Multi-Step Magnetic Switching in Single-Crystal Co2MnGe(001) Films
Abstract
Epitaxial thin films of Co2MnGe, a full Heusler alloy predicted to be a half-metallic ferromagnet, has been grown by MBE onto GaAs(001). The Co2MnGe(001) films exhibit very unusual switching behavior because of the hybrid magnetic anisotropy, consisting of cubic magnetocrystalline anisotropy and induced uniaxial anisotropy. As a result for the Co2MnGe(001) films, [110] is the easiest axis, [1-10] is the second easy axis, and two hard axes at 63 deg. from [110]. A rich variety of hysteresis loops, from single-loop, double-loops, to triple-loops, have been observed when the magnetic field H is applied at various angles beta with respect to the [110] axis. For beta < 63 deg., the magnetization M lies between the easiest axis and the hard axis. The hysteresis loops are single-loops, similar to those of uniaxial anisotropy. For beta > 63 deg., the magnetization M lies between the second-easy axis and the hard axis. As H is swept from positive to negative, M is rotated by about 90 deg. to lie between the easiest axis and the hard axis. The magnetization M is then rotated by nearly 180 deg., before it is finally rotated backward by nearly 90 deg. to lie between the second-easy axis and the hard axis, and opposite to the original orientation. We have developed a theoretical model using coherent rotation and the associated anisotropy energies that can quantitatively account for the rich variety of experimental results. Magneto-optical indicator film (MOIF) technique measurements show domain pattern and rotation of M that confirmed the theoretical model for the hysteresis behavior. Domain wall nucleation and propagation were also observed during magnetic switching. *Work supported by NSF grant No. DMR01-01814.
- Publication:
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APS March Meeting Abstracts
- Pub Date:
- March 2002
- Bibcode:
- 2002APS..MARF27004Y