Topological phonons in an inhomogeneously strained silicon-6: Possible evidence of the high temperature spin superfluidity and the second sound of topological phonons

TL;DR

This study provides experimental evidence of spin superfluidity and second sound in inhomogeneously strained silicon-6, revealing novel topological phonon behaviors and their potential for advanced spintronic applications.

Contribution

It reports the first experimental observation of spin superfluidity and second sound in strained silicon, linking topological phonons to magnetic phenomena.

Findings

Resonance in non-local resistance at 10 kHz and 270-281.55 K

Spatially varying non-local resistance phase observed

Evidence of standing wave behavior from topological phonons

Abstract

The superposition of topological phonons and flexoelectronic charge separation in an inhomogeneously strain Si give rise to topological electronic magnetism of phonons. The topological electronic magnetism of phonons is also expected to give rise to stationary spin current or spin superfluidity. In this experimental study, we present possible evidence of spin superfluidity in an inhomogeneously strained p-Si thin films samples. The spin superfluidity is uncovered using non-local resistance measurement. A resonance behavior is observed in a non-local resistance measurement at 10 kHz and between 270 K and 281.55 K, which is attributed to the second sound. The observation of second sound and spatially varying non-local resistance phase are the evidences for spin superfluidity. The spatially varying non-local resistance with opposite phase are also observed in Pt/MgO/p-Si sample. The overall non-local responses can be treated as a standing waveform from temporal magnetic moments of the topological phonons.