Abstract
AbstractDomain 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
Highlights
Domain walls (DWs) in ferroic materials—ferromagnets, ferroelectrics, ferroelastics—represent the regions where there is a change in order parameter.[1]
[Mn(3,5-diBr-sal2(323))]BPh4, 1, belongs to the [Mn(Rsal2(323))]+ series of Schiff base complexes, many of which exhibit thermal spin crossover (SCO) or stabilization of the rare S = 1 state.[14f,17] Dark red crystals of complex 1 were prepared in a one-pot synthesis, Scheme 1, and magnetic susceptibility in heating and cooling modes over the temperature range 4– 300 K was recorded on a SQUID magnetometer in an applied field of 0.1 T, Figure 1 a and Figure S1
A 9.3 % increase in cM T was observed on cooling from 300 K (2.49 cm3 molÀ1 K) to 95 K (2.72 cm3 molÀ1 K), whereupon an abrupt drop to a cM T value of 2.1 cm3 molÀ1 K was observed with a T1=2fl value of 82 K, Figure S2
Summary
Domain walls (DWs) in ferroic materials—ferromagnets, ferroelectrics, ferroelastics—represent the regions where there is a change in order parameter.[1]. Felton Centre for Nanostructured Media, School of Mathematics and Physics, Queen’s University of Belfast, Belfast, BT7 1NN, Northern Ireland (UK)
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