Room temperature colossal microwave magnetoimpedance in micron-size powders of La_0.7Ba_0.3MnO₃ and La_0.7Sr_0.3MnO₃—A novel magnetic tape

We report measurements of microwave loss in micron-size powders of the manganites La_0.7Ba_0.3MnO₃ and La_0.7Sr_0.3MnO₃, 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.” © 1998 American Institute of Physics.