THERMODYNAMIC PROPERTIES OF PEROVSKITE ARUO(3) (A=CA, SR, AND BA) SINGLE-CRYSTALS

Magnetic susceptibility, transport properties (including magnetoresist ivity and the Hall effect), and specific heat of perovskite ARuO(3) (A =Ca, Sr, and Ba) single crystals were measured. These compounds, parti cularly CaRuO3 (paramagnetic conductor) and SrRuO3 (ferromagnetic cond uctor) are believed to have a narrow pi band and their thermodynamic properties depend in an extremely sensitive way on the degree of the b and filling and band width. This study reveals that the pi bandwidth of these compounds is largely determined by the ionic radii of the alk aline-earth A cations, i.e., the interaction between A s and O 2p orbi tals and the electron correlation becomes progressively stronger in th e series BaRuO3, SrRuO3, and CaRuO3. (C) 1997 American Institute of Ph ysics.