Relationship between spontaneous generation of voltage and structural features in a single crystal of Pr0.6Ca0.4MnO3

Spontaneous generation of electrical voltage U was found for the perovskite-like single crystal of Pr0.6Ca0.4MnO3, wherein the charge and orbital orderings occur at TCO = 240 K and the antiferromagnetic one occurs at the Neel point TN = 174 K. With decreasing the temperature, the U value increases first slowly (in the temperature range of 300 K-TCO) and then more rapidly (TCO-TN). Starting from TN, U increases exponentially and, at 85 K, reaches the value of 115 mV (in the ab plane) and 6.5 mV (along the c axis). The magnetic field has a different effect on the U value in different temperature ranges: in the temperature range of 85–130 K, it decreases U and, in the range of 130–240 K, increases U. The spontaneous voltage is thought to be caused by the existence of ferromagnetic and charge-orbital-ordered clusters of different topology in the sample. The latter clusters have own features and their structure are described by the non-centrosymmetric space group P21nm.