The mechanisms of enhancing spin-orbit torque(SOT) have attracted significant attention, particularly regarding the influence of extrinsic scattering mechanisms on SOT efficiency, as they complement intrinsic contribu...The mechanisms of enhancing spin-orbit torque(SOT) have attracted significant attention, particularly regarding the influence of extrinsic scattering mechanisms on SOT efficiency, as they complement intrinsic contributions. In multilayer systems, extrinsic interfacial scattering, along with scattering from defects or impurities inside the materials, plays a crucial role in affecting the SOT efficiency. In this study, we successfully fabricated high-quality epitaxially grown [Ir/Pt]N superlattices with an increasing number of interfaces using a magnetron sputtering system to investigate the contribution of extrinsic interfacial scattering to SOT efficiency. We measured SOT efficiency through spin-torque ferromagnetic resonance methods and determined the spin Hall angle using the spin pumping technique. Additionally, we calculated spin transparency based on the SOT efficiency and spin Hall angle. Our findings indicate that the values of SOT efficiency, spin Hall angle, and spin transparency are enhanced in the superlattice structure compared to Pt, which we attribute to the increase in interfacial scattering.This research offers an effective strategy for designing and fabricating advanced spintronic devices.展开更多
Interface engineering is an effective and feasible method to regulate the magnetic anisotropy of films by altering interfacial states between films.Using the technique of pulsed laser deposition,we prepared La_(0.67)S...Interface engineering is an effective and feasible method to regulate the magnetic anisotropy of films by altering interfacial states between films.Using the technique of pulsed laser deposition,we prepared La_(0.67)Sr_(0.33)MnO_(3)(LSMO)and La_(0.67)Sr_(0.33)MnO_(3)/SrCoO_(2.5)(LSMO/SCO)films on(110)-oriented La_(0.3)Sr_(0.7)Al_(0.65)Ta_(0.35)O_(3) substrates.By covering the SCO film above the LSMO film,we transformed the easy magnetization axis of LSMO from the[001]axis to the[110]axis in the film plane.Based on statistical analyses,we find that the corresponding Mn-Mn ionic distances are different in the two types of LSMO films,causing different distortions of Mn-O octahedron in LSMO.In addition,it also induces diverse electronic occupation states in Mn^(3+)ions.The e_(g) electron of Mn^(3+)occupies 3z^(2)-r^(2) and x^(2)-y^(2) orbitals in the LSMO and LSMO/SCO,respectively.We conclude that the electronic spin reorientation leads to the transformation of the easy magnetization axis in the LSMO films.展开更多
Hydrogen is expected to be a metal at sufficient high pressures[1]while it can also be a high temperature superconductor based on BCS theory because of its high Debye temperature arising from the light mass of hydroge...Hydrogen is expected to be a metal at sufficient high pressures[1]while it can also be a high temperature superconductor based on BCS theory because of its high Debye temperature arising from the light mass of hydrogen[2].Since it is very challenging to reach the pressure for the hydrogen metallization,the “chemically precompressed” hydrogen-rich compounds were in turn proposed[3,4]to realize high temperature superconductivity at lower pressures.The experimental discovery of high temperature superconductivity[5]in SH3 has greatly stimulated efforts to explore new hydrogen-rich superconductors,such as in rare earth polyhydrides[6,7].展开更多
The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfu...The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique.The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity(SC).The superconducting transition with a maximum onset temperature(Tc)71 K was observed at pressure of 218 GPa in the experiments.The Tcdecreased to 65 K when pressure was at 181 GPa.From the evolution of SC at applied magnetic fields,the upper critical field at zero temperatureμ0Hc2(0)was obtained to be~36 T.The in-situ high pressure X-ray diffraction experiments imply that the high TcSC should arise from the Lu4H23phase with Pm3n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors.展开更多
The charge-trapping process, with HfO2 film as the charge-capturing layer, has been investigated by using in situ electron energy-loss spectroscopy and in situ energy-filter image under positive external bias. The res...The charge-trapping process, with HfO2 film as the charge-capturing layer, has been investigated by using in situ electron energy-loss spectroscopy and in situ energy-filter image under positive external bias. The results show that oxygen vacancies are non-uniformly distributed throughout the HfO2 trapping layer during the programming process. The distribution of the oxygen vacancies is not the same as that of the reported locations of the trapped electrons, implying that the trapping process is more complex. These bias-induced oxygen defects may affect the device performance characteristics such as the device lifetime. This phenomenon should be considered in the models of trapping processes.展开更多
