Reentrant charge ordering transition in the manganites as experimental evidence for a strain glass

Abstract

A reentrant charge ordering transition occurs within the $\ensuremath{\mu}\mathrm{m}$-scale phase-separated manganite ${(\mathrm{La},\mathrm{Pr})}_{5∕8}{\mathrm{Ca}}_{3∕8}\mathrm{Mn}{\mathrm{O}}_{3}$. This low-temperature state, in which charge-ordered and ferromagnetic-metallic phases coexist, accompanies spin-glass-like magnetism. Furthermore, thermal conductivity measurements reveal an irreversibility characteristic of a freezing transition in the lattice degrees of freedom, strongly suggesting the presence of inhomogeneous long-range strain. Our results point to a unique phase transition from a ``strain liquid'' to a ``strain glass'' state where phase-separated regions strongly interact via martensitic accommodation strain resulting in a cooperative freezing of the combined charge/spin/strain degrees of freedom.