Observation of depolarization peak at 34 GHz accompanying the charge ordering transition in Pr0.5Ca0.5MnO3−

Abstract Electromagnetic response of Pr 0.5 Ca 0.5 MnO 3− δ at 34 GHz was measured by a cavity perturbation method. When the sample is placed at the magnetic field maximum H max of TE 011 mode, the full-width at half-maximum (FWHM) of the Q -curves and the resonant frequency conforms to the prediction of depolarization peak at the metal–insulator phase transition. These anomalies of the microwave responses are very suggestive of the synchronicity of the charge-ordering phase transition and the metal–insulator phase transition in Pr 0.5 Ca 0.5 MnO 3− δ .