Tunable perpendicular anisotropic magnetoresistance in CoO/Co/Pt heterostructures

Transport properties of magnetron-sputtered CoO/Co/Pt heterostructures were investigated by physical property measurement system.Different types of magnetoresistance are observed in the heterostructures,including isotropic anisotropic magnetoresistance(AMR),AMR with geometric size effect,and interfacial effect.A reversal in sign of perpendicular AMR is found in the film CoO(3 nm)/Co(3 nm)/Pt(3 nm)compared to the film CoO(3 nm)/Co(3 nm)/CoO(3 nm),which is associated with Pt.Moreover,perpendicular AMR is tunable in the films CoO(3 nm)/Co(3 nm)/CoO(t)/Pt(3 nm)and CoO(3 nm)/Co(3 nm)/Pt(t)/CoO(3 nm)at will,with either positive or negative value,by varying the inserting layer thickness.The electronic structure information of the samples was measured by X-ray photoelectron spectroscopy(XPS).The spin-related transport and XPS results manifest that magnetic proximity effect,surface scattering,together with oxygen migration contribute to the tunable function of Pt.

Exchange effect and magneto-plasmon mode dispersion in an anisotropic two-dimensional electronic system

The exchange effect and the magneto-plasmon mode dispersion are studied theoretically for an anisotropic twodimensional electronic system in the presence of a uniform perpendicular magnetic field.Employing an effective lowenergy model with anisotropic effective masses,which is relevant for a monolayer of phosphorus,the exchange effect due to the electron-electron interaction is treated within the self-consistent Hartree-Fock approximation.The magnetoplasmon mode dispersion is obtained by solving a Bethe-Salpeter equation for the electron density-density correlation function within the ladder diagram approximation.It is found that the exchange effect is reduced in the anisotropic system in comparison with the isotropic one.The magneto-plasmon mode dispersion shows a clear dependence on the direction of the wave vector.

CoPt_3纳米线阵列的制备及特性研究

在具有纳米级孔洞的多孔氧化铝模板上,用电化学方法成功地制备了CoPt3纳米线有序阵列复合膜。分别用透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线衍射(XRD)、振动样品磁强计(VSM)和SQUID对样品进行了测试与表征。形貌观察和物相分析表明,模板中的CoPt3纳米线构成的阵列,排列均匀有序,长约1.5微米,直径35纳米;而纳米线中的CoPt3为L12无序结构。磁性研究表明,纳米线的无序晶体结构决定了纳米线阵列弱的磁晶各向异性;同时纳米线中部分小晶粒在400K左右表现出顺磁性,导致纳米线阵列居里温度的下降。比较低温和室温下的磁滞回线,低温下有大的矫顽力,从另一方面证明纳米线中的小晶粒确实存在相转变。