Theoretical study of novel Jeff=1/2 insulator and possible superconductivity in Sr2IrO4
| Recently, the 5d transition metal oxide Sr2IrO4 has attracted much attention. In this material, three t2g orbitals of Ir atoms are hybridized with each other by the spin-orbit coupling of 5d electrons. As a result of the quantum entanglement of spin and orbital degrees of freedom, many interesting properties are induced such as a novel Jeff=|L-S|=1/2 state. To understand these properties of this system, we study the ground state of the three-orbital Hubbard model with a spin-orbit coupling term using variational Monte Carlo method. We have found that the in-plane antiferromagnetic (AF) insulator observed experimentally is well reproduced by a Gutzwiller-Jastrow type wave function. We also study the energy gain mechanism of the insulating state and discuss whether Sr2IrO4 is a Slater or a Mott insulator. Furthermore, the possibility of superconductivity (SC) under the large spin-orbit coupling is systematically examined. We show that the dx2-y2-wave"pseudospin-singlet"SC is most favored near the AF state with electron doping. |
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