The temperature-driven spin reorientation transition of magnetron sputtered Ni/Si （111） systems has been studied. The relationship between ac initial susceptibility and temperature of nickel films with different thi...The temperature-driven spin reorientation transition of magnetron sputtered Ni/Si （111） systems has been studied. The relationship between ac initial susceptibility and temperature of nickel films with different thicknesses shows that the magnetization orientation changes from in-plane to out-of-plane with the increase of temperature. The temperature dependence of mugnetoelastic, magneto-crystalline, and magnetostatic anisotropies determines the direction of the reorientation transition. The temperature-driven spin reorientation transition is supported by Hall coefficient measurements which show that its temperature dependence is similar to that of susceptibility.展开更多
DyTiFe_(11) compound is a ferromagnetic substance.It has tetragonal body-centered ThMn_(12)-type crystallographic structure.At room temperature,the easy magnetization direction is the c-axis.A spin reorientation begin...DyTiFe_(11) compound is a ferromagnetic substance.It has tetragonal body-centered ThMn_(12)-type crystallographic structure.At room temperature,the easy magnetization direction is the c-axis.A spin reorientation begins to appear at about 175K.The contribution of Fe sublattice to magnetocrystalline anisotropy was determined by experiments and that of Dy sublattice was obtained by using single ion model calculation.Results show that the spin reorientation arises from the competition of anisotropy between Fe and Dy sublattices.展开更多
Rare-earth orthoferrites(RFeO_(3)),which are canted antiferromagnets exhibiting weak ferromagnetism,are potential materials for spintronic devices.The temperature of spin reorientation transition(SRT)in Tm_(1-x)Pr_(x)...Rare-earth orthoferrites(RFeO_(3)),which are canted antiferromagnets exhibiting weak ferromagnetism,are potential materials for spintronic devices.The temperature of spin reorientation transition(SRT)in Tm_(1-x)Pr_(x)FeO_(3)(x=0,0.15,0.25,0.5)single crystals shifts to a lower region with the increase of x,attributing to the exchange energy of Pr^(3+)-Fe^(3+)being less than that of Tm^(3+)-Fe^(3+).Both type-I of spin switching(SSW-I)and the type-Ⅱ of spin switching(SSW-Ⅱ)are observed along the a-axis when x=0.15 and 0.2.The changes of magnetic interaction are analyzed through structural distortion and transforming Curi–Weiss fitting.A rare SSW-Ⅱ phenomenon is observed along the c-axis during both the cooling and warming processes when x=0.15,0.25,0.5.In addition,a weak ferromagnetic moment(WFM)component is observed despite the antiferromagnetic behavior at high temperature in Tm_(0.5)Pr_(0.5)FeO_(3) single crystal.The WFM decreases gradually with the increase in temperature,indicating the occurrence of SRT.And the field-induced spin switching(SSW)is observed along the a-axis at 70 K when x=0.5.The magnetic properties of Pr^(3+)doped TmFeO_(3) single crystals are obviously different from TmFeO_(3) and PrFeO_(3) single crystals,indicating the complex magnetic interaction among Pr^(3+),Tm^(3+)and Fe^(3+).The complex and abundant magnetic phenomena in Tm_(1-x)Pr_(x)FeO_(3) single crystals offer significant potential for studying altermagnet and magneto-optical coupling,and are expected to become a new generation of spintronic devices.展开更多
The effects of Al substitution for Fe on the structure,magnetics,magnetostriction,anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys(x=0.05,0.1,0.15,0.2,0.25,0.3)at room temperature ...The effects of Al substitution for Fe on the structure,magnetics,magnetostriction,anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys(x=0.05,0.1,0.15,0.2,0.25,0.3)at room temperature have been investigated.The alloys of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 substantially retain MgCu2-type C-15 cubic Laves phase structure when x【0.2.The mixed phases appear with x=0.2,and cubic Laves phase decreases with increasing x.The magnetostriction of the Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys decreases drastically with increasing x and the giant magnetostrictive effect disappears for x】0.15.Fortunately,a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy.The spin reorientation temperature decreases with increasing x.The analysis of the Mssbauer spectra indicates that the easy magnetization direction in the{110}plane deviates slightly from the main axis of symmetry with the increase of Al concentration x,namely,spin reorientation,resulting in the change of macroscopical magnetic properties and magnetostriction.The hyperfine field decreases,but the isomer shifts increases with Al concentration increasing and the quadruple splitting QS shows a weak concentration dependence.展开更多
Nd12.3Fe81.7-xZrxB6.0(x=0,1.5)and(NdDyTb)12.3(FeZrNbCu)81.7-yCoyB6.0(y=0,12)ribbons were prepared by melt spinning at 22 m/s and subsequent annealing.The influences of Zr,Dy/Tb and Co substitutions on magnetic propert...Nd12.3Fe81.7-xZrxB6.0(x=0,1.5)and(NdDyTb)12.3(FeZrNbCu)81.7-yCoyB6.0(y=0,12)ribbons were prepared by melt spinning at 22 m/s and subsequent annealing.The influences of Zr,Dy/Tb and Co substitutions on magnetic properties and spin reorientation transitions of nanophase Nd2Fe14B have been systematically investigated.Compared with Zr-free sample,the remanence,intrinsic coercivity and maximum energy product for Nd12.3Fe80.2Zr1.5B6.0 ribbon increase by 10.8%,17.8%and 60.2%,respectively.The significant improvement of magnetic properties originates from the finer grains of the sample by introducing Zr,which leads to the stronger exchange coupling between neighboring grains.The intrinsic coercivity for(DyTb)-substituted ribbon is significantly increased although the remanence is reduced,which could be compensated by the substitution of Co for Fe.The spin reorientation temperature Tsr of nanocrystalline Nd2Fe14B alloys was determined by measuring the ac magnetic susceptibility.It was found to be lower than that of bulk Nd2Fe14B.The substitutions of Zr,Dy/Tb and Co result in reduction of Tsr.The smaller the grain size,the lower the Tsr will be.Influence of spin reorientation on magnetization characteristics of nanophase Nd2Fe14B was discussed.展开更多
Spin reorientation transition (SRT) has attracted substantial attention due to its important role in the ultrafast control of spins. However, the transition temperature is usually too low for its practical application...Spin reorientation transition (SRT) has attracted substantial attention due to its important role in the ultrafast control of spins. However, the transition temperature is usually too low for its practical applications. Here, we demonstrate the ability to modulate the SRT temperature in PrFe_(1−x)Mn_(x)O_(3) single crystals from 196 K to 317 K across the room temperature by varying the Mn concentration. Interestingly, the Γ_(4) to Γ_(1) spin reorientation of the Mn-doped PrFeO_(3) is distinct from the Γ_(4) to Γ_(2) spin reorientation transition as in the parent material. Because of the coupling between rare-earth ions and transition-metal ions in determining the SRT temperature, the demonstrated control scheme of spin reorientation transition temperature by Mn-doping is expected to be used in temperature control magnetic switching devices and applicable to many other rare-earth orthoferrites.展开更多
The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties,anisotropy,spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.20,0.25,0.30,0.35)alloys ...The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties,anisotropy,spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.20,0.25,0.30,0.35)alloys at room temperature have been investigated.It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys.The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2.However,the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H.The saturation magnetization and Curie temperature decrease monotonously,but the spontaneous magnetostriction increases linearly with increasing x,whereas the spin reorientation temperature increases first,then decreases rapidly and reaches the maximum at x=0.1.The analysis of Mssbauer spectra indicated that the easy magnetization direction in the{110}plane deviates slightly from the main axis of symmetry with the Pr concentration x,namely spin reorientation.Compared with Al substitution for Fe,the effect of Pr substitution for Dy on spin reorientation is relatively small.The hyperfine field increases with Pr concentration increasing,and the isomer shifts and the quadrupole splitting(QS)show weak concentration dependence.展开更多
