摘要
We review recent studies by different experimental means of ultrathin films,exhibiting thickness-driven spin reorientation transitions(SRTs).The stage is set by determining,via phenomenological thermodynamic description,of the relevant phase diagrams for the possible types of SRT with and without applied magnetic field.Suitable representation may be chosen such that best use is made of the linear character(under thickness variation) of the system's path in anisotropy space.The latter involves higher-order bulk and surface anisotropies in a substantial way.We examine sensitive experimental techniques for the detection and quantification of SRTs,such as hysteresis measurements with magneto-optical Kerr effect(MOKE),micromagnetic studies utilizing scanning electron microscopy with polarization analysis(SEMPA),photoemission electron microscopy(PEEM) and spin-polarized low-energy electron microscopy(SPLEEM) as well as ac magnetic susceptibility measurements via MOKE.Key issues are conclusively discussed including the identification of reliable experimental fingerprints about whether a given SRT proceeds via a phase of coexistence or via a cone(canted) phase.We demonstrate how the application of the general theoretical ideas to carefully designed measurements leads to the determination of the most important material parameters in any ultrathin-film SRT,namely,the surface(interface) magnetic anisotropy constants.The review concludes by our personal outline for future promising work on SRTs.
We review recent studies by different experimental means of ultrathin films, exhibiting thickness-driven spin reorientation transitions （SRTs）. The stage is set by determining, via phenomenological thermodynamic description, of the relevant phase diagrams for the possible types of SRT with and without applied magnetic field. Suitable representation may be chosen such that best use is made of the linear character （under thickness variation） of the system＇s path in anisotropy space. The latter in- volves higher-order bulk and surface anisotropies in a substantial way. We examine sensitive experimental techniques for the detection and quantification of SRTs, such as hysteresis measurements with magneto-optical Kerr effect （MOKE）, micromag- netic studies utilizing scanning electron microscopy with polarization analysis （SEMPA）, photoemission electron microscopy （PEEM） and spin-polarized low-energy electron microscopy （SPLEEM） as well as ac magnetic susceptibility measurements via MOKE. Key issues are conclusively discussed including the identification of reliable experimental fingerprints about whether a given SRT proceeds via a phase of coexistence or via a cone （canted） phase. We demonstrate how the application of the general theoretical ideas to carefully designed measurements leads to the determination of the most important material pa- rameters in any ultrathin-film SRT, namely, the surface （interface） magnetic anisotropy constants. The review concludes by our personal outline for future promising work on SRTs.
基金
supported by the State Key Programme for Basic Research of China (Grant No. 2010CB923401)
National Natural Science Foundation of China (Grant Nos. 10834001,10974087 and 11023002)
Natural Science Foundation of Jiangsu (Grant No. BK2012300)
