ELECTRONIC STRUCTURE OF DOUBLE PEROVSKITES A2FeReO6 (A = Ba, Ca) REVISITED.

J. I. MELO; R. WEHT

Zacatecas, Mexico

Congreso; PASI2007 - Pan American Advanced Study Institute 2007. Electronic States and Excitations on Nanostructures; 2007

National Science Foundation with a Pan American School Institute Award

Double Perovskites with A2BB’O6 formula have been of recent interest because of their peculiar magnetic and electronic properties. When going through A = Ba to Ca the system shows a metal-insulator transition (MIT) (at T=0), coincidently to a structural transition, even though conduction band filling are not significantly changed.  In this work we concentrate our attention on the A = Ba and Ca systems. Ba2FeReO6 has been proposed to be half metallic with high magnetic transition temperatures and spin dependent transport properties, while Ca2FeReO6 shows semiconductor transport behavior[1]. Our study is based on the electronic and magnetic properties of these perovskites via ab initio methods. Correlation effects are included with an approximate implementation of hybrid functionals and LDA+U scheme. We compare results for the original structure of Ba2FeReO6, Ca2FeReO6 and an averaged configuration of Ca2ReFeO6; which reproduces FeO6 and ReO6 octahedral changes. Bandstrucutre calculations are included to show the importance of correlation effects to describe MIT.