2003/06/30 by J. B. Philipp, P. Majewski, Peter Majewski +13 · 4 citations
Engineering · Materials Science · Physics and Astronomy · #Advanced Condensed Matter Physics #Multiferroics and related materials #Perovskite Materials and Applications
paper · doi:10.1103/physrevb.68.144431
openalex publication_date 2003/10/24 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
The structural, transport, magnetic, and optical properties of the double perovskite A2CrWO6 with A=Sr,Ba,Ca have been studied. By varying the alkaline earth ion on the A site, the influence of steric effects on the Curie temperature TC and the saturation magnetization has been determined. A maximum TC=458K was found for Sr2CrWO6 having an almost undistorted perovskite structure with a tolerance factor f\ensuremath≃1. For Ca2CrWO6 and Ba2CrWO6 structural changes result in a strong reduction of TC. Our study strongly suggests that for the double perovskites in general an optimum TC is achieved only for f\ensuremath≃1, that is, for an undistorted perovskite structure. Electron doping in Sr2CrWO6 by a partial substitution of Sr2+ by La3+ was found to reduce both TC and the saturation magnetization Ms. The reduction of Ms could be attributed both to band structure effects and the Cr/W antisites induced by doping. Band structure calculations for Sr2CrWO6 predict an energy gap in the spin-up band, but a finite density of states for the spin-down band. The predictions of the band structure calculation are consistent with our optical measurements. Our experimental results support the presence of a kinetic energy driven mechanism in A2CrWO6, where ferromagnetism is stabilized by a hybridization of states of the nonmagnetic W site positioned in between the high spin Cr sites.