kg-K) and 146.25 J/kg, respectively, which are larger than that((-△S_M)^(max), 10.65 J/(kg·K) and RCP, 106.53 J/kg) of LaFe_(11.6)Si_(1.4)/Sn composites in a low magnetic field change of 2 T. FeNi coated LaFe_(11.6)Si_(1.4)/Sn composites possess a more negative slope. The improvement of magnetic properties is due to high permeability FeNi permalloy(1 J85) which improves the itinerant-electron metamagnetic(IEM) transition. So, the method of coating FeNi can provide a new idea for enhancing the corrosion resistance and magnetocaloric effect of La(Fe_xSi_(1-x))_(13)-based materials.
基金the National Natural Science Foundation of China(No.51771044)the Natural Science Foundation of Hebei Province(No.E2019501061)+2 种基金the Fundamental Research Funds for the Central Universities(No.N2023027)the Programme of Introducing Talents of Discipline Innovation to Universities 2.0(the 111 Project of China 2.0,No.BP0719037)the Liao Ning Revitalization Talents Program(No.XLYC1802023)。
文摘The Ni43.75Mn37.5In12.5Co6.25 alloy was obtained by using the spark plasma sintering(SPS)technique.The martensitic transformation,magnetic and mechanical properties of the SPS alloy were investigated.Key findings demonstrate that the martensitic transformation temperature of this alloy is about 10 K lower than that of the as-cast one.Both SPS and as-cast alloys show a 7 layered modulated martensite(7M)at room temperature.The compressive fracture strength and strain of the SPS alloy increase by 176.92%and 33.33%compared with the as-cast alloy,achieving 1440 MPa and 14%,respectively.The maximum magnetic entropy change Smis 17.1 J kg^(-1)K^(-1)for the SPS alloy at the magnetic field of 5 T.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.50701022 and 50831006)
文摘The magnetic phase transition and magnetocaloric effects in Fe-doped MnNiGe alloys are investigated. The substitution of Fe for Ni decreases the structural transition temperature remarkably, resulting in the magnetostructural transition occurring between antiferromagnetic and ferromagnetic states in MnNil_χFexGe alloy. Owing to the enhanced ferromagnetic coupling induced by the substitution of Fe, metamagnetic behaviour is also observed in TiNiSi-type phase of MnNil-xFezGe alloys at temperature below the structural transition temperature.
文摘Crystal structure, magnetic properties and magnetocaloric effects （MCE） of La1-xBixFe1 1.4Si1.6 （x=0.0 and 0.1） compounds were investigated by X-ray diffraction and magnetization measurements. The La1-xBixFe11.4Si1.6 compounds presented a cubic NaZnx3 type structure. First, the magnetization behavior and the magnetic transition were analyzed in terms of Landau theory. Then, Bi substitution for La in La1-xBixFe11.4Si1.6 compounds led to a decrease in magnetic entropy change （-△SM^max） but an increase in Curie temperature （Tc） significantly. The significant increase of Tc by Bi substitution from 202.5 to 256 K for x=0.0 and x=0.1 respectively was attributed to an increase in the Fe-Fe exchange interactions. Moreover, magnetocaloric effect was calculated in terms of isothermal magnetic entropy change. The maximum values of （-△SM^max ） of La1-xBixFe11.4Si1.6 for x=-0.0 and 0.1 compounds were found to be, respectively, 22.56 and 4.36 J/（kg.K） under an applied magnetic field change of 5 T. For the same applied magnetic field （μ0H=5 T）, the relative cooling power （RCP） values were found to vary between 487 and 296 J/kg.
基金Japanese Ministry of Education, Science, Sports and Culture!Grantin-Aid for Scientific Research (B)(2) 08455287
文摘A first-order itinerant electron metamagnetic (IEM) transition above the Curie temperature Tc for ferromagnetic La(Fe_xSi_1-x)13 compounds has been confirmed by applying magnetic field. The volume change just above T_C for x=0.88 is huge of about 1.5%, which is caused by a large magnetic moment induced by the IEM transition. These compounds have a possibility for practical applications as giant magnetostrictive materials. Pronounced Invar effects bring about a negative thermal expansion below TC, closely correlated with the negative mode-mode coupling among spin fluctuations.
基金financially supported by the Department of Science and Technology of Sichuan Province in China(No.2017JY0181)。
文摘The isothermal section of the Ho-Fe-In system at 773 K has been constructed by X-ray powder diffraction.One known structure ternary compound Er_(12)Fe_(2) In_(3)-type Ho_(12)Fe_(2) In_(3) has been confirmed.At the same time,solid solutions are not detected in Ho-Fe-In system at 773 K.The magnetic transition and magnetocaloric effect of Ho_(12)Fe_(2.08)In_(2.92) alloy with Er_(12)Fe_(2) In_(3)-type structure were investigated by magnetic susceptibility and isothermal magnetization measurements.One normal antiferromagnetic-paramagnetic transition and another abnormal one are discovered at 18 and 76 K in ground state,respectively.Owing to a first-order field-induced metamagnetic transition(antiferromagnetic-ferromagnetic) at/below the Neel temperature of 18 K),the negative entropy changes are observed at corresponding temperature.There is only a second-order ferromagnetic-paramagnetic transition near Curie temperature(TC),the maximum entropy change(Δ_(Smax)) values are-6.14 J·kg^(-1)·K^(-1) at 3 K and 7.88 J·kg^(-1)·K^(-1) at 28 K in a field range of 0-7 T.The reversible relative cooling power corresponding to negative entropy change can reach about 600 J·kg^(-1) in an wide operating temperature region Δ_(Tcycl)=74 K from 16 to90 K,which suggests that Ho_(12)Fe_(2.08)In_(2.92) could be a potential material for magnetic refrigeration in the corresponding temperature range.
基金Project supported by the Spanish MICINN and FEDER under Research Project No. MAT200763497SOPRANO Project Under Marie Curie Actions (FP7)
文摘The new scheelite form of SmCrO4 oxide was obtained by heating the zircon-type SmCrO4 oxide at 4 GPa and 803 K. X-ray diffraction revealed that this scheelite SmCrO4 phase crystallized with tetragonal symmetry, S.G. I41/a and lattice parameters: a=0.50776(3) nm and c=1.15606(2) nm. This structural phase transition from zircon to scheelite involved a decreasing of around 10% in the unit cell volume. Although the Cr-O and Sm-O distances did not change very much in both zircon and scheelite polymorphs, the changes occurred in the bond angles were remarkable that appear to support the proposed reconstructive model to explain this structural zircon-scheelite phase transition. Magnetic susceptibility and magnetization measurements revealed that the scheelite SmCrO4 oxide behaved an antiferromagnetic material, where the Sm3+ and Cr5+ were simultaneously ordered. The estimated Néel temperature, TN, was 16 K and the critical field at 12 K associated with the metamagnetic transition was 3.2 T.
基金supported by the National Natural Science Foundation of China(10304004)
文摘The magnetocaloric effect of LaFe11.7Si1.3 compound was investigated under an external magnetic field up to 9 T.The magnetization changed drastically at the Curie temperature TC under different fields and TC increased with the applied fields.The magnetic entropy change ｜？SM｜ vs temperature peak consisted of a spike and a plateau.The spike was a spurious result,while the plateau part resulted from the field-induced itinerant-electron metamagnetic（IEM） transition above TC,which went up with magnetic fields increasing.The width of the magnetic entropy change increased with magnetic fields at a rate of dL？S /dT^4 K/T.
基金supported by the National Natural Science Foundation of China (No. 51971056)the Fundamental Research Funds for the Central Universities (Nos. N2009001, N2009002, N2002005 and N2109005)+4 种基金the Joint Funding between Shenyang National Laboratory for Materials Science and State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals (No. 18LHPY014)the Open Fundings of the State Key Laboratory of Solidification Processing in NWPU (No. SKLSP201803)the State Key Laboratory for Mechanical Behavior of Materials (No. 20202206)the State Key Laboratory of Advanced Metals and Materials (No. 2019-ZD07)the Liaoning Revitalization Talent Program (No. XLYC1907175)。
文摘The phase transition of Nd_(2)In and Pr_(2)In has been studied and found to be between the first-order and second-order nature.Hardly any hysteresis nor obvious cell volume changes are presented.Concurrently the field-triggered metamagnetism is demonstrated with lambda-like peak on specific heat curve.For the field change of 7 T,giant magnetic entropy changes of 13.2 J kg^(-1)K^(-1) and 19.5 J kg^(-1)K^(-1) and adiabatic temperature changes of 6.5 K and 7.4 K have been achieved in Nd_(2)In and Pr_(2) In alloys respectively,which is partially contributed by strong magnetoelastic coupling represented by high saturation magnetostriction of~450 ppm.Such unique feature is proposed to be originated from the delocalized 5d electrons,as evidenced by the negative magnetoresistance caused by the phase transition.
基金Project supported by the National Natural Science Foundation of China(Grant No.11275013)the Fund from the National Physics Laboratory,China Academy of Engineering Physics(Grant No.2013DB01)the National Key Basic Research Program of China(Grant No.2010CB833104)
文摘The structure and magnetic properties of MnCoSil_xPx （x = 0.054）.50） are systematically investigated. With P content increasing, the lattice parameter a increases monotonically while both b and c decrease. At the same time, the temperature of metamagnetic transition from a low-temperature non-collinear ferromagnetic state to a high-temperature ferromagnetic state decreases and a new magnetic transition from a higher-magnetization ferromagnetic state to a lower- magnetization ferromagnetic state is observed in each of these compounds for the first time. This is explained by the changes of crystal structure and distance between Mn and Si atoms with the increase of temperature according to the high- temperature XRD result. The metamagnetic transition is found to be a second-order magnetic transition accompanied by a low inversed magnetocaloric effect （1.0 J·kg-1 ·K- 1 at 5 T） with a large temperature span （190 K at 5 T） compared with the scenario of MnCoSi. The changes in the order of metamagnetic transition and structure make P-doped MoCoSi compounds good candidates for the study of magnetoelastic coupling and the modulation of magnetic phase transition.
基金Project supported by the National Natural Science Foundation of China(11227903,12004416,U2032204)the Beijing Municipal Science and Technology Commission(Z181100004218007,Z191100007219011)+3 种基金the National Basic Research Program of China(2015CB921304)the National Key Research and Development Program of China(2017YFA0302903,2016YFJC010282,2016YFA0300602,2016YFA0300604)the Strategic Priority Research Program of Chinese Academy of Sciences(XDB07000000,XDB28000000,XDB33000000)。
文摘Recent studies have shown that layered compound EuCd_(2)As_(2) could exhibit diverse topological states depending on the different magnetic structures,such as Weyl semimetal,Dirac semimetal and topological insulato r.In order to further study the interplay between magnetism and topology of EuCd_(2)As_(2),it is necessary to figure out its magnetic structure.Here,by magnetization(M) measurements and negative magnetostriction(λ) along the [001] direction measured by scanning tunneling microscopy on EuCd_(2)As_(2) single crystals,we observe field-induced metamagnetic phase transition from A-type antiferromagnetic(AFM) ground state to field-polarized state,with canted AFM(CAFM) state in between.Magnetization and magnetostriction are more sensitive to the in-plane field than the out-of-plane field,indicating the magnetic moments lying in the ab plane.The absence of abrupt jump on M-H and λ-H curves demonstrates that the phase transition is a second-order type.In CAFM state,M increases linearly with the field and λ is proportional to M~2.Tunneling conductance spectra show the field-induced evolution of the electronic density of states.Our results provide experimental evidence for understanding the magnetic structure of EuCd_(2)As_(2).
基金Project supported by the National Natural Science Foundation of China （Grant No 50571112） and the National Basic Research Program of China （Grant No 2006CB601101）.
文摘The ErCo2 compound is prepared by arc-melting and its entropy changes are calculated using Maxwell relation. Its entropy change reaches 38 J/（kg·K） and its refrigerant capacity achieves 291 J/kg at 0-5 T. The mean field approximation is used to calculate the magnetic entropy of ErCo2 compound. Results estimated by using the Maxwell relation deviate from mean field approximation calculations in ferrimagnetic state; however, the data obtained by the two ways are consistent in the vicinity of phase transition or at higher temperatures. This indicates that entropy changes are mainly derived from magnetic degree of freedom, and the lattice has almost no contribution to the entropy change in the vicinity of phase transition but its influence is obvious in the ferrimagnetic state below TC.
