Influence of spin polarization enhancement layer to rare earth–transition metal thin films for perpendicular tunneling magnetoresistance evaluated by ferromagnetic Hall effect

Abstract

Fluctuation field and time dependence of magnetization in TbFeCo amorphous rare earth-transition metal thin films for perpendicular magnetic recording Magnetic properties of ion beam sputter-deposited TbFeCo and GdFeCo thin films with their compensation point were studied using ferromagnetic Hall effect measurement. Gd x ͑Fe 90 Co 10 ͒ 1−x thin films sputter deposited using Kr exhibited high squareness ratio and sharp magnetization reversal compared with those prepared using Ar as sputtering gas. Lower kinetic energy of sputtering ions was effective to attain higher squareness ratio. Ferromagnetic Hall effect clarifies the magnetization reversal process of a FeCo͑x nm͒ layer contacted to a TbFeCo͑50 nm͒ layer. FeCo layer with thickness less than 2 nm is magnetized together with TbFeCo layer. Ferromagnetic Hall measurement is a powerful tool to determine the magnetization process of very thin films and magnetically coupled layers.

Novel behaviors of anomalous Hall effect in TbFeCo ferrimagnetic thin films

“…Hatori et al reported that the anomalous Hall resistance of RE-rich sample has the negative sign of AHE while that of TM-rich sample has the positive sign at the room temperature. 9 The AHE signs of 50nm-and 20nm-thick TbFeCo samples at room temperature are in good agreement with the previous report. However, the AHE signs of 20nm-and 10nm-thick samples are reversed as the temperature increases, and the AHE sign of 5nm-thick sample remains positive even if the temperature changes.…”

“…The recent studies reported that the AHE sign in TbFeCo thin films is predominated by the TM moment. [9][10][11][12][13][14][15][16][17] These signs are originated from the spin orientations in RE-and TM-sites in RE-TM alloys near the compensation composition.…”

Exchange Bias and Coercivity in Vicinity of Magnetic Compensation Point in GdFeCo Amorphous Film

“…In HRE-TM amorphous films, the magnetic moments of the rare-earth ions are antiparallel to the moments of the transition metal. The PMA forms in the films with composition in the vicinity of the compensated ferrimagnetic state [35]. For the GdFeCo samples studied in this work, the FeCo magnetic sublattice is dominated at room temperature.…”

Effects of MgO Barrier Thickness on Magnetic Anisotropy Energy Constant in Perpendicular Magnetic Tunnel Junctions of (Co/Pd)$_{n}$/MgO/(Co/Pt)$_{n}$

“…The magnetic properties were measured using an alternating gradient magnetometer. The anisotropy energy constants were obtained by using the extraordinary Hall effect (EHE) measurements and taking the perpendicular Hall voltage signal with the external magnetic field parallel to the current direction [8]. Fig.…”