Nonlinear dynamics of a magnetization subject to RF feedback field: new experimental evidence

Abstract In a recent study, the dynamics of large magnetization subject to a RF feedback field from the detection circuit of the probe was investigated both theoretically and experimentally. A simple model including non-linear modification of the Bloch equations allowed us to predict the occurrence of repeated bursts of NMR transverse magnetization during evolution (named self-sustained maser pulses). However, the decay of the amplitude of these repeated maser pulses with a characteristic time 4 T 1 predicted by this simple model could not be observed and the experiments showed a regime of non-attenuated self-sustained maser pulses. This was interpreted as a direct consequence of B 0 inhomogeneities. In this paper we present new experimental evidence that support this assumption and that further demonstrate the role of B 0 inhomogeneity. To cite this article : A. Louis-Joseph et al., C. R. Chimie 7 (2004).