Giant broadening of EPR linewidth near the incommensurate phase transitions of (N(CH3)4)2CuCl4

Abstract The width of the electron spin resonance line of Cu 2+ has been found anomalously large in the incommensurate phase of tetramethylammonium tetrachlorocuprate. Upon cooling, the decrease of the EPR linewidth with temperature changes of regime with a power-law exponent which decreases from 10 near T c = 293 K down to 1 at 110 K. The power-law exponent also decreases upon heating.