초전도 Sr2VO3FeAs에서 상관효과

Abstract

In the superconducting Sr2VO3FeAs, containing bimetallic layers, with maximum Tc≈ 46 K correlation effects on V ions have been investigated using LDA+U method. Within the local density approximation (LDA) this system has the one-third filled t2g manifold of V,decomposed into dxy of bandwidth W=2 eV and nearly degenerate dzxdyz of W=1 eV. Consideration of correlation effects leads to a metal-insulator transition on V ions t [수식] →d[수식] d[수식] at the critical on-site Coulomb repulsion Uc= 3.5 eV. At U=4 eV, the electronic structure, in which V ions are insulating, leads to several van Hove singularities near EF and similar Fermiology with other pnictides. Applying U to V ions results in increasing Fe moment as well as V moment, indicating somewhat hybridization between Fe and V ions even though this system is strongly 2-dimesional. Our results show possible importance of correlation effects on this system.