Hematite Thin Films Grown on Z-Cut and Y-Cut Lithium Niobate Piezoelectric Substrates by Pulsed Laser Deposition

TL;DR

This study reports the successful epitaxial growth of hematite thin films on lithium niobate substrates, revealing temperature-dependent spin reorientation and domain structures, advancing potential applications in magnonics and spintronics.

Contribution

First demonstration of epitaxial hematite thin films on y- and z-cut lithium niobate substrates using pulsed laser deposition, with insights into domain orientation and magnetic properties.

Findings

Films on y-cut LiNbO3 are single-crystalline and phase-pure.

Films on z-cut LiNbO3 show two in-plane rotated domains.

Both types exhibit temperature-dependent spin reorientation transition.

Abstract

Altermagnets are a newly identified class of materials that combine advantageous characteristics of both ferro- and antiferromagnets, making them highly promising for spintronic applications. Hematite has recently been identified as an altermagnetic material and exhibits several noteworthy properties, including a high N\'eel temperature, a temperature dependent spin reorientation transition (SRT) at the Morin temperature ($T_\mathrm{M}$), and low magnetic damping. In this work, we demonstrate the epitaxial growth of hematite thin films on y- and z-cut lithium niobate (LiNbO$_3$) substrates using pulsed laser deposition (PLD). LiNbO$_3$ as piezoelectric substrate is of particular interest as it enables the efficient excitation of surface acoustic waves (SAWs) with interdigital transducers. The different substrate cuts allow for different orientations of the N\'eel vector. Films grown on y-cut LiNbO3 are single-crystalline and single-phase, while those deposited on z-cut LiNbO$_3$ exhibit two distinct in-plane (ip) domains rotated 60{\deg} relative to each other. On both substrates, the hematite thin films exhibit a temperature dependent SRT which allows the antiferromagnetic N\'eel vector to be controlled. This study paves the way for the development of high-quality piezoelectric/altermagnetic hyprids for magnonics and spintronics.