Spin-current probe for phase transition in an insulator

TL;DR

This paper introduces a novel, electric-based method using spin pumping to detect phase transitions in insulators, demonstrated through antiferromagnetic transition in ultra-thin CoO films, offering a practical alternative to neutron scattering.

Contribution

It presents a new spin-current based probe for phase transitions, enabling electric detection in small-scale devices, unlike traditional neutron scattering techniques.

Findings

Detected antiferromagnetic transition in ultra-thin CoO films

Demonstrated frequency-dependent spin-current transmission as a phase transition indicator

Provided a versatile, electric method for phase transition detection in nanoscale materials

Abstract

Spin fluctuation and transition have always been one of central topics of magnetism and condensed matter science. Experimentally, the spin fluctuation is found transcribed onto scattering intensity in the neutron scattering process, which is represented by dynamical magnetic susceptibility and maximized at phase transitions. Importantly, a neutron carries spin without electric charge, and it can bring spin into a sample without being disturbed by electric energy, although large facilities such as a nuclear reactor is necessary. Here we show that spin pumping, frequently used in nanoscale spintronic devices, provides a desktop micro probe for spin transition; spin current is a flux of spin without an electric charge and its transport reflects spin excitation. We demonstrate detection of antiferromagnetic transition in ultra-thin CoO films via frequency dependent spin-current transmission measurements, which provides a versatile probe for phase transition in an electric manner in minute devices.