Survived <i>J</i>_eff = 3/2 state under pressure and its implication for unconventional superconductivity in GaTa₄Se₈: LDA+DMFT study

The lacunar spinel GaTa₄Se₈ is the first established example of J_eff = 3/2 Mott insulator. By applying pressure, it undergoes insulator-to-metal and superconducting transition. In order to understand the nature of this intriguing metallic phase and its possible relation to superconductivity, we performed the LDA+DMFT (local density approximation + dynamical mean-field theory) calculations as a function of pressure and with spin-orbit coupling taken into account. It is found that, even at high pressure corresponding to the metallic and superconducting phase, J_eff = 3/2 is well identified, indicating the novel nature of the superconductivity observed in this material. Possibilities of topological superconductivity and the spin-freezing superconductivity will be discussed.