Unconventional spin polarization at Argon ion milled SrTiO3 Interfaces

TL;DR

This paper demonstrates that Argon ion milling creates a 2DEG at SrTiO3 interfaces with unconventional spin polarization, confirmed by spin-torque ferromagnetic resonance measurements and micromagnetic simulations, advancing oxide spintronics.

Contribution

It introduces a novel Ar+ ion milling technique to induce oxygen vacancies and generate a 2DEG with unique spin polarization at SrTiO3 interfaces.

Findings

Unconventional spin polarization observed at Argon ion-milled SrTiO3 interface.

Spin-torque ferromagnetic resonance confirms large spin polarization.

Micromagnetic simulations support experimental observations.

Abstract

Interfacial two-dimensional electron gas (2DEG) formed at the perovskite-type oxide, such as SrTiO3, has attracted significant attention due to its properties of ferromagnetism, superconductivity, and its potential application in oxide-based low-power consumption electronics. Recent studies have investigated spin-to-charge conversion at the STO interface with different materials, which could affect the efficiency of this 2DEG interface. In this report, we presented an Ar^+ ion milling method to create a 2DEG at STO directly by inducing oxygen vacancies. To quantify the spin-to-charge conversion of this interface, we measured the angular-dependent spin-torque ferromagnetic resonance (ST-FMR) spectra, revealing an unconventional spin polarization at the interface of Argon ion-milled STO and NiFe. Furthermore, a micromagnetic simulation for angular-dependent spin-torque ferromagnetic resonance (ST-FMR) has been performed, confirming the large unconventional spin polarization at the interface.