Recently,cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts,cesium lead halide perovskites,owing to their low toxicity.However,the photophysics of cesium-bismuth halides nano...Recently,cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts,cesium lead halide perovskites,owing to their low toxicity.However,the photophysics of cesium-bismuth halides nanocrystals(NCs)have not yet been fully rationalized because their structures remain highly debated.The ultraviolet-visible(UV-vis)absorption along with other photophysical properties such as the nature and lifetime of the excited states vary considerably across the previous reports.Here,we successfully synthesize pure Cs_(3)BiBr_(6)and Cs_(3)Bi_(2)Br_(9)NCs via a modified hot-injection method,where the structure can be easily controlled by tuning the reaction temperature.The UV-vis absorption spectrum of the pure Cs_(3)Bi_(2)Br_(9)NCs features two characteristic peaks originating from the absorption of the first exciton and second exciton,respectively,which ultimately clarifies the debate in the previous reports.Using femtosecond transient absorption spectroscopy,we systematically investigate the excited state dynamics of the Cs_(3)Bi_(2)Br_(9)NCs and reveal that the photoexcited carriers undergo a self-trapping process within 3 ps after excitation.More intriguingly,the Cs_(3)Bi_(2)Br_(9)NCs prepared by this method show much better photostability than those prepared by the ligand-assisted reprecipitation process.Photodetectors based on these Cs_(3)Bi_(2)Br_(9)NCs show a sensitive light response,demonstrating the definite potential for breakthrough optoelectronic applications.展开更多
LiFeAs single crystal has been grown with superconducting transition temperature Tc comparable to that of polycrystals.A magnetic transition is found at about 160 K,which suggests the correlation of superconductivity ...LiFeAs single crystal has been grown with superconducting transition temperature Tc comparable to that of polycrystals.A magnetic transition is found at about 160 K,which suggests the correlation of superconductivity with spin wave density.展开更多
基金financially supported by the Science Center of the National Science Foundation of China (Grant No. 52088101)the National Natural Science Foundation of China (Grant Nos. 52161160334, 12274437, 12174426, and 52271237)+1 种基金the Chinese Academy of Sciences (CAS) Project for Young Scientists in Basic Research No. YSBR-084the CAS Youth Interdisciplinary Team。
文摘The mechanisms of enhancing spin-orbit torque(SOT) have attracted significant attention, particularly regarding the influence of extrinsic scattering mechanisms on SOT efficiency, as they complement intrinsic contributions. In multilayer systems, extrinsic interfacial scattering, along with scattering from defects or impurities inside the materials, plays a crucial role in affecting the SOT efficiency. In this study, we successfully fabricated high-quality epitaxially grown [Ir/Pt]N superlattices with an increasing number of interfaces using a magnetron sputtering system to investigate the contribution of extrinsic interfacial scattering to SOT efficiency. We measured SOT efficiency through spin-torque ferromagnetic resonance methods and determined the spin Hall angle using the spin pumping technique. Additionally, we calculated spin transparency based on the SOT efficiency and spin Hall angle. Our findings indicate that the values of SOT efficiency, spin Hall angle, and spin transparency are enhanced in the superlattice structure compared to Pt, which we attribute to the increase in interfacial scattering.This research offers an effective strategy for designing and fabricating advanced spintronic devices.
基金the National Key Research Program of China(Grant Nos.2017YFA0206200,2016YFA0300701,and2018YFA0208402)the National Natural Science Foundation of China(Grant Nos.11934017,11874413,11574376,and 51972333)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33030200)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(Grant No.2019009)。
文摘Interface engineering is an effective and feasible method to regulate the magnetic anisotropy of films by altering interfacial states between films.Using the technique of pulsed laser deposition,we prepared La_(0.67)Sr_(0.33)MnO_(3)(LSMO)and La_(0.67)Sr_(0.33)MnO_(3)/SrCoO_(2.5)(LSMO/SCO)films on(110)-oriented La_(0.3)Sr_(0.7)Al_(0.65)Ta_(0.35)O_(3) substrates.By covering the SCO film above the LSMO film,we transformed the easy magnetization axis of LSMO from the[001]axis to the[110]axis in the film plane.Based on statistical analyses,we find that the corresponding Mn-Mn ionic distances are different in the two types of LSMO films,causing different distortions of Mn-O octahedron in LSMO.In addition,it also induces diverse electronic occupation states in Mn^(3+)ions.The e_(g) electron of Mn^(3+)occupies 3z^(2)-r^(2) and x^(2)-y^(2) orbitals in the LSMO and LSMO/SCO,respectively.We conclude that the electronic spin reorientation leads to the transformation of the easy magnetization axis in the LSMO films.
