Band overlap via chemical pressure control in double perovskite (Sr2−xCax)FeMoO6 (0 ⩽ x ⩽ 2.0) with TMR effect

Abstract The chemical pressure control in (Sr 2− x Ca x )FeMoO 6 (0 ⩽  x  ⩽ 2.0) with double perovskite structure has been investigated systematically. We have performed first-principles total energy and electronic structure calculations for x  = 0 and x  = 2.0. The increasing Ca content in (Sr 2− x Ca x )FeMoO 6 samples increases the magnetic moment close to the theoretical value due to reduction of Fe/Mo anti-site disorder. An increasing Ca content results in increasing (Fe 2+  + Mo 6+ )/(Fe 3+  + Mo 5+ ) band overlap rather than bandwidth changes. This is explained from simple ionic size arguments and is supported by X-ray absorption near edge structure (XANES) spectra and band structure calculations.