Microwave power absorption as a function of temperature and magnetic field in the ferroelectromagnet [formula omitted

Abstract

We report on the effects of temperature and DC magnetic field on microwave power absorption measurements at 8.8–9.8 GHz, in powder samples of the ferroelectromagnet Pb ( Fe 1 / 2 Nb 1 / 2 ) O 3 (PFN). Two techniques recently implemented are used: magnetically modulated microwave absorption spectroscopy (MAMMAS) and low-field microwave absorption spectroscopy (LFMAS), the measurements were performed in the 77–520 K temperature range. The MAMMAS technique allows the detection of the para-antiferromagnetic and ferro-paraelectric transitions at T N 1 ∼ 144.1 K and T min ∼ 398.1 K , respectively. The profiles obtained by plotting the slope vs. temperature of the LFMAS line, while cooling or heating, are similar to those detected by the MAMMAS technique, giving evidence that both types of measurement are due to the same processes of absorption, by paramagnetic dipoles at all temperatures. We conclude that both measurements are a manifestation of the same response to electromagnetic absorption, in which the same physical processes take place.