Phase transitions and magnetism in layer-structured $({\mathrm{C}}_{18}{\mathrm{H}}_{37}{\mathrm{NH}}_3{)}_2{\mathrm{MnCl}}_4$

We have studied lattice dynamics and magnetism in the perovskite-type layered structure compound $({\mathrm{C}}_{18}{\mathrm{H}}_{37}{\mathrm{NH}}_3{)}_2{\mathrm{MnCl}}_4$ by means of nuclear magnetic resonance, electron paramagnetic resonance, and superconducting quantum interference device measurements. As a result, three structural phase transitions attributed to the hydrocarbon chains and the magnetic inorganic planes, as well as the spin relaxation behaviors, were identified and characterized.