基金supported by the National Natural Science Foundation of China,Ministry of Science and Technology of the People’s Republic of ChinaChinese Academy of Sciences through Research Projects(2018YFA0305700,11921004,and XDB33010200)。
文摘Hydrogen is expected to be a metal at sufficient high pressures[1]while it can also be a high temperature superconductor based on BCS theory because of its high Debye temperature arising from the light mass of hydrogen[2].Since it is very challenging to reach the pressure for the hydrogen metallization,the “chemically precompressed” hydrogen-rich compounds were in turn proposed[3,4]to realize high temperature superconductivity at lower pressures.The experimental discovery of high temperature superconductivity[5]in SH3 has greatly stimulated efforts to explore new hydrogen-rich superconductors,such as in rare earth polyhydrides[6,7].
基金supported by the Natural Science Foundation of Chinathe National Key R&D Program of ChinaChinese Academy of Sciences through research projects(Grant Nos.2018YFA0305700,2021YFA1401-800,and XDB33010200)。
文摘The binary polyhydrides of heavy rare earth lutetium that shares a similar valence electron configuration to lanthanum have been experimentally discovered to be superconductive.The lutetium polyhydrides were successfully synthesized at high pressure and high temperature conditions using a diamond anvil cell in combinations with the in-situ high pressure laser heating technique.The resistance measurements as a function of temperature were performed at the same pressure of synthesis in order to study the transitions of superconductivity(SC).The superconducting transition with a maximum onset temperature(Tc)71 K was observed at pressure of 218 GPa in the experiments.The Tcdecreased to 65 K when pressure was at 181 GPa.From the evolution of SC at applied magnetic fields,the upper critical field at zero temperatureμ0Hc2(0)was obtained to be~36 T.The in-situ high pressure X-ray diffraction experiments imply that the high TcSC should arise from the Lu4H23phase with Pm3n symmetry that forms a new type of hydrogen cage framework different from those reported for previous light rare earth polyhydride superconductors.
基金Acknowledgements This work was supported by the National Basic Research Program of China （Nos. 2012CB932302, 2010CB934202 and 2013CB932904）, the National Natural Science Foundation of China （No. 10974235）.
文摘The charge-trapping process, with HfO2 film as the charge-capturing layer, has been investigated by using in situ electron energy-loss spectroscopy and in situ energy-filter image under positive external bias. The results show that oxygen vacancies are non-uniformly distributed throughout the HfO2 trapping layer during the programming process. The distribution of the oxygen vacancies is not the same as that of the reported locations of the trapped electrons, implying that the trapping process is more complex. These bias-induced oxygen defects may affect the device performance characteristics such as the device lifetime. This phenomenon should be considered in the models of trapping processes.
基金supported by the National Key Research and Development Program of China(2020YFA0309300)the Natural Science Foundation of Tianjin(20JCZDJC00560 and 20JCJQJC00210)+2 种基金the National Natural Science Foundation of China(NSFC,11974191 and 12127803)the 111 Project(B07013)the“Fundamental Research Funds for the Central Universities”,Nankai University(91923139,63213040,C029211101,C02922101,and ZB22000104)。
文摘Recently,cesium bismuth halide perovskites have emerged as potential substitutes to their counterparts,cesium lead halide perovskites,owing to their low toxicity.However,the photophysics of cesium-bismuth halides nanocrystals(NCs)have not yet been fully rationalized because their structures remain highly debated.The ultraviolet-visible(UV-vis)absorption along with other photophysical properties such as the nature and lifetime of the excited states vary considerably across the previous reports.Here,we successfully synthesize pure Cs_(3)BiBr_(6)and Cs_(3)Bi_(2)Br_(9)NCs via a modified hot-injection method,where the structure can be easily controlled by tuning the reaction temperature.The UV-vis absorption spectrum of the pure Cs_(3)Bi_(2)Br_(9)NCs features two characteristic peaks originating from the absorption of the first exciton and second exciton,respectively,which ultimately clarifies the debate in the previous reports.Using femtosecond transient absorption spectroscopy,we systematically investigate the excited state dynamics of the Cs_(3)Bi_(2)Br_(9)NCs and reveal that the photoexcited carriers undergo a self-trapping process within 3 ps after excitation.More intriguingly,the Cs_(3)Bi_(2)Br_(9)NCs prepared by this method show much better photostability than those prepared by the ligand-assisted reprecipitation process.Photodetectors based on these Cs_(3)Bi_(2)Br_(9)NCs show a sensitive light response,demonstrating the definite potential for breakthrough optoelectronic applications.
基金supported by the National Natural Science Foundation of China and MOSt of China through Research Projects
文摘LiFeAs single crystal has been grown with superconducting transition temperature Tc comparable to that of polycrystals.A magnetic transition is found at about 160 K,which suggests the correlation of superconductivity with spin wave density.
