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

Angew Chem Int Ed Engl. 2020 Aug 3;59(32):13305-13312. doi: 10.1002/anie.202003041. Epub 2020 Jun 8.

Abstract

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-sal2 (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.

Keywords: domain wall; ferroelastic materials; manganese(III); spin crossover; structural phase transition.