We review recent studies by different experimental means of ultrathin films,exhibiting thickness-driven spin reorientation transitions(SRTs).The stage is set by determining,via phenomenological thermodynamic descripti...We review recent studies by different experimental means of ultrathin films,exhibiting thickness-driven spin reorientation transitions(SRTs).The stage is set by determining,via phenomenological thermodynamic description,of the relevant phase diagrams for the possible types of SRT with and without applied magnetic field.Suitable representation may be chosen such that best use is made of the linear character(under thickness variation) of the system's path in anisotropy space.The latter involves higher-order bulk and surface anisotropies in a substantial way.We examine sensitive experimental techniques for the detection and quantification of SRTs,such as hysteresis measurements with magneto-optical Kerr effect(MOKE),micromagnetic studies utilizing scanning electron microscopy with polarization analysis(SEMPA),photoemission electron microscopy(PEEM) and spin-polarized low-energy electron microscopy(SPLEEM) as well as ac magnetic susceptibility measurements via MOKE.Key issues are conclusively discussed including the identification of reliable experimental fingerprints about whether a given SRT proceeds via a phase of coexistence or via a cone(canted) phase.We demonstrate how the application of the general theoretical ideas to carefully designed measurements leads to the determination of the most important material parameters in any ultrathin-film SRT,namely,the surface(interface) magnetic anisotropy constants.The review concludes by our personal outline for future promising work on SRTs.展开更多
A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit c...A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment （μeff） and the Curie constant （C） were calculated from the reciprocal of the molar magnetic susceptibility （Z-1） versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature （TN） and spin reorientation （TsR） transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.展开更多
The magnetic properties of commercial polycrystalline Nd2Fe14B （N50M,N45H,N40SH,N35EH） and Sm2Co17（XG30/20,XG26/25,XG22/20） magnets at cryogenic temperatures were tested by using a comprehensive physical propertie...The magnetic properties of commercial polycrystalline Nd2Fe14B （N50M,N45H,N40SH,N35EH） and Sm2Co17（XG30/20,XG26/25,XG22/20） magnets at cryogenic temperatures were tested by using a comprehensive physical properties measurement system （PPMS）. The results show that the spin tilt temperature Tst of Nd2Fe14B magnets is closely related to intrinsic coercivity Hci , N50M and N45H with smaller Hci show a residual magnetization jump at 235K and 225K, respectively. For Sm2Co17 magnets, in 50-300 K, with temperature decreasing, residual magnetization Mrc shows a nearly linear increase, while in 10-50 K, Mrc has little change. The research results provide a reference for cryogenic undulators and other high-precision cryogenic devices.展开更多
Multiferroic properties in a polycrystalline terbium orthoferrite are investigated. Different thermomagnetic behaviors are observed in different magnetic fields, which is attributed to the suppression of the low tempe...Multiferroic properties in a polycrystalline terbium orthoferrite are investigated. Different thermomagnetic behaviors are observed in different magnetic fields, which is attributed to the suppression of the low temperature magnetic phase by an external magnetic field. Further studies reveal that the ferroelectricity originates from the spin configuration below 3.5 K. In addition, the magnetic field control of electric polarization and dielectric constant is observed, which suggests a magnetoelectric effect in TbFeO3. The origin of ferroelectricity in this rare-earth orthoferrite is discussed.展开更多
NdMn_(6-x)CoxSn_6(x=0,0.2,0.4,0.6,0.8,1,1.5) were found to crystallize in the YCoeGe6 type structure.The magnetic ordering temperature(Curie temperature) and the saturation magnetization at room temperature decreases ...NdMn_(6-x)CoxSn_6(x=0,0.2,0.4,0.6,0.8,1,1.5) were found to crystallize in the YCoeGe6 type structure.The magnetic ordering temperature(Curie temperature) and the saturation magnetization at room temperature decreases with increasing Co content in NdMn_(6-x)Co_xSn_6 compounds.The spin reorientation process appears in all compounds.The spin orientation temperature increases with increasing Co content for NdMn_(3-x)Co_xSn_6.展开更多
