Welp U, Vlasko-Vlasov V K, Liu X, Furdyna J K, Wojtowicz T
Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA.
Phys Rev Lett. 2003 Apr 25;90(16):167206. doi: 10.1103/PhysRevLett.90.167206. Epub 2003 Apr 24.
Large, well-defined magnetic domains, on the scale of hundreds of micrometers, are observed in Ga1-xMn(x)As epilayers using a high-resolution magneto-optical imaging technique. The orientations of the magnetic moments in the domains clearly show in-plane magnetic anisotropy, which changes through a second-order transition from a biaxial mode (easy axes nearly along [100] and [010]) at low temperatures to an unusual uniaxial mode (easy axis along [110]) as the temperature increases above about T(c)/2. This transition is a result of the interplay between the natural cubic anisotropy of the GaMnAs zinc-blende structure and a uniaxial anisotropy which attribute to the effects of surface reconstruction.
利用高分辨率磁光成像技术，在Ga1-xMn(x)As外延层中观察到了尺寸达数百微米的、清晰界定的大磁畴。磁畴中磁矩的取向清楚地表明了面内磁各向异性，这种各向异性通过二级转变发生变化，即从低温下的双轴模式（易轴几乎沿[100]和[010]）转变为温度升高至约T(c)/2以上时的异常单轴模式（易轴沿[110]）。这种转变是GaMnAs闪锌矿结构的自然立方各向异性与归因于表面重构效应的单轴各向异性之间相互作用的结果。
