Zero-field muon spin echo

Abstract

In this paper the first experiments which demonstrate the generation of the spin echo response in the absence of an external magnetic field using muons implanted in elemental boron and indium phosphide are presented. In contrast to the well-established Hahn echo, the refocusing of the muon polarization was achieved with a single non-oscillatory pulse of magnetic field of short (1 μs) duration and modest (3.7 mT) amplitude, applied along the initial muon polarization at a time τ after muons have stopped in the sample. The echo amplitude was examined as a function of pulse amplitude and of the delay τ with respect to the muon pulse. The possibility to perform experiments at low temperatures employing the standard metallic helium cryostat is demonstrated, so that, for indium phosphide, the variation of the echo signal with temperature could also be followed through the onset of diffusion.