The magnetic interface forward and inversion method is realized using the Taylor series expansion to linearize the Fourier transform of the exponential function. With a large expansion step and unbounded neighborhood,...The magnetic interface forward and inversion method is realized using the Taylor series expansion to linearize the Fourier transform of the exponential function. With a large expansion step and unbounded neighborhood, the Taylor series is not convergent, and therefore, this paper presents the magnetic interface forward and inversion method based on Pade approximation instead of the Taylor series expansion. Compared with the Taylor series, Pade's expansion's convergence is more stable and its approximation more accurate. Model tests show the validity of the magnetic forward modeling and inversion of Pade approximation proposed in the paper, and when this inversion method is applied to the measured data of the Matagami area in Canada, a stable and reasonable distribution of underground interface is obtained.展开更多
Recent advances in the study of exchange couplings in magnetic films are introduced.To provide a comprehensive understanding of exchange coupling,we have designed different bilayers,trilayers and multilayers,such as a...Recent advances in the study of exchange couplings in magnetic films are introduced.To provide a comprehensive understanding of exchange coupling,we have designed different bilayers,trilayers and multilayers,such as anisotropic hard/soft-magnetic multilayer films,ferromagnetic/antiferromagnetic/ferromagnetic trilayers,[Pt/Co]/NiFe/NiO heterostructures,Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide(AAO) template.The exchange-coupling interaction between soft-and hard-magnetic phases,interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer,ferromagnetic layer,and antiferromagnetic layer.Some particular physical phenomena have been observed and explained.展开更多
On the basis of first principles calculations, we report that the type and density of charge carriers of epitaxial graphene on SiC(O001) can be deliberately controlled by decorating the buffer layer with specific at...On the basis of first principles calculations, we report that the type and density of charge carriers of epitaxial graphene on SiC(O001) can be deliberately controlled by decorating the buffer layer with specific atoms (i.e., F, C1, O, or N). More importantly, a fine tuning of the doping behavior from intrinsic n-type to charge neutrality to p-type and interface magnetism is achieved via increasing the doping concentration of F atoms on the buffer layer. Our results suggest an interesting avenue to the application of epitaxial graphene in nanoscale electronic and spintronic devices.展开更多
The CoCr/Pt bilayers and (CoCr/Pt)_(20) multilayers with Pt underlayer wereprepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magneticanisotropy were investigated. The results show...The CoCr/Pt bilayers and (CoCr/Pt)_(20) multilayers with Pt underlayer wereprepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magneticanisotropy were investigated. The results show that the thickness of Pt under-layer has a greateffect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and(CoCr/Pt)_(20) multilayers. When the thickness of Pt underlayer increases, Pt(lll) and CoCr(002)peaks of both CoCr/Pt bilayers and (CoCr/Pt)_(20) multilayers increase and the bilayer periodicityof the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)_(20) multilayers withPt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)_(20) multilayers has astronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to theinterface magnetic anisotropy of the multilayers.展开更多
The first-principles calculations are employed to investigate the stability, magnetic, and electrical properties of the oxide heterostructure of LaAIO3/SrTiO3 (110). By comparing their interface energies, it is obta...The first-principles calculations are employed to investigate the stability, magnetic, and electrical properties of the oxide heterostructure of LaAIO3/SrTiO3 (110). By comparing their interface energies, it is obtained that the buckled interface is more stable than the abrupt interface. This result is consistent with experimental observation. At the interface of LaAIO3/SrTiO3 (110) heterostructure, the Ti-O octahedron distortions cause the Ti tzg orbitals to split into the two- fold degenerate dxz/dyz and nondegenerate dxy orbitals. The former has higher energy than the latter. The partly filled two-fold degenerate t2g orbitals are the origin of two-dimensional electron gas, which is confined at the interface. Lattice mismatch between LaA103 and SrTiO3 leads to ferroelectric-like lattice distortions at the interface, and this is the origin of spin-splitting of Ti 3d electrons. Hence the magnetism appears at the interface of LaAIO3/SrTiO3 (110).展开更多
An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the ...An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.展开更多
Our recent research achievements in the perpendicular magnetic anisotropy (PMA) properties of the CoFeB sand- wiched by MgO and tantalum layers are summarized. We found that the PMA behaviors of Ta/CoFeB/MgO and MgO...Our recent research achievements in the perpendicular magnetic anisotropy (PMA) properties of the CoFeB sand- wiched by MgO and tantalum layers are summarized. We found that the PMA behaviors of Ta/CoFeB/MgO and MgO/CoFeB/Ta thin films are different. The larger PMA in the latter film is related to the lower magnetization of CoFeB deposited on MgO. Furthermore, we have demonstrated a large anomalous Hall effect in perpendicular CoFeB thin fihn. Our results show large anomalous Hall resistivity, large longitudinal resistivity, and low switching field can be achieved, all at the same time, in the perpendicular CoFeB thin film. Anomalous Hall effect with high and linear sensitivity is also found in an MgO/CoFeBFFa thin film with a thick MgO layer, which opens a door tbr future device applications of perpendicular ferromagnetic thin films.展开更多
基金supported by Sino Probe-09-01-Integrated geophysical data processing and integrated system for moving platform(No.201311192)Graduate innovation fund of Jilin University(No.2015025)
文摘The magnetic interface forward and inversion method is realized using the Taylor series expansion to linearize the Fourier transform of the exponential function. With a large expansion step and unbounded neighborhood, the Taylor series is not convergent, and therefore, this paper presents the magnetic interface forward and inversion method based on Pade approximation instead of the Taylor series expansion. Compared with the Taylor series, Pade's expansion's convergence is more stable and its approximation more accurate. Model tests show the validity of the magnetic forward modeling and inversion of Pade approximation proposed in the paper, and when this inversion method is applied to the measured data of the Matagami area in Canada, a stable and reasonable distribution of underground interface is obtained.
