ESR Study of the Phase Transitions in {N(CH₃)₄}₂CoCl₄

Abstract

ESR spectra of Mn 2+ doped in {N(CH 3 ) 4 } 2 CoCl 4 crystal were observed in the phases I, II, III, IV and V. From the temperature dependence of the spectra around three crystallographic axes, it was concluded that the incommensurable modulation wave rotated the CoCl 4 tetrahedra around the c -axis in the incommensurate phase. The amplitude of the modulation wave has the temperature dependence of Δ ϕ∝( T I - T ) 0.35 from 11°C to 21°C. The rotation angles of CoCl 4 tetrahedra around the c -axis were determined in the commensurate phase.