Superconductivity in multi-orbital t-J1-J2 model and its implications for iron pnictides
Department of Physics and Astronomy, Rice University - Houston, TX 77005, USA
Accepted: 31 July 2010
Motivated by the bad metal behavior of the iron pnictides, we study a multi-orbital t-J1-J2 model and investigate possible singlet superconducting pairings. Magnetic frustration by itself leads to a large degeneracy in the pairing states. The kinetic energy breaks this into a quasi-degeneracy among a reduced set of pairing states. For small electron and hole Fermi pockets, an A1g state dominates over the phase diagram but a B1g state has close-by energy. In addition to the nodeless A1g sx2y2 channel, the nodal A1g sx2+y2 and B1g dx2- y2 channels are also competitive in the magnetically frustrated J1∼J2 parameter regime. An A1g+iB1g state, which breaks time-reversal symmetry, occurs at low temperatures in part of the phase diagram. Implications for the experiments in the iron pnictides are discussed.
PACS: 74.70.Xa – Pnictides and chalcogenides / 74.20.Mn – Nonconventional mechanisms / 74.20.-z – Theories and models of superconducting state
© EPLA, 2010