Observation of magnetic ordering in La 2CuO 4 by muon spin rotation spectroscopy

Abstract

Positive muon spin rotation (μSR) experiments were performed on a polycrystalline sample of La 2CuO 4 in zero applied magnetic field. Below 250 K a clear μSR frequency is observed which unambiguously demonstrates magnetic ordering in this sample. The temperature dependence of the frequency shows a continuous decrease with increasing temperature and a sharp drop to zero at 250 K. In the same temperature range the depolarization rate increases continuously and rises strongly close to the transition temperature. The extrapolated frequency at T = 0 K is 5.6 MHz which corresponds to a local magnetic field of 41 mT.