High-Frequency Dielectric Anomaly with Charge/Orbital Ordering of Pr0.5Ca0.5MnO3-δ

Abstract

Electromagnetic response of Pr 0.5 Ca 0.5 MnO 3-δ at 34 GHz was measured by a cavity perturbation method in the temperature range from 4.2 to 270 K under the magnetic field up to 5 T. Clear anomalies in the temperature dependence of both the resonant frequency and the full width at half-maximum (FWHM) of Q -curves were observed at the charge/orbital-order phase transition of Pr 0.5 Ca 0.5 MnO 3-δ . The anomalies of the microwave losses suggest the effect of the depolarization peak due to a large variation of the resistivity with the charge ordering. The dielectric anomalies may be related to a redistribution of charges at the transition related to the orbital ordering.