Precursor of a magnetic-field-induced liquid-liquid transition of oxygen

TL;DR

This study investigates how high magnetic fields affect liquid oxygen's acoustic properties, revealing fluctuations that suggest an impending liquid-liquid transition involving local structural changes.

Contribution

It provides experimental evidence of magnetic-field-induced fluctuations in liquid oxygen, indicating a precursor to a liquid-liquid transition not explained by classical theories.

Findings

Sound velocity decreases monotonically with magnetic field.

Acoustic attenuation increases significantly, up to 20 times the zero-field value.

Fluctuations suggest a transition from low- to high-susceptibility liquid states.

Abstract

The acoustic properties of liquid oxygen have been studied up to 90 T by means of the ultrasound pulse-echo technique. A monotonic decrease of the sound velocity and an asymptotic increase of the acoustic attenuation are observed by applying magnetic fields. An unusually large acoustic attenuation, that becomes 20 times as large as the zero-field value, cannot be explained by the classical theory. These results indicate strong fluctuations of antiferromagnetically coupled local structures. We point out that the observed fluctuations are a precursor of a liquid-liquid transition, from a low-susceptibility to a high-susceptibility liquid, which is characterized by a local-structure rearrangement.