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

A reentrant charge ordering transition occurs within the mu m-scale phase-separated manganite (La, Pr)(5/ 8)Ca3/8MnO3. 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.