Spontaneous generation of the electrical voltage in charge-ordered manganite Pr0.6Ca0.4MnO3

Spontaneous generation of the electrical voltage in a Pr0.6Ca0.4MnO3 single crystal has been found. The charge and orbital ordering in the crystal takes place at T (CO) = 240 K, while the antiferromagnetic ordering occurs at T (N) = 174 K. As the temperature lowers, spontaneous voltage U increases initially slowly (in the temperature range from 300 K to T (CO)) and then more rapidly (in the range T (CO)-T (N) ). Starting from T (N) , the voltage U increases exponentially and, at 85 K, reaches 115 mV (in the ab plane) and 6.5 mV (along the c axis). The magnetic field differently affects the voltage U in different temperature ranges: it decreases the value of U in the temperature range of 85-130 K and increases in the range of 130-240 K. It is assumed that the spontaneous voltage is associated with the existence of ferromagnetic and charge orbital ordered clusters of different topologies in the crystal.