Colossal Magnetoresistance and Phonon Driven Exchange Dynamics in Eu$_5$Sn$_2$As$_6$

Luke Pritchard Cairns; Kohtaro Yamakawa; Shengzhi Zhang; Youzhe Chen; Bernard Field; Rainer Reczek; Ryan P. Day; Joel E. Moore; Marcelo Jaime; Sinead M. Griffin; Robert J. Birgeneau; James G. Analytis

arXiv · 2605.06649

Colossal Magnetoresistance and Phonon Driven Exchange Dynamics in Eu$_5$Sn$_2$As$_6$

Luke Pritchard Cairns·Kohtaro Yamakawa·Shengzhi Zhang·Youzhe Chen·Bernard Field·Rainer Reczek·Ryan P. Day·Joel E. Moore·Marcelo Jaime·Sinead M. Griffin·Robert J. Birgeneau·James G. Analytis

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Abstract

The emergence of colossal magnetoresistance in a new generation of Eu$^{2+}$-based antiferromagnets is intriguing given stark contrasts to the archetypal perovskite manganites and doped Eu-chalcogenides. In this study the thermal conductivity and magnetostriction of Eu$_5$Sn$_2$As$_6$ -- one such representative -- have been measured to better understand the role of the crystal lattice. Both properties are strongly field-dependent and mirror the magnetization, saturating once the Eu$^{2+}$ moments are polarized. The field-enhancement of the phonon-dominated thermal conductivity is interpreted through the lifting of a degeneracy of spin configurations, and the subsequent saturation due to quenched magnetostrain in high field. Comparison with spin-glass insulators suggests that this phenomenon is not a byproduct but rather the driver of electron delocalization due to the suppression of strong phonon scattering arising from exchange frustration.

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Luke Pritchard Cairns, Kohtaro Yamakawa, Shengzhi Zhang, Youzhe Chen, Bernard Field, Rainer Reczek, Ryan P. Day, Joel E. Moore, Marcelo Jaime, Sinead M. Griffin, Robert J. Birgeneau, James G. Analytis. 2026-05-07. Colossal Magnetoresistance and Phonon Driven Exchange Dynamics in Eu$_5$Sn$_2$As$_6$. https://arxiv.org/abs/2605.06649

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