Anomalous Magneto Transport in amorphous TbFeCo thin films*

TbFeCo has attracted some interests because of its high perpendicular anisotropy and tunable magnetic properties for nanomagnetic and spintronics application. In this study, we report a strong size dependence of the coercive field in 30 nm-thick Tb$_{30}$Fe$_{63.5}$Co$_{6.5 }$films with MgO capping. Magneto Optical Kerr effect (MOKE) and Vibrating Sample Magnetometer are performed on unpatterned films. The films exhibited strong PMA characteristics with M$_{S} \quad \sim $200 emu/cc, H$_{C}\sim $6000 Oe, and K$_{U} \quad \sim $ 5 x 10$^{6 }$erg/cc. The films were then fabricated into Hall bars with 500 nm, 50 $\mu $m and 500 $\mu $m in width. From anomalous Hall effect (AHE), H$_{C}$ was determined for these patterned films. For Hall bars with the width less than 50 $\mu $m, an increase in the coercivity field ($\sim $ 1.4 Tesla) was observed at room temperature. The temperature dependent of AHE was characterized from 50K to 300K. The thickness and composition dependent will also be studied and discussed.