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 temperature 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 nearly 80% in an applied field of 600 Oe. Using this effect, a magnetic tape was “manufactured.”