Observations of bistability effects in electron paramagnetic resonance experiments

Abstract

Bistability effects have been observed in electron paramagnetic resonance spectroscopy. When the sample amounts are varied, different instability regimes are detected. The homogeneous profile of the cavity resonator assumes a characteristic double-well pattern when a proper number of paramagnetic centers is put inside the cavity under magnetic resonance conditions. Saturation is not a requirement for the observation of the effect. Hysteresis loops arise from concurrence of this cavity profile and feedback effects of the spectrometer circuitry. Numerical calculations account well for the observed phenomena.