Recently, the iridate double perovskite Sr2YIrO6 has attracted considerable attention due to the report of unexpected magnetism in this Ir5+ (5d4) material, in which according to the Jeff model, a non-magnetic ground state is expected. However, in recent works on polycrystalline samples of the series Ba2−xSrxYIrO6 no indication of magnetic transitions have been found. We present a structural, magnetic and thermodynamic characterization of Sr2YIrO6 single crystals, with emphasis on the temperature and magnetic field dependence of the specific heat. Here, we demonstrate the clue role of single crystal X-ray diffraction on the structural characterization of the Sr2YIrO6 double perovskite crystals by reporting the detection of a 2a×2a×1c supercell, where a, b and c are the unit cell dimensions of the reported monoclinic subcell. In agreement with the expected non-magnetic ground state of Ir5+ (5d4) in Sr2YIrO6, no magnetic transition is observed down to 430~mK. Moreover, our results suggest that the low temperature anomaly observed in the specific heat is not related to the onset of long-range magnetic order. Instead, it is identified as a Schottky anomaly caused by paramagnetic impurities present in the sample, of the order of n∼0.5(2) \%. These impurities lead to non-negligible spin correlations, which nonetheless, are not associated with long-range magnetic ordering.
@article{arxiv.1606.05104,
title = {The iridium double perovskite Sr2YIrO6 revisited: A combined structural and specific heat study},
author = {L. T. Corredor and G. Aslan-Cansever and M. Sturza and Kaustuv Manna and A. Maljuk and S. Gass and A. Zimmermann and T. Dey and C. G. F. Blum and M. Geyer and A. U. B. Wolter and S. Wurmehl and B. Buechner},
journal= {arXiv preprint arXiv:1606.05104},
year = {2017}
}