Phonon-driven tuning of exchange interactions in Y3Fe5O12

TL;DR

This study investigates how optical phonons influence exchange interactions in Y3Fe5O12 using first-principles calculations, revealing the microscopic mechanisms by which lattice vibrations modify magnetic properties.

Contribution

It provides a mode-resolved, microscopic understanding of phonon-driven tuning of exchange interactions in Y3Fe5O12 based on density functional theory and Wannier-based models.

Findings

Optical phonons modify superexchange pathways.

Lattice distortions affect Fe-O-Fe bond geometry.

Phonon modes impact magnetic exchange interactions.

Abstract

Yttrium iron garnet (Y3Fe5O12) is a prototypical ferrimagnetic insulator widely used in spin-wave and magnonic devices owing to its extremely low magnetic damping and long magnon propagation length, and recent experiments suggest that lattice vibrations can influence magnetic properties, motivating a microscopic understanding of how phonons modify exchange interactions. In this work, phonon-driven tuning of exchange interactions in Y3Fe5O12 is investigated from a mode-resolved perspective based on first-principles calculations. We focus on how optical phonons modify the dominant superexchange pathways and how lattice distortions affect the Fe-O-Fe bond geometry that governs the exchange interaction. To this end, phonon modes are computed from density functional theory, and the exchange interactions are evaluated from a Wannier-based tight-binding model and mapped onto a spin Hamiltonian, while displaced structures along individual infrared-active modes are used to quantify their impact on the magnetic interactions.