Torque curve measurements in HCP Co in very low fields

Abstract

Magnetic torque measurements have been made for a single crystal of Co of hcp structure in a very low field region where the torque intensity was not saturated. I n this region it had been considered to be impossible to determine the magnetocrystalline anisotropy constants from observed torque curves. Recently, a new method of analyzing the torque curves was proposed by the present author with the help of a least mean square routine instead of the usual Fourier analysis. By using this method the first magnetocrystalline anisotropy constant Kul was, for the first time, determined at 77 K. It was found that the Kul determined in the low field range between 0.3 and 0.5 T coincides with the value determined at a high field region where the torque curve was saturated enough. Below 0.2 T the value of Kul decreased with decreasing the field. This region was found to correspond to the domain wall formation.

Magnetization process and torque curves in HCP cobalt

“…From this fact the actual demagnetization factor is estimated to be 0.28. This value is smaller than 0.46, which was estimated, previously [ 5 ] by considering an approximate ellipsoidal shape. The magnetization perpendicular to the c-axis became saturated above 1T.…”

Magnetic properties and nanostructure of FePt-TiN granular films deposited with N2 gas addition for heat assisted magnetic recording media

“…Torque curves were measured by using a physical property measurement system with a torque magnetometer option (Quantum Design, PPMS) with the maximum applied field of 90 kOe. 27) By taking into account the saturated torque coefficient with a twofold components (L 2θ sat ) and the self-energy caused by the demagnetizing field (2π(M s film ) 2 ), the perpendicular magnetic anisotropy of the film (K u⊥ ) was derived from the following equation: 27,28)…”

Investigations of low dimensional magnetic structures for memory and storage device applications

“…the torque curves of the pristine and ion-implanted samples. The pristine sample exhibits the periodicity of 180° of peaks in the torque curve, which signifies the presence of uniaxial anisotropy in the system [120]. Moreover, the appearance of the first peak in the first quadrant suggests that the OOP direction is the easy axis for this sample [120].…”

“…The pristine sample exhibits the periodicity of 180° of peaks in the torque curve, which signifies the presence of uniaxial anisotropy in the system [120]. Moreover, the appearance of the first peak in the first quadrant suggests that the OOP direction is the easy axis for this sample [120]. The occurrence of other less intense peaks in the torque curve of the pristine sample is the signature of the fact that there are some atomic moments, which are away from the easy axis (OOP) direction.…”

“…The fixed chirality induces more uniform and highly efficient DW motion [118]. Several other material systems such as synthetic antiferromagnets (SAF) and ferrimagnets have been studied and SOT was found to drive the DWs at much higher velocities [119][120][121]. The major achievements in DW dynamics research can be summarized in the following table.…”