ROOM-TEMPERATURE COLOSSAL MICROWAVE MAGNETOIMPEDANCE IN MICRON-SIZE POWDERS OF LA0.7BA0.3MNO3 AND LA0.7SR0.3MNO3 - A NOVEL MAGNETIC-TAPE

We report measurements of microwave loss in micron-size powders of the manganites La0.7Ba0.3MnO3 and La0.7Sr0.3MnO3, as functions of tempera ture and magnetic field. At zero field, the loss increases rapidly as the temperature is lowered below a frequency-dependent temperature T. The more exciting observation is that at, 295 K, the loss drops by ne arly 80% in an applied field of 600 Oe. Using this effect, a magnetic tape was ''manufactured.'' (C) 1998 American Institute of Physics.