The magnetization reversal of Fe/Cu（100） ultrathin films grown at room temperature is investigated by using an in situ magneto-optical Kerr effect polarimeter with a magnet that can rotate in a plane of incidence. T...The magnetization reversal of Fe/Cu（100） ultrathin films grown at room temperature is investigated by using an in situ magneto-optical Kerr effect polarimeter with a magnet that can rotate in a plane of incidence. There occur spin reorientation transitions from out-of-plane to in-plane magnetizations in 8 and 12 monolayers （ML） thick iron films. The coercive fields are observed to be proportional to the reciprocal of the cosine with respect to the easy axis, suggesting that the domain-wall displacement plays a main role in the magnetization reversal process.展开更多
Rare-earth orthoferrite REFeO_(3)(where RE is a rare-earth ion)is gaining interest.We created a high-entropy orthoferrite(Tm_(0.2)Nd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))FeO_(3)(HEOR)by doping five RE ions in equimolar ratios...Rare-earth orthoferrite REFeO_(3)(where RE is a rare-earth ion)is gaining interest.We created a high-entropy orthoferrite(Tm_(0.2)Nd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))FeO_(3)(HEOR)by doping five RE ions in equimolar ratios and grew the single crystal by optical floating zone method.It strongly tends to form a single-phase structure stabilized by high configurational entropy.In the low-temperature region(11.6‒14.4 K),the spin reorientation transition(SRT)ofΓ_(2)(F_(x),C_(y),G_(z))‒Γ_(24)‒Γ_(4)(G_(x),A_(y),F_(z))occurs.The weak ferromagnetic(FM)moment,which comes from the Fe sublattices distortion,rotates from the a-to c-axis.The two-step dynamic processes(Γ_(2)‒Γ_(24)‒Γ_(4))are identified by AC susceptibility measurements.SRT in HEOR can be tuned in the range of 50‒60000 Oe,which is an order of magnitude larger than that of orthoferrites in the peer system,making it a candidate for high-field spin sensing.Typical spin-switching(SSW)and continuous spin-switching(CSSW)effects occur under low magnetic fields due to the strong interactions between RE‒Fe sublattices.The CSSW effect is tunable between 20‒50 Oe,and hence,HEOR potentially can be applied to spin modulation devices.Furthermore,because of the strong anisotropy of magnetic entropy change()and refrigeration capacity(RC)based on its high configurational entropy,HEOR is expected to provide a novel approach for refrigeration by altering the orientations of the crystallographic axes(anisotropic configurational entropy).展开更多
The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties,anisotropy,spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.20,0.25,0.30,0.35)alloys ...The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties,anisotropy,spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.20,0.25,0.30,0.35)alloys at room temperature have been investigated.It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys.The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2.However,the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H.The saturation magnetization and Curie temperature decrease monotonously,but the spontaneous magnetostriction increases linearly with increasing x,whereas the spin reorientation temperature increases first,then decreases rapidly and reaches the maximum at x=0.1.The analysis of Mssbauer spectra indicated that the easy magnetization direction in the{110}plane deviates slightly from the main axis of symmetry with the Pr concentration x,namely spin reorientation.Compared with Al substitution for Fe,the effect of Pr substitution for Dy on spin reorientation is relatively small.The hyperfine field increases with Pr concentration increasing,and the isomer shifts and the quadrupole splitting(QS)show weak concentration dependence.展开更多
基金supported by the National Natural Science Foundation of China (Grant No 10334080)
文摘The temperature-driven spin reorientation transition of magnetron sputtered Ni/Si （111） systems has been studied. The relationship between ac initial susceptibility and temperature of nickel films with different thicknesses shows that the magnetization orientation changes from in-plane to out-of-plane with the increase of temperature. The temperature dependence of mugnetoelastic, magneto-crystalline, and magnetostatic anisotropies determines the direction of the reorientation transition. The temperature-driven spin reorientation transition is supported by Hall coefficient measurements which show that its temperature dependence is similar to that of susceptibility.
