Giant anisotropic magnetoresistance in oxygen-vacancy-ordered epitaxial La 0.5 Sr 0.5 Co O 3 − δ films

Anisotropic Magnetoresistance (AMR) is a property of all conductive ferromagnets, where the electrical resistivity depends on the relative orientation of the current and magnetization. In this work it is shown that the perovskite cobaltite La1-xSrxCoO3-d displays a giant form of AMR in epitaxial thin films, 20 times enhanced over bulk, and 10-100 times typical transition metals. The effect is ascribed to symmetry lowering due to spatial ordering of oxygen vacancies, pointing to a new route to enhance properties of complex oxides. The AMR values (up to 40%) are among the largest reported in the 160-year history of the effect.