Electrically induced ferromagnetism in an irradiated complex oxide

TL;DR

This paper demonstrates that focused ion beam irradiation can induce ferromagnetism in a manganite, and electric stimuli can reversibly switch its phase between insulating and metallic states, enabling potential spintronic and neuromorphic applications.

Contribution

It reveals a novel way to electrically trigger ferromagnetism in irradiated complex oxides, contrasting with typical magnetic suppression in phase transitions.

Findings

Irradiation increases resistivity and suppresses ferromagnetism.

Electric stimuli induce a reversible insulator-to-metal transition.

The metallic phase exhibits ferromagnetism with anisotropic magnetoresistance.

Abstract

In metal-insulator transition materials, a small perturbation can shift the delicate balance between competing or coexisting electronic phases, leading to dramatic changes of the material's properties. Using La0.7Sr0.3MnO3, a prototypical metal-insulator transition manganite, we show that local low-dose focused ion beam irradiation increases resistivity by several orders of magnitude, converting the ferromagnetic-metal ground state into a paramagnetic-insulator. Surprisingly, we found that applying electric stimuli to the irradiated material induces a non-thermal insulator-to-metal transition, which results in low-power, repeatable volatile resistive switching. Magnetotransport measurements revealed that this voltage-induced metallic phase in the irradiated material is ferromagnetic, exhibiting clear anisotropic magnetoresistance. This work, thus, reports the discovery of a unique material in which the electrical triggering of the electronic phase transition results in the onset of magnetism, in stark contrast to the magnetic order suppression commonly observed in other metal-insulator transition switching materials. We demonstrate that local focused ion beam irradiation provides new and exciting opportunities to engineer electronic and magnetic functionalities that can find practical applications ranging from spintronics to neuromorphic hardware.