Thermal and Magnetic Field Switching in a Two‐Step Hysteretic Mn<sup>III</sup> Spin Crossover Compound Coupled to Symmetry Breakings
Emiel Dobbelaar, Vibe B. Jakobsen, Elżbieta Trzop, Minseong Lee, Shalinee Chikara, X. X. Ding, Helge Müller‐Bunz, Kane Esien, Solveig Felton, Michael A. Carpenter, Éric Collet, Grace G. Morgan, Vivien S. Zapf
Abstract
Abstract A Mn III spin crossover complex with atypical two‐step hysteretic thermal switching at 74 K and 84 K shows rich structural–magnetic interplay and magnetic‐field‐induced spin state switching below 14 T with an onset below 5 T. The spin states, structures, and the nature of the phase transitions are elucidated via X‐ray and magnetization measurements. An unusual intermediate phase containing four individual sites, where are in a pure low spin state, is observed. The splitting of equivalent sites in the high temperature phase into four inequivalent sites is due to a structural reorganization involving a primary and a secondary symmetry‐breaking order parameter that induces a crystal system change from orthorhombic→monoclinic and a cell doubling. Further cooling leads to a reconstructive phase transition and a monoclinic low‐temperature phase with two inequivalent low‐spin sites. The coupling between the order parameters is identified in the framework of Landau theory.