Role of spin-orbit coupling and electron correlation in the electronic structure of a 5d pyrochlore, Y2Ir2O7

Spin-orbit coupling in 5d transition metal oxides such as It oxides is expected to be strong due to large atomic number of Ir and electron correlation strength will be weak due to large radial extension of the 5d orbitals. Hence, various anomalous electronic properties often observed in these systems are attributed to large spin-orbit interaction strength. Employing first principles approaches, we studied the electronic structure of Y2Ir2O7, which is insulating and exhibits ferromagnetic phase below 150 K. The calculated results reveal breakdown of both the above paradigms. The role of spin-orbit interaction is found to be marginal in determining the insulating ground state of Y2Ir2O7. A large electron correlation strength is required to derive the experimental bulk spectrum. (C) 2009 Elsevier Ltd. All rights reserved.