文摘DyTiFe_(11) compound is a ferromagnetic substance.It has tetragonal body-centered ThMn_(12)-type crystallographic structure.At room temperature,the easy magnetization direction is the c-axis.A spin reorientation begins to appear at about 175K.The contribution of Fe sublattice to magnetocrystalline anisotropy was determined by experiments and that of Dy sublattice was obtained by using single ion model calculation.Results show that the spin reorientation arises from the competition of anisotropy between Fe and Dy sublattices.
基金supported by the National Natural Science Foundation of China(NSFC,No.12374116)a fellowship from the China Postdoctoral Science Foundation(Certificate No.2024M751931).
文摘Rare-earth orthoferrites(RFeO_(3)),which are canted antiferromagnets exhibiting weak ferromagnetism,are potential materials for spintronic devices.The temperature of spin reorientation transition(SRT)in Tm_(1-x)Pr_(x)FeO_(3)(x=0,0.15,0.25,0.5)single crystals shifts to a lower region with the increase of x,attributing to the exchange energy of Pr^(3+)-Fe^(3+)being less than that of Tm^(3+)-Fe^(3+).Both type-I of spin switching(SSW-I)and the type-Ⅱ of spin switching(SSW-Ⅱ)are observed along the a-axis when x=0.15 and 0.2.The changes of magnetic interaction are analyzed through structural distortion and transforming Curi–Weiss fitting.A rare SSW-Ⅱ phenomenon is observed along the c-axis during both the cooling and warming processes when x=0.15,0.25,0.5.In addition,a weak ferromagnetic moment(WFM)component is observed despite the antiferromagnetic behavior at high temperature in Tm_(0.5)Pr_(0.5)FeO_(3) single crystal.The WFM decreases gradually with the increase in temperature,indicating the occurrence of SRT.And the field-induced spin switching(SSW)is observed along the a-axis at 70 K when x=0.5.The magnetic properties of Pr^(3+)doped TmFeO_(3) single crystals are obviously different from TmFeO_(3) and PrFeO_(3) single crystals,indicating the complex magnetic interaction among Pr^(3+),Tm^(3+)and Fe^(3+).The complex and abundant magnetic phenomena in Tm_(1-x)Pr_(x)FeO_(3) single crystals offer significant potential for studying altermagnet and magneto-optical coupling,and are expected to become a new generation of spintronic devices.
基金supported by the National Natural Science Foundation of China(Grant No.10574059)the Natural Science Foundation of Gansu Province(Grant No.0710RJZA074)+2 种基金the Scientific Research Project of Bureau of Education of Gansu Province(Grant No.0711B-04)the Key Project of the Science and Technology Research of Ministry of Education(Grant No.209127)the"Qing Lan"Talent Engineering Funds of Lanzhou Jiaotong University
文摘The effects of Al substitution for Fe on the structure,magnetics,magnetostriction,anisotropy and spin reorientation of a series of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys(x=0.05,0.1,0.15,0.2,0.25,0.3)at room temperature have been investigated.The alloys of Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 substantially retain MgCu2-type C-15 cubic Laves phase structure when x【0.2.The mixed phases appear with x=0.2,and cubic Laves phase decreases with increasing x.The magnetostriction of the Tb0.3Dy0.6Pr0.1(Fe1-xAlx)1.95 alloys decreases drastically with increasing x and the giant magnetostrictive effect disappears for x】0.15.Fortunately,a small amount of Al substitution is beneficial to a decrease in the magnetocrystalline anisotropy.The spin reorientation temperature decreases with increasing x.The analysis of the Mssbauer spectra indicates that the easy magnetization direction in the{110}plane deviates slightly from the main axis of symmetry with the increase of Al concentration x,namely,spin reorientation,resulting in the change of macroscopical magnetic properties and magnetostriction.The hyperfine field decreases,but the isomer shifts increases with Al concentration increasing and the quadruple splitting QS shows a weak concentration dependence.
