Influence of the A-cation size on the paramagnetic susceptibility in A2CoWO6 (A = Ca, Sr and Ba)

R.D. SÁNCHEZ; C.A.LÓPEZ; M.E. SALETA; J. CURIALE

Buenos Aires

Workshop; X-Latin American Workshop on Magnetism and Magnetic Materials and their Applications; 2013

Materia Condensada-CAC-CNEA

Antiferromagnetic A2CoBO6 double perovskites are interesting oxides to produce more complex systems as spin valves and others that use exchange bias mechanism. One of the reason is to reduce the mismatch effect with the ferromagnetic double perovskite Sr2FeMoO6, which exhibit intrinsic tunnelling-type magnetoresistance at room temperature. The antiferromagnetic A2CoWO6 (with A = Ca, Sr or Ba) family called our attention due to their crystalline structure versatility. Forexample, we prepared monoclinic Ca2CoWO6, tetragonal Sr2CoWO6 and cubic Ba2CoWO6 double perovskites. The crys-talline structures aect mainly the Co-O distances and the local  octahedral symmetry of the CoO6. Magnetic susceptibility experiments were performed as a function of magnetic eld and temperature. We found that the eective magnetic moment (ueff ) of Co2+ is partially unquenched and we also found that eff increases with the average of Co-O distances. In this contribution we describe a simple model that explain the experimental behavior of the eective magnetic moment and its relation with the crystal field [C.A. Lopez, M.E. Saleta, J.Curiale and R.D. Sanchez, Mat.Res.Bull. 47, 1158-1163 (2012)].