Abstract
It is challenging to determine domain wall pinning energy and magnetic anisotropy since both coherent rotation and domain wall displacement coexist during magnetization switching process. Here, angular dependence anisotropic magnetoresistance (AMR) measurements at different magnetic fields were employed to determine magnetic anisotropy constants and domain wall pinning energy of Fe/MgO(001) ultrathin film. The AMR curves at magnetic fields which are high enough to ensure the coherent rotation of magnetization indicate a smooth behavior without hysteresis between clockwise (CW) and counter-clockwise (CCW) rotations. By analyzing magnetic torque, the magnetic anisotropy constants can be obtained. On the other hand, the AMR curves at low fields show abrupt transitions with hysteresis between CW and CCW rotations, suggesting the presence of multi-domain structures. The domain wall pinning energy can be obtained by analyzing different behaviors of AMR. Our work suggests that AMR measurements can be employed to figure out precisely the contributions of magnetic anisotropy and domain wall pinning energy, which is still a critical issue for spintronics.
Highlights
It is challenging to investigate the domain wall pinning energy and magnetic anisotropy of Fe/MgO(001) film simultaneously by a single method since both coherent rotation and domain wall displacement coexist during magnetization switching process
The hysteresis loop of Fe/Mg(001) film characterized by longitudinal magneto-optical Kerr effect (MOKE) exhibits two-jump magnetization switching process, which can be observed in other literature in the case of KU/K1 < 19
In order to deduce magnetic anisotropy constants and domain wall pinning energy, the current is applied at an angle of 6.3° with respect to the hard axis (Fe[110]) direction) for anisotropic magnetoresistance (AMR) measurements
Summary
It is challenging to investigate the domain wall pinning energy and magnetic anisotropy of Fe/MgO(001) film simultaneously by a single method since both coherent rotation and domain wall displacement coexist during magnetization switching process. The angular dependence anisotropic magnetoresistance (AMR) measurement was introduced to investigate magnetization switching process in Fe(001) film on MgO(001) substrate. By carefully analyzing angular dependence AMR at high fields and low fields, the magnitudes of additional UMA and four-fold magnetic anisotropy constants as well as the values of domain wall pinning energy can be obtained, respectively. The contributions of magnetic anisotropy and domain wall pinning energy of Fe/MgO(001) film can be probed precisely by AMR measurements in our work
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