文摘Nd12.3Fe81.7-xZrxB6.0(x=0,1.5)and(NdDyTb)12.3(FeZrNbCu)81.7-yCoyB6.0(y=0,12)ribbons were prepared by melt spinning at 22 m/s and subsequent annealing.The influences of Zr,Dy/Tb and Co substitutions on magnetic properties and spin reorientation transitions of nanophase Nd2Fe14B have been systematically investigated.Compared with Zr-free sample,the remanence,intrinsic coercivity and maximum energy product for Nd12.3Fe80.2Zr1.5B6.0 ribbon increase by 10.8%,17.8%and 60.2%,respectively.The significant improvement of magnetic properties originates from the finer grains of the sample by introducing Zr,which leads to the stronger exchange coupling between neighboring grains.The intrinsic coercivity for(DyTb)-substituted ribbon is significantly increased although the remanence is reduced,which could be compensated by the substitution of Co for Fe.The spin reorientation temperature Tsr of nanocrystalline Nd2Fe14B alloys was determined by measuring the ac magnetic susceptibility.It was found to be lower than that of bulk Nd2Fe14B.The substitutions of Zr,Dy/Tb and Co result in reduction of Tsr.The smaller the grain size,the lower the Tsr will be.Influence of spin reorientation on magnetization characteristics of nanophase Nd2Fe14B was discussed.
基金This work was supported by the Ministry of Science and Technology of the People’s Republic of China(No.2018YFB0704402)the National Natural Science Foundation of China(NSFC,Nos.12074242,11774217,and 12074241)the Science and Technology Commission of Shanghai Municipality(No.21JC1402600).
文摘Spin reorientation transition (SRT) has attracted substantial attention due to its important role in the ultrafast control of spins. However, the transition temperature is usually too low for its practical applications. Here, we demonstrate the ability to modulate the SRT temperature in PrFe_(1−x)Mn_(x)O_(3) single crystals from 196 K to 317 K across the room temperature by varying the Mn concentration. Interestingly, the Γ_(4) to Γ_(1) spin reorientation of the Mn-doped PrFeO_(3) is distinct from the Γ_(4) to Γ_(2) spin reorientation transition as in the parent material. Because of the coupling between rare-earth ions and transition-metal ions in determining the SRT temperature, the demonstrated control scheme of spin reorientation transition temperature by Mn-doping is expected to be used in temperature control magnetic switching devices and applicable to many other rare-earth orthoferrites.
基金Supported by the National Natural Science Foundation of China(Grant No.10574059)the Natural Science Foundation of Gansu Province(Grant No.0710RJZA074)+1 种基金the Second Scientific Research Project of Bureau of Gansu Education‘Qing Lan’Talent Engineering Funds of Lanzhou Jiaotong University
文摘The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties,anisotropy,spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.20,0.25,0.30,0.35)alloys at room temperature have been investigated.It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys.The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2.However,the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H.The saturation magnetization and Curie temperature decrease monotonously,but the spontaneous magnetostriction increases linearly with increasing x,whereas the spin reorientation temperature increases first,then decreases rapidly and reaches the maximum at x=0.1.The analysis of Mssbauer spectra indicated that the easy magnetization direction in the{110}plane deviates slightly from the main axis of symmetry with the Pr concentration x,namely spin reorientation.Compared with Al substitution for Fe,the effect of Pr substitution for Dy on spin reorientation is relatively small.The hyperfine field increases with Pr concentration increasing,and the isomer shifts and the quadrupole splitting(QS)show weak concentration dependence.
