Low temperature heat capacity of Nd_2/3Ca_1/3MnO₃and (Nd_0.9Y_0.1)2/3Ca_1/3MnO³manganites: transformation of the Schottky-like anomaly

Abstract

Effect of Y-doping on interactions in the spin system of the colossal magnetoresistance compound Nd2/3Ca1/3MnO3 has been studied by the thermal relaxation heat capacity and neutron diffraction techniques in the 2 — 30 K temperature range. In 5 K temperature region a broadened Schottky-like specific heat anomaly Csch(T) has been foDnd both in the parent Nd2/3Ca1/3MnO3 and in the doped (Nd0.9Y0.1)2/3Ca1/3MnO3 compounds. The experimental data were successfully fitted by a set of three two-level Schottky contributions, implying a broadening of the exited level in the system with randomly distributed Y ions. Replacement of 10 % Nd ions by nonmagnetic Y ions leads to the about 10 % enlargement of the splitting of the ground state doublet of Nd3+ ion.