  We investigated temperature and magnetic field dependent radio-frequency
electromagnetic absorption in La0.67Ba0.33MnO3 by monitoring changes in
resonance frequency (fr) and current (II) through a LC resonant circuit powered
by an integrated chip oscillator. The ferromagnetic to paramagnetic transition
at Tc in zero external magnetic field is accompanied by an abrupt increase in
fr and I and they are tunable by small external magnetic field. We observed
fractional changes as much as 46% in delfr/fr and 23% in delI/I around Tc under
H = 0.1 T that can be exploited for low magnetic field sensors and other
applications.
