# Phonon-mediated spin-flipping mechanism in the spin ices Dy$_2$Ti$_2$O$_7$ and Ho$_2$Ti$_2$O$_7$

## TL;DR

This study investigates phonon-mediated spin-flipping mechanisms in spin ices Dy$_2$Ti$_2$O$_7$ and Ho$_2$Ti$_2$O$_7$, providing a quantitative model for high-temperature spin dynamics supported by experimental evidence.

## Contribution

It introduces a constrained model of phonon-mediated spin flipping that explains high-temperature spin dynamics in these materials, supported by experimental coupling evidence.

## Key findings

- Quantitative model of phonon-mediated spin flipping
- Experimental evidence of crystal field and phonon coupling
- Model accurately describes high-temperature spin processes

## Abstract

To understand emergent magnetic monopole dynamics in the spin ices Ho$_2$Ti$_2$O$_7$ and Dy$_2$Ti$_2$O$_7$, it is necessary to investigate the mechanisms by which spins flip in these materials. Presently there are thought to be two processes: quantum tunneling at low and intermediate temperatures and thermally activated at high temperatures. We identify possible couplings between crystal field and optical phonon excitations and construct a strictly constrained model of phonon-mediated spin flipping that quantitatively describes the high-temperature processes in both compounds, as measured by quasielastic neutron scattering. We support the model with direct experimental evidence of the coupling between crystal field states and optical phonons in Ho$_2$Ti$_2$O$_7$.