Manipulating magnetic anisotropies of Co/MgO(001) ultrathin films via oblique deposition

Abstract

We present a systematic investigation of magnetic anisotropy induced by oblique deposition of Co thin films on MgO (001) substrates by molecular beam epitaxy at different deposition angles, i.e., 0 • , 30 • , 45 • , 60 • , and 75 • with respect to the surface normal. Low energy electron diffraction (LEED), surface magneto-optical Kerr effect (SMOKE), and anisotropic magnetoresistance (AMR) setups were employed to investigate the magnetic properties of cobalt films. The values of in-plane uniaxial magnetic anisotropy (UMA) constant K u and four-fold magnetocrystalline anisotropy constant K 1 were derived from magnetic torque curves on the base of AMR results. It was found that the value of K u increases with increasing deposition angle with respect to the surface normal, while the value of K 1 remains almost constant for all the samples. Furthermore, by using MOKE results, the K u values of the films deposited obliquely were also derived from the magnetization curves along hard axis. The results of AMR method were then compared with that of hard axis fitting method (coherent rotation) and found that both methods have almost identical values of UMA constant for each sample.

Anomalous anisotropic magnetoresistance in single-crystalline Co/SrTiO3(001) heterostructures*

“…Furthermore, the AMR under a non-saturated magnetic field is measured, where the magnetization direction is determined by the competition between the applied field and the magnetic anisotropy. [51][52][53][54] With 100-mT field, longitudinal AMR of I Co[110] and transverse AMR of I Co[100] are obtained in Fig. A1 (Appendix A: Supplementary materials).…”

Strong anti-strain capacity of CoFeB/MgO interface on electronic structure and state coupling

“…Tunneling magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) has been intensively studied because of the wide application of MTJs in spintronics, [1][2][3][4][5] such as magnetic random access memory, [6] high-frequency microwave sources, [7] and magnetic sensors. [8,9] Theoretically, the TMR ratio is directly related to the spin polarization of the tunneling electrons in ferromagnetic material (FM) electrodes [10] and the tunneling matrix elements of the spin electrons.…”