Stress-Induced Domain Wall Motion in a Ferroelastic Mn3+ Spin Crossover Complex

摘要

Domain wall motion is detected for the first time during the transition to a ferroelastic and spin state ordered phase of a spin crossover complex. Single-crystal X-ray diffraction and resonant ultrasound spectroscopy (RUS) revealed two distinct symmetry-breaking phase transitions in the mononuclear Mn3+ compound [Mn(3,5-diBr-sal(2)(323))]BPh4, 1. The first at 250 K, involves the space group change Cc -> Pc and is thermodynamically continuous, while the second, Pc -> P1 at 85 K, is discontinuous and related to spin crossover and spin state ordering. Stress-induced domain wall mobility was interpreted on the basis of a steep increase in acoustic loss immediately below the the Pc-P1 transition