Magnetic skyrmions in multilayer structures are considered as a new direction for the next generation of storage due to their small size,strong anti-interference ability,high current-driven mobility,and compatibility ...Magnetic skyrmions in multilayer structures are considered as a new direction for the next generation of storage due to their small size,strong anti-interference ability,high current-driven mobility,and compatibility with existing spintronic technology.In this work,we present a tunable room temperature skyrmion platform based on multilayer stacks of MgO/FeNiB/Mo.We systematically studied the creation of magnetic skyrmions in MgO/FeNiB/Mo multilayer structures with perpendicular magnetic anisotropy(PMA).In these structures,the magnetic anisotropy changes from PMA to in-plane magnetic anisotropy(IMA)as the thickness of FeNiB layer increases.By adjusting the applied magnetic field and electric current,stable and high-density skyrmions can be obtained in the material system.The discovery of this material broadens the exploration of new materials for skyrmion and promotes the development of spintronic devices based on skyrmions.展开更多
The origin of ferromagnetism in epitaxial strained LaCoO_(3-x)films has long been controversial.Here,we investigated the magnetic behavior of a series of oxygen vacancy-ordered LaCoO_(3-x)films on different substrates...The origin of ferromagnetism in epitaxial strained LaCoO_(3-x)films has long been controversial.Here,we investigated the magnetic behavior of a series of oxygen vacancy-ordered LaCoO_(3-x)films on different substrates.Obvious ferromagnetism was observed in perovskite LaCoO_(3)/LSAT(LSAT=(LaAlO_(3))0.3(SrAlTaO_(6))_(0.7))and LaCoO_(3)/SrTiO_(3) films,while LaCoO_(3)/LaAlO_(3)films showed weak ferromagnetic behavior.Meanwhile,LaCoO_(2.67) films exhibited antiferromagnetic behavior.An unexpected low-temperature ferromagnetic phenomenon with a Curie temperature of~83 K and a saturation magnetization of~1.2μB/Co was discovered in 15 nm thick LaCoO_(2.5)/LSAT thin films,which is probably related to the change in the interface CoO_(6) octahedron rotation pattern.Meanwhile,the observed ferromagnetism gradually disappeared as the thickness of the film increased,indicating a relaxation of tensile strain.Analysis suggests that the rotation and rhombohedral distortion of the CoO_(6) octahedron weakened the crystal field splitting and promoted the generation of the ordered high-spin state of Co^(2+).Thus the super-exchange effect between Co^(2+)(high spin state),Co^(2+)(low spin state)and Co^(2+)(high spin state)produced a low-temperature ferromagnetic behavior.However,compressive-strained LaCoO_(2.5)film on a LaAlO_(3)substrate showed normal anti-ferromagnetic behavior.These results demonstrate that both oxygen vacancies and tensile strain are correlated with the emergent magnetic properties in epitaxial LaCoO_(3-x)films and provide a new perspective to regulate the magnetic properties of transition oxide thin films.展开更多
Amorphous Sm-Co films with uniaxial in-plane anisotropy have great potential for application in information-storage media and spintronic materials.The most effective method to produce uniaxial inplane anisotropy is to...Amorphous Sm-Co films with uniaxial in-plane anisotropy have great potential for application in information-storage media and spintronic materials.The most effective method to produce uniaxial inplane anisotropy is to apply an in-plane magnetic field during deposition.However,this method inevitably requires more complex equipment.Here,we report a new way to produce uniaxial in-plane anisotropy by growing amorphous Sm-Co films onto(011)-cut single-crystal substrates in the absence of an external magnetic field.The tunable anisotropy constant,kA,is demonstrated with variation in the lattice parameter of the substrates.A kA value as high as about 3.3×10^4J·m^-3 was obtained in the amorphous Sm-Co film grown on a LaAlO3(011)substrate.Detailed analysis indicated that the preferential seeding and growth of ferromagnetic(FM)domains caused by the anisotropic strain of the substrates,along with the formed Sm-Co,Co-Co directional pair ordering,exert a substantial effect.This work provides a new way to obtain in-plane anisotropy in amorphous Sm-Co films.展开更多
基金Project supported by the National Basic Research Program of China (Grant No.2015CB921403)the National Key Research and Development Program of China (Grant No.2016YFA0300804)+2 种基金the National Natural Science Foundation of China (Grant Nos.51871236,11874408,51431009,92263202,and 51971240)the Science Center of the National Science Foundation of China (Grant No.52088101)the Strategic Priority Research Program (B,Grant No.XDB33030200)of the Chinese Academy of Sciences (CAS)。
文摘Magnetic skyrmions in multilayer structures are considered as a new direction for the next generation of storage due to their small size,strong anti-interference ability,high current-driven mobility,and compatibility with existing spintronic technology.In this work,we present a tunable room temperature skyrmion platform based on multilayer stacks of MgO/FeNiB/Mo.We systematically studied the creation of magnetic skyrmions in MgO/FeNiB/Mo multilayer structures with perpendicular magnetic anisotropy(PMA).In these structures,the magnetic anisotropy changes from PMA to in-plane magnetic anisotropy(IMA)as the thickness of FeNiB layer increases.By adjusting the applied magnetic field and electric current,stable and high-density skyrmions can be obtained in the material system.The discovery of this material broadens the exploration of new materials for skyrmion and promotes the development of spintronic devices based on skyrmions.
