Ramesh Budhani (IIT Kanpur): Quantum Phases and Phase Transitions in Two-Dimentional Highly Correlated Metals at Oxide Interfaces

The two-dimensional diffusive metal stabilized at the interface of SrTiO3 and the Mott Insulator perovskite LaTiO3[1-2] has challenged many notions related to the formation and electronic behavior of the two-dimensional electron gas (2DEG) at the well studies LaAlO3-SrTiO3 interface. Here we discuss specifically the stability of the superconducting phase[3] at LaTiO3 – SrTiO3 interface, the nature of the superconductor – normal metal quantum phase transition (T=0 limit) driven by magnetic field, significance of the field vis-à-vis the Chandrasekhar - Clogston limit for depairing, and how the transition is initiated when the extent of Coulomb interaction amongst charge carriers is modulated by electrostatic gating[4]. The nature of the superconducting condensate is highlighted in the light of the Ti - t2g orbital driven bands and their filling in the presence of a strong Rashba spin – orbit interaction (SOI). Towards the end of the talk, we will discuss the prominent effects of Rashba SOI on normal state quantum transport and how it renormalizes a Kondo-like electronic behavior in range of temperature Tc< T < 5K[5-7]. The prominence of the Ti 3d0 and Ti 3d1 correlated electron physics in these systems will be demonstrated further from our recent studies of 2DEG in ion irradiated SrTiO3 crystals[8,9].
1. Advanced Materials 22, 4448(2010). 2. Phys. Rev. B 86, 075127(2012).
3. Nature Communications, 1, 89(2010). 4. Nature Materials 12, 542(2013).
5. Phys. Rev. B (Rapid Communication) 90, 081107(2014). 6. Phys. Rev. B 90, 075133(2014). 7. Phys. Rev. B 94, 115165 (2016).
8. Phys. Rev. B 91, 205117(2015). 9. Phys. Rev. B 92, 235115 (2015).