基金supported by the State Key Programme for Basic Research of China (Grant No. 2010CB923401)National Natural Science Foundation of China (Grant Nos. 10834001,10974087 and 11023002)Natural Science Foundation of Jiangsu (Grant No. BK2012300)
文摘We review recent studies by different experimental means of ultrathin films,exhibiting thickness-driven spin reorientation transitions(SRTs).The stage is set by determining,via phenomenological thermodynamic description,of the relevant phase diagrams for the possible types of SRT with and without applied magnetic field.Suitable representation may be chosen such that best use is made of the linear character(under thickness variation) of the system's path in anisotropy space.The latter involves higher-order bulk and surface anisotropies in a substantial way.We examine sensitive experimental techniques for the detection and quantification of SRTs,such as hysteresis measurements with magneto-optical Kerr effect(MOKE),micromagnetic studies utilizing scanning electron microscopy with polarization analysis(SEMPA),photoemission electron microscopy(PEEM) and spin-polarized low-energy electron microscopy(SPLEEM) as well as ac magnetic susceptibility measurements via MOKE.Key issues are conclusively discussed including the identification of reliable experimental fingerprints about whether a given SRT proceeds via a phase of coexistence or via a cone(canted) phase.We demonstrate how the application of the general theoretical ideas to carefully designed measurements leads to the determination of the most important material parameters in any ultrathin-film SRT,namely,the surface(interface) magnetic anisotropy constants.The review concludes by our personal outline for future promising work on SRTs.
文摘A1 doped SmFeO3 （SmFel_xmlxO3; 0.0〈x〈0.15; step 0.05） were prepared by double sintering ceramic technique. The obtained samples were crystallized in single phase structure except the sample with x=0.15. The unit cell volume was found to decrease with increasing AI substitution in orthoferrite. The effective magnetic moment （μeff） and the Curie constant （C） were calculated from the reciprocal of the molar magnetic susceptibility （Z-1） versus absolute temperature plot and found to attain maximum value for the parent sample. The magnetic behavior showed two different magnetic transitions, viz, N6el temperature （TN） and spin reorientation （TsR） transitions. The M-H hysteresis loop of the parent sample took butterfly-shape as a result of different contributions anisotropies. From the magnetic properties measurements, it was obviously found that B-site cation dilution resulted in a drastic decrease in the magnetization. Surprisingly large value of the coercive field was obtained for the undoped sample;Hc=6198.80e. Based on the mentioned results, one can recommend the use of such orthoferrite in magnetic recording media and as pining layer in spin valve for spin- tronic applications.
基金the Natural Science Foundation of Shanghai,China(Grant No.11ZR1445500)the National Natural Science Foundation of China(Grant No.11175238)
文摘The magnetic properties of commercial polycrystalline Nd2Fe14B （N50M,N45H,N40SH,N35EH） and Sm2Co17（XG30/20,XG26/25,XG22/20） magnets at cryogenic temperatures were tested by using a comprehensive physical properties measurement system （PPMS）. The results show that the spin tilt temperature Tst of Nd2Fe14B magnets is closely related to intrinsic coercivity Hci , N50M and N45H with smaller Hci show a residual magnetization jump at 235K and 225K, respectively. For Sm2Co17 magnets, in 50-300 K, with temperature decreasing, residual magnetization Mrc shows a nearly linear increase, while in 10-50 K, Mrc has little change. The research results provide a reference for cryogenic undulators and other high-precision cryogenic devices.
基金supported by the National Basic Research Program of China(Grant Nos.2012CB932304 and 2014AA032904)the National Natural ScienceFoundation of China(Grant Nos.11174130 and U1232210)
文摘Multiferroic properties in a polycrystalline terbium orthoferrite are investigated. Different thermomagnetic behaviors are observed in different magnetic fields, which is attributed to the suppression of the low temperature magnetic phase by an external magnetic field. Further studies reveal that the ferroelectricity originates from the spin configuration below 3.5 K. In addition, the magnetic field control of electric polarization and dielectric constant is observed, which suggests a magnetoelectric effect in TbFeO3. The origin of ferroelectricity in this rare-earth orthoferrite is discussed.
文摘NdMn_(6-x)CoxSn_6(x=0,0.2,0.4,0.6,0.8,1,1.5) were found to crystallize in the YCoeGe6 type structure.The magnetic ordering temperature(Curie temperature) and the saturation magnetization at room temperature decreases with increasing Co content in NdMn_(6-x)Co_xSn_6 compounds.The spin reorientation process appears in all compounds.The spin orientation temperature increases with increasing Co content for NdMn_(3-x)Co_xSn_6.