基金supported by the National Key Research and Development Program of China(Grant Nos.2020YFA0711502 and 2019YFA0704900)the National Natural Sciences Foundation of China(Grant Nos.52088101,51971240,and 11921004)the Key Program of the Chinese Academy of Sciences and the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB33030200)。
文摘The origin of ferromagnetism in epitaxial strained LaCoO_(3-x)films has long been controversial.Here,we investigated the magnetic behavior of a series of oxygen vacancy-ordered LaCoO_(3-x)films on different substrates.Obvious ferromagnetism was observed in perovskite LaCoO_(3)/LSAT(LSAT=(LaAlO_(3))0.3(SrAlTaO_(6))_(0.7))and LaCoO_(3)/SrTiO_(3) films,while LaCoO_(3)/LaAlO_(3)films showed weak ferromagnetic behavior.Meanwhile,LaCoO_(2.67) films exhibited antiferromagnetic behavior.An unexpected low-temperature ferromagnetic phenomenon with a Curie temperature of~83 K and a saturation magnetization of~1.2μB/Co was discovered in 15 nm thick LaCoO_(2.5)/LSAT thin films,which is probably related to the change in the interface CoO_(6) octahedron rotation pattern.Meanwhile,the observed ferromagnetism gradually disappeared as the thickness of the film increased,indicating a relaxation of tensile strain.Analysis suggests that the rotation and rhombohedral distortion of the CoO_(6) octahedron weakened the crystal field splitting and promoted the generation of the ordered high-spin state of Co^(2+).Thus the super-exchange effect between Co^(2+)(high spin state),Co^(2+)(low spin state)and Co^(2+)(high spin state)produced a low-temperature ferromagnetic behavior.However,compressive-strained LaCoO_(2.5)film on a LaAlO_(3)substrate showed normal anti-ferromagnetic behavior.These results demonstrate that both oxygen vacancies and tensile strain are correlated with the emergent magnetic properties in epitaxial LaCoO_(3-x)films and provide a new perspective to regulate the magnetic properties of transition oxide thin films.
基金supported by the National Key Research and Development Program of China(2017YFB0702702,2018YFA0305704,2016YFB700903,2017YFA0303601,and 2017YFA0206300)the National Natural Sciences Foundation of China(51531008,51771223,51590880,11674378,51971240,U1832219,and 11934016)+2 种基金the Inner Mongolia Science and Technology Major Project of China 2016the Strategic Priority Research Program(B)Key Programof the Chinese Academy of Sciences(CAS).
文摘Amorphous Sm-Co films with uniaxial in-plane anisotropy have great potential for application in information-storage media and spintronic materials.The most effective method to produce uniaxial inplane anisotropy is to apply an in-plane magnetic field during deposition.However,this method inevitably requires more complex equipment.Here,we report a new way to produce uniaxial in-plane anisotropy by growing amorphous Sm-Co films onto(011)-cut single-crystal substrates in the absence of an external magnetic field.The tunable anisotropy constant,kA,is demonstrated with variation in the lattice parameter of the substrates.A kA value as high as about 3.3×10^4J·m^-3 was obtained in the amorphous Sm-Co film grown on a LaAlO3(011)substrate.Detailed analysis indicated that the preferential seeding and growth of ferromagnetic(FM)domains caused by the anisotropic strain of the substrates,along with the formed Sm-Co,Co-Co directional pair ordering,exert a substantial effect.This work provides a new way to obtain in-plane anisotropy in amorphous Sm-Co films.