基金Project supported by the National Basic Research Program of China (Grant No. 2010CB934603)Ministry of Science and Technology of China and the National Natural Science Foundation of China (Grant Nos. 50931006,50971123,and 51271177)
文摘Recent advances in the study of exchange couplings in magnetic films are introduced.To provide a comprehensive understanding of exchange coupling,we have designed different bilayers,trilayers and multilayers,such as anisotropic hard/soft-magnetic multilayer films,ferromagnetic/antiferromagnetic/ferromagnetic trilayers,[Pt/Co]/NiFe/NiO heterostructures,Co/NiO and Co/NiO/Fe trilayers on an anodic aluminum oxide(AAO) template.The exchange-coupling interaction between soft-and hard-magnetic phases,interlayer and interfacial exchange couplings and magnetic and magnetotransport properties in these magnetic films have been investigated in detail by adjusting the magnetic anisotropy of ferromagnetic layers and by changing the thickness of the spacer layer,ferromagnetic layer,and antiferromagnetic layer.Some particular physical phenomena have been observed and explained.
基金supported by the National Natural Science Foundation of China(Grant Nos.61335006,61378073,and 61527817)the Beijing Municipal Science and Technology Committee,China(Grant No.Z151100003315006)Fundamental Research Funds for the Central Universities of Beijing Jiaotong University,China(Grant No.2012YJS123)
文摘On the basis of first principles calculations, we report that the type and density of charge carriers of epitaxial graphene on SiC(O001) can be deliberately controlled by decorating the buffer layer with specific atoms (i.e., F, C1, O, or N). More importantly, a fine tuning of the doping behavior from intrinsic n-type to charge neutrality to p-type and interface magnetism is achieved via increasing the doping concentration of F atoms on the buffer layer. Our results suggest an interesting avenue to the application of epitaxial graphene in nanoscale electronic and spintronic devices.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50301002) and the New Star Plan of Science and Technology of Beijing (No.H020821290120)
文摘The CoCr/Pt bilayers and (CoCr/Pt)_(20) multilayers with Pt underlayer wereprepared by DC magnetron sputtering. The effects of prepared condition on perpendicular magneticanisotropy were investigated. The results show that the thickness of Pt under-layer has a greateffect on the microstructure and perpendicular magnetic anisotropy of CoCr/Pt bilayers and(CoCr/Pt)_(20) multilayers. When the thickness of Pt underlayer increases, Pt(lll) and CoCr(002)peaks of both CoCr/Pt bilayers and (CoCr/Pt)_(20) multilayers increase and the bilayer periodicityof the multilayers is improved. The effective magnetic anisotropy of (CoCr/Pt)_(20) multilayers withPt underlayer was much larger than that of CoCr/Pt bilayers. The (CoCr/Pt)_(20) multilayers has astronger perpendicular magnetic anisotropy than that of CoCr/Pt bilayers. This is ascribed to theinterface magnetic anisotropy of the multilayers.
基金Project supported by the National Basis Research Program of China(Grant No.2013CB632506)the National Natural Science Foundation of China(Grant Nos.11374186,51231007,and 51202132)the Independent Innovation Foundation of Shandong University,China(Grant No.2012TS027)
文摘The first-principles calculations are employed to investigate the stability, magnetic, and electrical properties of the oxide heterostructure of LaAIO3/SrTiO3 (110). By comparing their interface energies, it is obtained that the buckled interface is more stable than the abrupt interface. This result is consistent with experimental observation. At the interface of LaAIO3/SrTiO3 (110) heterostructure, the Ti-O octahedron distortions cause the Ti tzg orbitals to split into the two- fold degenerate dxz/dyz and nondegenerate dxy orbitals. The former has higher energy than the latter. The partly filled two-fold degenerate t2g orbitals are the origin of two-dimensional electron gas, which is confined at the interface. Lattice mismatch between LaA103 and SrTiO3 leads to ferroelectric-like lattice distortions at the interface, and this is the origin of spin-splitting of Ti 3d electrons. Hence the magnetism appears at the interface of LaAIO3/SrTiO3 (110).
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12074189,11704191,11774160,and 61427812)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20192006 and BK20211144)the Postdoctoral Research Funding Program of Jiangsu Province,China(Grant No.2021K503C)。
文摘An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.
基金Project supported by the National Basic Research Program of China(Grant No.2012CB933102)the National Natural Science Foundation of China(Grant Nos.50871120,11079052,and 11174354)
文摘Our recent research achievements in the perpendicular magnetic anisotropy (PMA) properties of the CoFeB sand- wiched by MgO and tantalum layers are summarized. We found that the PMA behaviors of Ta/CoFeB/MgO and MgO/CoFeB/Ta thin films are different. The larger PMA in the latter film is related to the lower magnetization of CoFeB deposited on MgO. Furthermore, we have demonstrated a large anomalous Hall effect in perpendicular CoFeB thin fihn. Our results show large anomalous Hall resistivity, large longitudinal resistivity, and low switching field can be achieved, all at the same time, in the perpendicular CoFeB thin film. Anomalous Hall effect with high and linear sensitivity is also found in an MgO/CoFeBFFa thin film with a thick MgO layer, which opens a door tbr future device applications of perpendicular ferromagnetic thin films.