Exploring two-dimensional(2D)magnetic heterostructures is essential for future spintronic and optoelectronic devices.Herein,using first-principle calculations,stable ferromagnetic ordering and colorful electronic prop...Exploring two-dimensional(2D)magnetic heterostructures is essential for future spintronic and optoelectronic devices.Herein,using first-principle calculations,stable ferromagnetic ordering and colorful electronic properties are established by constructing the VS_(2)/C_(3)N van der Waals(vdW)heterostructure.Unlike the semiconductive properties with indirect band gaps in both the VS2 and C3N monolayers,our results indicate that a direct band gap with type-Ⅱband alignment and p-doping characters are realized in the spin-up channel of the VS_(2)/C_(3)N heterostructure,and a typical type-Ⅲband alignment with a broken-gap in the spin-down channel.Furthermore,the band alignments in the two spin channels can be effectively tuned by applying tensile strain.An interchangement between the type-Ⅱand type-Ⅲband alignments occurs in the two spin channels,as the tensile strain increases to 4%.The attractive magnetic properties and the unique band alignments could be useful for prospective applications in the next-generation tunneling devices and spintronic devices.展开更多
The recent discovery of two-dimensional (2D) van der Waals (vdWs) ferromagnetic crystals provides an ideal platform for fundamental understanding of 2D magnetism, as well as the applications of low-power spintronic de...The recent discovery of two-dimensional (2D) van der Waals (vdWs) ferromagnetic crystals provides an ideal platform for fundamental understanding of 2D magnetism, as well as the applications of low-power spintronic devices. The advances of vdWs heterostructures can couple the quasiparticle interaction between the 2D ferromagnetic material and others with engineered strain, chemistry, optical and electrical properties, providing an additional route to realize conceptual quantum phenomena and novel device functionalities.展开更多
Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering.In recent years,lift-off and transfer technology of the epitaxial oxide thin ...Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering.In recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations.Moreover,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical phenomena.In this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with 45.and 0.twist angles were assembled via water-etching and transfer process.The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO<110>.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°Sample.The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial anisotropy.This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.展开更多
Two-dimensional ferromagnetic van der Waals(2D vdW)heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic ...Two-dimensional ferromagnetic van der Waals(2D vdW)heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic layered materials,and for manipulating spin degree of freedom at the limit of few atomic layers,which empower next-generation spintronic and memory devices.However,to date,the electronic properties of 2D ferromagnetic heterostructures still remain elusive.Here,we report an unambiguous magnetoresistance behavior in CrI_(3)/graphene heterostructures,with a maximum magnetoresistance ratio of 2.8%.The magnetoresistance increases with increasing magnetic field,which leads to decreasing carrier densities through Lorentz force,and decreases with the increase of the bias voltage.This work highlights the feasibilities of applying two-dimensional ferromagnetic vdW heterostructures in spintronic and memory devices.展开更多
Realizing high-temperature ferromagnetism in two-dimensional(2D)semiconductor nanosheets is significant for their applications in next-generation magnetic and electronic nanodevices.Herein,this goal could be achieved ...Realizing high-temperature ferromagnetism in two-dimensional(2D)semiconductor nanosheets is significant for their applications in next-generation magnetic and electronic nanodevices.Herein,this goal could be achieved on a MoS_(2) Moirésuperlattice grown on the reduced graphene oxide(RGO)substrate by a hydrothermal approach.The as-synthesized bilayer MoS_(2) superlattice structure with rotating angle(ϕ=13°±1°)of two hexagonal MoS_(2) lattices,possesses outstanding ferromagnetic property and an ultra-high Curie temperature of 990 K.The X-ray absorption near-edge structure and ultraviolet photoelectron spectroscopies combined with density functional theory calculation indicate that the covalent interactions between MoS_(2) Moirésuperlattice and RGO substrate lead to the formation of interfacial Mo-S-C bonds and complete spin polarization of Mo 4d electrons near the Fermi level.This design could be generalized and may open up a possibility for tailoring the magnetism of other 2D materials.展开更多
