In-Situ Manipulation of Superconducting Properties via Ultrasonic Excitation

TL;DR

This study demonstrates that ultrasonic excitation can in-situ modify the critical temperature and magnetic properties of superconductors, revealing a non-linear coupling mechanism and the role of spin-orbit interactions.

Contribution

It introduces a novel method to manipulate superconducting properties using ultrasonic waves and elucidates the underlying non-thermal coupling mechanisms involved.

Findings

Ultrasonic excitation reduces $T_S$ with a power law dependence.

Behavior observed in both conventional and cuprate superconductors.

Localized heating effects are negligible below 10 V$_{pp}$ ultrasonic amplitude.

Abstract

We demonstrate in-situ manipulation of the critical temperature ($T_S$) and upper critical field ($H_{C2}$) of conventional and unconventional superconductors via ultrasonic excitation. Using an AC susceptibility measurements, we observed a reduction in $T_S$ with increasing amplitude of the applied ultrasonic waves. This reduction exhibits a power law dependence on the excitation voltage, suggesting a non-linear coupling between the ultrasonic waves and the superconducting order parameter. Analogous behavior was observed in cuprate superconductors, hinting at a possible link between the modified superconducting properties and the modulation of the antiferromagnetic network by ultrasonic excitation. Measurements on a paramagnetic material (Gd$_2$O$_3$) with quenched orbital angular momentum (L\,=\,0) revealed no change in magnetization even at extreme ultrasonic excitation amplitudes. This highlights the role of spin-orbit coupling in the observed effects and rules out the possibility of local temperature increases affecting the measurements. To further confirm this, we conducted auxiliary experiments where a Cernox temperature sensor was subjected to ultrasonic excitation, and the resulting temperature difference relative to a reference Cernox was recorded. Simultaneously, the power difference was measured to assess the impact of ultrasonic heating. This analysis revealed that localized heating effects become dominant above an ultrasonic amplitude of 10 V$_{pp}$.