Near-Surface Structural Phase Transition of SrTiO$_3$ Studied with Zero-Field $\beta$-Detected Nuclear Spin Relaxation and Resonance

TL;DR

This study uses zero-field $eta$-detected nuclear spin techniques to detect a surface-specific structural phase transition in SrTiO$_3$, revealing a higher transition temperature and random domain orientation near the surface.

Contribution

It introduces a sensitive local probe method to study surface phase transitions, showing a higher transition temperature and domain randomness in SrTiO$_3$ compared to bulk.

Findings

Surface transition temperature is ~150 K, 45 K higher than bulk.

Tetragonal domains are randomly oriented below the transition.

Zero-field $eta$-detected nuclear resonance effectively probes surface phenomena.

Abstract

We demonstrate that zero-field $\beta$-detected nuclear quadrupole resonance and spin relaxation of low energy $^8$Li can be used as a sensitive local probe of structural phase transitions near a surface. We find that the transition near the surface of a SrTiO$_3$ single crystal occurs at $T_c \sim 150$ K, i.e., 45 K higher than $T^{bulk}_c$, and that the tetragonal domains formed below $T_c$ are randomly oriented.