Micrometer thick single crystal iron-garnet films on a diamagnetic buffer layer for cryogenic applications

TL;DR

This paper presents a novel method to produce ultra-low-loss, single crystal yttrium iron garnet films on a diamagnetic buffer, significantly reducing damping for cryogenic quantum applications.

Contribution

It introduces a new buffer-layer approach to grow high-quality YIG films with minimal damping, surpassing previous thin film performance for cryogenic use.

Findings

Achieved record low ferromagnetic resonance linewidths at cryogenic temperatures.

Demonstrated homogeneity and quality of YIG films on a diamagnetic buffer.

Showed the importance of interfacial engineering in magnetic material performance.

Abstract

This work advances the frontier of low-damping magnetic materials, directly addressing the demand for ultra-low-loss components in quantum computing and cryogenic electronics. Here we demonstrate a new approach to get single crystal micrometer-thick yttrium iron garnet (YIG) films with low damping through isolating and mitigating interfacial paramagnetic contributions of a paramagnetic substrate by a buffer-layer. The YIG films with the diamagnetic yttrium scandium gallium garnet buffer layer grown by liquid phase epitaxy on a gadolinium gallium substrate demonstrate homogeneity unprecedented for the thin planar YIG structures, yielding ferromagnetic resonance linewidths of 4.9 MHz at 4 K and 5.9 MHz at 16 mK, the lowest values reported to date. These results underscore the critical role of interfacial engineering in overcoming intrinsic material limitations, opening avenues for further optimization in spin-based technologies.