Field-Free and Energy-Efficient Switching of a Ferrimagnetic Insulator Through Orbital Currents of Copper

Abstract

Electrically manipulating the magnetization of insulators presents exciting opportunities for fast and energy-efficient spintronic devices. However, the existing approaches, which rely on spin-orbit torque (SOT), invariably require an auxiliary field. Here field-free current-induced magnetization switching in perpendicularly magnetized Tm3Fe5O12 films is demonstrated. This is achieved through a magnetic hybrid structure, Tm3Fe5O12/Co40Fe40B20/Cu/SiO2, where the Cu layer acts as the source of orbital current, and the in-plane magnetized Co40Fe40B20 layer functions as the converter of orbital-to-spin current. The interplay between the insulating and metallic magnetic layers not only yields a significant anomalous Hall signal for monitoring the Tm3Fe5O12 magnetization states, but also enables field-free switching that is immune to the magnetic history of the structure. It also observes similar Tm3Fe5O12 switching in stacks with different spin/orbital current sources, with the SOT-driven switching consuming substantially more power. This work establishes a pathway for achieving energetically efficient all-electrical manipulation of insulator spins through orbital currents.