The discoveries of ferromagnetic and ferroelectric two-dimensional(2D)materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories.This review focus...The discoveries of ferromagnetic and ferroelectric two-dimensional(2D)materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories.This review focuses on the latest 2D ferromagnetic and ferroelectric materials that have been most recently studied,including insulating ferromagnetic,metallic ferromagnetic,antiferromagnetic and ferroelectric 2D materials.The fundamental properties that lead to the long-range magnetic orders of 2D materials are discussed.The low Curie temperature(Tc)and instability in 2D systems limits their use in practical applications,and several strategies to address this constraint are proposed,such as gating and composition stoichiometry.A van der Waals(vdW)heterostructure comprising 2D ferromagnetic and ferroelectric materials will open a door to exploring exotic physical phenomena and achieve multifunctional or nonvolatile devices.展开更多
Fe/（Ga,Mn）As heterostructures were fabricated by all molecular-beam epitaxy.Double-crystal X-ray diffraction and high-resolution cross-sectional transmission electron micrographs show that the Fe layer has a well or...Fe/（Ga,Mn）As heterostructures were fabricated by all molecular-beam epitaxy.Double-crystal X-ray diffraction and high-resolution cross-sectional transmission electron micrographs show that the Fe layer has a well ordered crystal orientation and an abrupt interface.The different magnetic behavior between the Fe layer and（Ga, Mn）As layer is observed by superconducting quantum interference device magnetometry.X-ray photoelectron spectroscopy measurements indicate no Fe_2As and Fe-Ga-As compounds,i.e.,no dead magnetic layer at the interface, which strongly affects the magnetic proximity and the polarization of the Mn ion in a thin（Ga,Mn）As region near the interface of the Fe/（Ga,Mn）As heterostructure.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0207500)Natural Science Foundation of Henan Province,China(Grant No.202300410507)Key Research&Development and Promotion Projects in Henan Province,China(Grant No.212102210134).
文摘Exploring two-dimensional(2D)magnetic heterostructures is essential for future spintronic and optoelectronic devices.Herein,using first-principle calculations,stable ferromagnetic ordering and colorful electronic properties are established by constructing the VS_(2)/C_(3)N van der Waals(vdW)heterostructure.Unlike the semiconductive properties with indirect band gaps in both the VS2 and C3N monolayers,our results indicate that a direct band gap with type-Ⅱband alignment and p-doping characters are realized in the spin-up channel of the VS_(2)/C_(3)N heterostructure,and a typical type-Ⅲband alignment with a broken-gap in the spin-down channel.Furthermore,the band alignments in the two spin channels can be effectively tuned by applying tensile strain.An interchangement between the type-Ⅱand type-Ⅲband alignments occurs in the two spin channels,as the tensile strain increases to 4%.The attractive magnetic properties and the unique band alignments could be useful for prospective applications in the next-generation tunneling devices and spintronic devices.
文摘The recent discovery of two-dimensional (2D) van der Waals (vdWs) ferromagnetic crystals provides an ideal platform for fundamental understanding of 2D magnetism, as well as the applications of low-power spintronic devices. The advances of vdWs heterostructures can couple the quasiparticle interaction between the 2D ferromagnetic material and others with engineered strain, chemistry, optical and electrical properties, providing an additional route to realize conceptual quantum phenomena and novel device functionalities.
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFB3201800)Natural Science Foundation of China (Grant Nos. U22A2019, 91964109, 52372123)+3 种基金State Key Laboratory for Mechanical Behavior of Materials (No. 20222405)Innovation Capability Support Program of Shaanxi (Grant No. 2021TD-12)National 111 Project of China (B14040)support from the Instrumental Analysis Center of Xi’an Jiaotong University
文摘Manipulating strain mode and degree that can be applied to epitaxial complex oxide thin films have been a cornerstone of strain engineering.In recent years,lift-off and transfer technology of the epitaxial oxide thin films have been developed that enabled the integration of heterostructures without the limitation of material types and crystal orientations.Moreover,twisted integration would provide a more interesting strategy in artificial magnetoelectric heterostructures.A specific twist angle between the ferroelectric and ferromagnetic oxide layers corresponds to the distinct strain regulation modes in the magnetoelectric coupling process,which could provide some insight in to the physical phenomena.In this work,the La_(0.67)Sr_(0.33)MnO_(3)(001)/0.7Pb(Mg_(1/3)Nb_(2/3))O_(3)-0.3PbTiO_(3)(011)(LSMO/PMN-PT)heterostructures with 45.and 0.twist angles were assembled via water-etching and transfer process.The transferred LSMO films exhibit a fourfold magnetic anisotropy with easy axis along LSMO<110>.A coexistence of uniaxial and fourfold magnetic anisotropy with LSMO[110]easy axis is observed for the 45°Sample by applying a 7.2 kV cm^(−1)electrical field,significantly different from a uniaxial anisotropy with LSMO[100]easy axis for the 0°Sample.The fitting of the ferromagnetic resonance field reveals that the strain coupling generated by the 45°twist angle causes different lattice distortion of LSMO,thereby enhancing both the fourfold and uniaxial anisotropy.This work confirms the twisting degrees of freedom for magnetoelectric coupling and opens opportunities for fabricating artificial magnetoelectric heterostructures.
