Effects of the progressive substitution of La3+ by Gd3+ in the magnetic and transport properties of La2/3Ca1/3MnO3

Abstract A systematic study of the magnetic and transport properties of the system (La 1− x Gd x ) 0.67 Ca 0.33 MnO 3 (0⩽ x ⩽1) is presented in this article. Through this series, a great crystallographic distortion is achieved but keeping constant the electronic density. At low Gd 3+ content, these ions behaves in a paramagnetic state following a Brillouin function. Low-temperature ferromagnetism remains unchanged. However, for the samples with large Gd 3+ content a complex magnetic behavior arises from several competing interaction as super-exchange, double-exchange and also the interaction between Gd and Mn ions. Resistivity and thermopower follow a progressive increase as Gd 3+ content does, but the polaron energy in the paramagnetic range remains independent of all these changes. Thermopower infinite value is also determined and analyzed.