基金supported by the State Key Development Program for Basic Research of China (Grant No 2001CB610605)the National Natural Science Foundation of China (Grant No 10774179)
文摘The magnetization reversal of Fe/Cu（100） ultrathin films grown at room temperature is investigated by using an in situ magneto-optical Kerr effect polarimeter with a magnet that can rotate in a plane of incidence. There occur spin reorientation transitions from out-of-plane to in-plane magnetizations in 8 and 12 monolayers （ML） thick iron films. The coercive fields are observed to be proportional to the reciprocal of the cosine with respect to the easy axis, suggesting that the domain-wall displacement plays a main role in the magnetization reversal process.
基金supported by the research grant from the National Natural Science Foundation of China(NSFC)(Nos.12074242 and 12204298)the Science and Technology Commission of Shanghai Municipality(No.21JC1402600).
文摘Rare-earth orthoferrite REFeO_(3)(where RE is a rare-earth ion)is gaining interest.We created a high-entropy orthoferrite(Tm_(0.2)Nd_(0.2)Dy_(0.2)Y_(0.2)Yb_(0.2))FeO_(3)(HEOR)by doping five RE ions in equimolar ratios and grew the single crystal by optical floating zone method.It strongly tends to form a single-phase structure stabilized by high configurational entropy.In the low-temperature region(11.6‒14.4 K),the spin reorientation transition(SRT)ofΓ_(2)(F_(x),C_(y),G_(z))‒Γ_(24)‒Γ_(4)(G_(x),A_(y),F_(z))occurs.The weak ferromagnetic(FM)moment,which comes from the Fe sublattices distortion,rotates from the a-to c-axis.The two-step dynamic processes(Γ_(2)‒Γ_(24)‒Γ_(4))are identified by AC susceptibility measurements.SRT in HEOR can be tuned in the range of 50‒60000 Oe,which is an order of magnitude larger than that of orthoferrites in the peer system,making it a candidate for high-field spin sensing.Typical spin-switching(SSW)and continuous spin-switching(CSSW)effects occur under low magnetic fields due to the strong interactions between RE‒Fe sublattices.The CSSW effect is tunable between 20‒50 Oe,and hence,HEOR potentially can be applied to spin modulation devices.Furthermore,because of the strong anisotropy of magnetic entropy change()and refrigeration capacity(RC)based on its high configurational entropy,HEOR is expected to provide a novel approach for refrigeration by altering the orientations of the crystallographic axes(anisotropic configurational entropy).
基金supported by National Natural Science Foundation of China(Grant Nos.60373093,60533060,10726068,10801024)the Innovation Foundation of Key Laboratory of High Temperature Gasdynamics of Chinese Academy of Sciences,China
文摘The effect of Pr substitution for Dy on the magnetic and magnetostrictive properties,anisotropy,spin reorientation and Mssbauer effect of a series of Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95(x=0,0.1,0.20,0.25,0.30,0.35)alloys at room temperature have been investigated.It was found that a small amount of Pr substitution is beneficial to a decrease in the magnetocrystalline anisotropy for the Tb0.3Dy0.7-xPrx(Fe0.9Al0.1)1.95 alloys.The magnetostriction decreases drastically with increasing x and the magnetostrictive effect disappears for x>0.2.However,the magnetostriction exhibits a slightly bigger value at x=0.1 than the free alloys and is saturated more easily with the magnetic field H.The saturation magnetization and Curie temperature decrease monotonously,but the spontaneous magnetostriction increases linearly with increasing x,whereas the spin reorientation temperature increases first,then decreases rapidly and reaches the maximum at x=0.1.The analysis of Mssbauer spectra indicated that the easy magnetization direction in the{110}plane deviates slightly from the main axis of symmetry with the Pr concentration x,namely spin reorientation.Compared with Al substitution for Fe,the effect of Pr substitution for Dy on spin reorientation is relatively small.The hyperfine field increases with Pr concentration increasing,and the isomer shifts and the quadrupole splitting(QS)show weak concentration dependence.