基金Project supported by the National Natural Science Foundation of China(Grant No.51872039)Science and Technology Program of Sichuan,China(Grant No.M112018JY0025).
文摘Two-dimensional ferromagnetic van der Waals(2D vdW)heterostructures have opened new avenues for creating artificial materials with unprecedented electrical and optical functions beyond the reach of isolated 2D atomic layered materials,and for manipulating spin degree of freedom at the limit of few atomic layers,which empower next-generation spintronic and memory devices.However,to date,the electronic properties of 2D ferromagnetic heterostructures still remain elusive.Here,we report an unambiguous magnetoresistance behavior in CrI_(3)/graphene heterostructures,with a maximum magnetoresistance ratio of 2.8%.The magnetoresistance increases with increasing magnetic field,which leads to decreasing carrier densities through Lorentz force,and decreases with the increase of the bias voltage.This work highlights the feasibilities of applying two-dimensional ferromagnetic vdW heterostructures in spintronic and memory devices.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.11975234,11775225,12075243,and 12005227)Users with Excellence Program of Hefei Science Center CAS(Nos.2019HSC-UE002,2020HSC-UE002,and 2020HSC-CIP013)+1 种基金Postdoctoral Science Foundation of China(Nos.2020TQ0316,2020M682041,and 2019M662202)The authors would like to thank BSRF,SSRF and NSRL for the synchrotron beamtime.This work was partially carried out at the USTC Center for Micro and Nanoscale Research and Fabrication.
文摘Realizing high-temperature ferromagnetism in two-dimensional(2D)semiconductor nanosheets is significant for their applications in next-generation magnetic and electronic nanodevices.Herein,this goal could be achieved on a MoS_(2) Moirésuperlattice grown on the reduced graphene oxide(RGO)substrate by a hydrothermal approach.The as-synthesized bilayer MoS_(2) superlattice structure with rotating angle(ϕ=13°±1°)of two hexagonal MoS_(2) lattices,possesses outstanding ferromagnetic property and an ultra-high Curie temperature of 990 K.The X-ray absorption near-edge structure and ultraviolet photoelectron spectroscopies combined with density functional theory calculation indicate that the covalent interactions between MoS_(2) Moirésuperlattice and RGO substrate lead to the formation of interfacial Mo-S-C bonds and complete spin polarization of Mo 4d electrons near the Fermi level.This design could be generalized and may open up a possibility for tailoring the magnetism of other 2D materials.
基金the National Natural Science Foundation of China(Nos.51602040 and 51872039)Science and Technology Program of Sichuan(No.M112018JY0025)Scientific Research Foundation for New Teachers of UESTC(No.A03013023601007).
文摘The discoveries of ferromagnetic and ferroelectric two-dimensional(2D)materials have dramatically inspired intense interests due to their potential in the field of spintronic and nonvolatile memories.This review focuses on the latest 2D ferromagnetic and ferroelectric materials that have been most recently studied,including insulating ferromagnetic,metallic ferromagnetic,antiferromagnetic and ferroelectric 2D materials.The fundamental properties that lead to the long-range magnetic orders of 2D materials are discussed.The low Curie temperature(Tc)and instability in 2D systems limits their use in practical applications,and several strategies to address this constraint are proposed,such as gating and composition stoichiometry.A van der Waals(vdW)heterostructure comprising 2D ferromagnetic and ferroelectric materials will open a door to exploring exotic physical phenomena and achieve multifunctional or nonvolatile devices.
基金supported by the National Natural Science Foundation of China(Nos.61076117,60836002)the Fundamental Research Funds for the Central Universities(No.11ML33)
文摘Fe/（Ga,Mn）As heterostructures were fabricated by all molecular-beam epitaxy.Double-crystal X-ray diffraction and high-resolution cross-sectional transmission electron micrographs show that the Fe layer has a well ordered crystal orientation and an abrupt interface.The different magnetic behavior between the Fe layer and（Ga, Mn）As layer is observed by superconducting quantum interference device magnetometry.X-ray photoelectron spectroscopy measurements indicate no Fe_2As and Fe-Ga-As compounds,i.e.,no dead magnetic layer at the interface, which strongly affects the magnetic proximity and the polarization of the Mn ion in a thin（Ga,Mn）As region near the interface of the Fe/（Ga,Mn）As heterostructure.
