2 00 4 Giant magnetic - field changes in radio - frequency absorption in La 0 . 67 Sr 0 . 33 MnO 3 near the Curie temperature

The DC transport properties of and the radio-frequency (RF) wave absorption (at 2.525 MHz) in a sample of La0.67Sr0.33MnO3 prepared by floating-zone method are measured. The Curie temperature, Tc, of the sample is about 374 K. Giant temperature and magnetic-field variations in RF absorption are found in the vicinity of Tc. Relative change of the RF absorption in magnetic field (magnetoabsorption) is about 67% in field 2.1 kOe and about 55% in field 1 kOe. This giant magnetoabsorption effect can be used to develop RF devices controlled by temperature and low magnetic field. A weak temperature dependence of magnetoabsorption for the sample studied in the range from room temperature to about 350 K makes it especially attractive for practical use. The RF study supplemented with transport, magnetoresistive and magnetic measurements enables us to discuss the optimal properties of manganite samples for observation of giant magnetoabsorption in low field.