Spin-state crossover and low-temperature magnetic state in yttrium-doped Pr_0.7Ca_0.3CoO₃

The structural and magnetic properties of two mixed-valence cobaltites with a formal population of 0.30 Co⁴⁺ ions per f.u., (Pr_1−yY_y)_0.7Ca_0.3CoO₃ (y=0 and 0.15), have been studied down to very low temperatures by means of high-resolution neutron diffraction, SQUID magnetometry and heat-capacity measurements. Combining this complex experimental research with calculations from the first priciples we determined character of spin states in cobalt ions. Furthermore, the role of rare earth elemtents in phase transitions of cobaltites with perovskite structure was clarified (see image).

Anomalous contributon of specific heat documents valency shift of preseodyme under the phase transition temperature.

¹Institute of Physics, Academy of Sciences of the Czech Republic, v. v. i., Na Slovance 2, 182 21 Prague 8, Czech Republic
²Faculty of Engineering, Iwate University, 4-3-5 Ueda, Morioka 020-8551, Japan ³Neutron Scattering Science Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA