Speaker: Yoram Dagan (School of Physics and Astronomy, Tel Aviv University, 69978, Tel Aviv, Israel)

Time: September 13, 2017 16:00

Place: 理科楼C302报告厅

Abstract: The two dimensional electron liquid formed at the (111) interface between SrTiO₃ and LaAlO₃ is a laboratory for studying electronic properties in tunable correlated hexagonal systems. Symmetry changes imposed by the interface and by various structural transitions in the bulk can affect the electronic properties at the interface. In addition, this system can be smoothly tuned from the superconductor to the insulator regime.

The normal state properties of the (111) LaAlO₃/SrTiO₃ interface are indicative of contributions from electron-type and hole-type charge carriers. The latter are also consistent with the polar structure of this interface. Upon applying gate voltage to add electrons, a band with a higher spin state gets populated, resulting in a six-fold anisotropic magnetoresistance [1].

Superconductivity is observed in a dome-shaped region in the carrier density – temperature phase diagram. The upper critical field is strongly anisotropic and exceeds the Clogston-Chandrasekhar limit. This suggests strong spin-orbit interaction Ɛ_so. Surprisingly, Ɛ_so is also nonmonotonic as a function of gate voltage as found both from analysis of the superconducting properties and of the weak antilocalization measurements [2].

Finally, the nature of the transition from superconductor to insulator will be discussed in the framework of a quantum phase transitions in an electronically disordered two-dimensional superconducting system [3].

[1] P. K. Rout, I.Agireen, E. Maniv, M. Goldstein,Y . Dagan Physical Review B 95 (24), 241107. [2] P. K. Rout, E. Maniv,Y . Dagan, arXiv preprint arXiv:1706.01717.

[3] M. Mograbi et al., To be published.

Bio: PhD 2001 Tel Aviv University under the supervision of Guy Deutscher 2001-2005 Research Associate, University of Maryland – College Park with R. L. Greene 2005-2009 Senior Lecturer and Associate Professor, Tel Aviv University 2015-Today Professor, Tel Aviv University

Research interest: superconductivity, strongly correlated materials, oxide interfaces