Structural, Electronic, and Physical Properties of a New Layered Cr-Based Oxyarsenide Sr2Cr2AsO3

We report synthesis, crystal structure, and physical properties of Sr 2 Cr 2 AsO 3 . The new compound crystallizes in a Sr 2 GaO 3 CuS-type structure with two distinct Cr sites, Cr(1) in the perovskite-like block layers of "Sr 3 Cr 2 O 6 " and Cr(2) in the ThCr 2 Si 2 -type layers of "SrCr 2 As 2 ". An inter-block-layer charge transfer is explicitly evidenced, which dopes electrons in the CrO 2 planes and simultaneously dopes holes into the CrAs layers. Measurements of electrical resistivity, magnetization, and specific heat, in combination with density-functional theoretical calculations, indicate that the title material is an antiferromagnetic metal. The Cr(2) magnetic moments in the CrAs layers order at 420 K, while the Cr(1) spins in the CrO 2 planes show quasi-two-dimensional magnetism with long-range ordering below 80 K. Both Neel temperatures are significantly reduced, compared with those of the cousin material Sr 2 Cr 3 As 2 O 2 , probably due to the intrinsic charge-carrier doping. Complex re-entrant magnetic transitions with a huge magnetic hysteresis were observed at low temperatures.