Tunable spin-flop transition in artificial ferrimagnets

TL;DR

This paper demonstrates that artificial ferrimagnets can exhibit tunable spin-flop transitions at lower magnetic fields without anisotropy, enhancing their potential for antiferromagnetic spintronics applications.

Contribution

The study introduces a method to control the spin-flop transition in artificial ferrimagnets by adjusting exchange coupling, eliminating the need for anisotropy and reducing the transition field.

Findings

Transition field suppressed by two orders of magnitude using Pd spacers.

Artificial ferrimagnets exhibit anisotropy-free spin-flop transitions.

Exchange coupling tuning enables control over transition properties.

Abstract

Spin-flop transition (SFT) consists in a jump-like reversal of antiferromagnetic magnetic moments into a non-collinear state when the magnetic field increases above the critical value. Potentially the SFT can be utilized in many applications of a rapidly developing antiferromagnetic spintronics. However, the difficulty of using them in conventional antiferromagnets lies in (a) too large switching magnetic fields (b) the need for presence of a magnetic anisotropy, and (c) requirement to apply magnetic field along the correspondent anisotropy axis. In this work we propose to use artificial ferrimagnets in which the spin-flop transition occurs without anisotropy and the transition field can be lowered by adjusting exchange coupling in the structure. This is proved by experiment on artificial Fe-Gd ferrimagnets where usage of Pd spacers allowed us to suppress the transition field by two orders of magnitude.