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In this talk, I will illustrate through two examples how electronic and structural couplings at oxide interfaces can lead to exciting novel properties and 2D systems [1,2].

A striking example is the interface between LaAlO3 and SrTiO3, two good band insulators, which was found to be conducting [3], and, in some doping range, superconducting with a maximum critical temperature of about 300 mK [4]. In this system, the thickness of the conducting layer is found to be a few nanometers at low temperatures. This electron liquid with low electronic density, typically 5 1013 electrons/cm2, and naturally sandwiched between two insulators is ideal for performing electric field effect experiments allowing the carrier density to be tuned and superconductivity to be switched on and off  [5,6].

I will then discuss how a coupling of instabilities can be used to design artificial ferroelectric materials with a focus on vanadate-based structures [7,8]. In these structures, it was found that the competition between the strain state and the coupling of oxygen octahedra rotations leads to an interesting “transition layer” and a reorientation of the orthorhombic long axis. This transition layer may be a way to design a functional 2D interface.

You can download the slides here.

Please register at this doodle if you want to join for the pizza.

[1] J. Mannhart and D. Schlom, Science 327, 1607 (2010).
[2] P. Zubko, S. Gariglio, M. Gabay, P. Ghosez, and J.-M. Triscone, Annual Review : Condensed Matter Physics 2, 141 (2011).
[3] A. Ohtomo, H. Y. Hwang, Nature 427, 423 (2004).
[4] N. Reyren, S. Thiel, A. D. Caviglia, L. Fitting Kourkoutis, G. Hammerl, C. Richter, C. W. Schneider, T. Kopp, A.-S. Ruetschi, D. Jaccard, M. Gabay, D. A. Muller, J.-M. Triscone and J. Mannhart, Science 317, 1196 (2007).
[5] A. Caviglia, S. Gariglio, N. Reyren, D. Jaccard, T. Schneider, M. Gabay, S. Thiel, G. Hammerl, J. Mannhart, and J.-M. Triscone, Nature 456, 624 (2008).
[6] S. Gariglio, M. Gabay, and J.-M. Triscone, Research Update, APL Materials 4, 060701 (2016).
[7] See, for instance, J. M. Rondinelli and C. J. Fennie, Adv. Mater. 24, 1961 (2012)
[8] H. Meley et al. APL Materials 6, 046102 (2018)

Location: Stuckelberg, Ecole de Physique
Time: Friday 9 June 2023, 12:10 for pizza, 12:30 start discussion