The effect of inserted layers on the anomalous Hall effect and perpendicular magnetic anisotropy in Ta/CoFeB/MgO heterostructures

Minghua Li,Xiaotong Liu,Rongsheng Gao,Hui Shi,Xudan Zhang,Shuai Fang,Gang Han,Jinshuai Chen,Yixin Zhu,Shaolong Jiang,Guanghua Yu,Jiafang Li

doi:10.1063/1.5019988

Abstract

In this work, Ta/M/CoFeB/MgO/Ta multilayers were designed to investigate the effect of M insertion on the anomalous Hall effect (AHE) and perpendicular magnetic anisotropy (PMA). Once inserted, Bi did not remain at the interface of Ta and CoFeB; it migrated to the surface of the films, which was not beneficial to PMA. X-ray photoelectron spectroscopic analyses revealed that the segregation of Ta was partly suppressed by the insertion of an Mo, Hf or Pt layer. However, the formation of a CoPt (or FePt) alloy decreased the PMA in the case of a Pt layer. The sample with Hf and Mo still exhibited a clear PMA after annealing at a 350 and 500 °C, respectively.

Highlights

The anomalous Hall effect (AHE) in ferromagnetic materials has attracted extensive attention due to its controversial mechanisms[1] and potential applications in electronics devices.[2]
Ta/M/CoFeB/MgO/Ta multilayers were designed to investigate the effect of M insertion on the AHE and perpendicular magnetic anisotropy (PMA) in CoFeB/MgO multilayers
The AHE and PMA are influenced by introducing a Mo and Hf metal layer at the Ta/CoFeB interface, and, more importantly, thermally stable AHE and PMA features are obtained in multilayers, due to interface modification

Summary

INTRODUCTION

The anomalous Hall effect (AHE) in ferromagnetic materials has attracted extensive attention due to its controversial mechanisms[1] and potential applications in electronics devices.[2]. Ferromagnetic materials with the AHE are potential candidates for practical applications in the field of magnetic sensors, memories, and logic devices.[10,11,12] With the development of spintronics, AHE has been studied in FM/NM layered structures such as Co/Au, Co/Pd, Co/Cu, and Co/Pt multilayers.[13,14,15,16] Currently, CoFeB/MgO multilayers have been used for the design of AHE-based devices,[17] while it is difficult for them to show thermally stable AHE and PMA simultaneously, due to elements interdiffusion during annealing.[18,19] it is necessary to make CoFeB/MgO multilayers exhibit thermally stable AHE and PMA features by material design for applications of AHE-based devices.

EXPERIMENTAL

RESULTS AND DISCUSSION

CONCLUSIONS