Jean-Marc Triscone, DPMC, University of Geneva

Jeudi 17 Octobre 2013, 14h
Amphi Holweck, Esc C, 1ème etage

Interfacial Effects in Novel Oxide Heterostructures

Jean-Marc Triscone
DPMC, University of Geneva, 24 quai E.-Ansermet, CH-1211 Geneva 4, Switzerland

Oxide materials display within the same family of compounds a variety of exciting electronic properties ranging from ferroelectricity to ferromagnetism and superconductivity. These systems are often characterized by strong electronic correlations, complex phase diagrams and competing ground states. This competition makes these materials very sensitive to external parameters such as pressure or magnetic field. An interface, which naturally breaks inversion symmetry, is a major perturbation and one may thus expect that electronic systems with unusual properties can be generated at oxide interfaces [1,2]. A striking example is the interface between LaAlO3 and SrTiO3, two good band insulators, which was found in 2004 to be conducting [3], and, in some doping range, superconducting with a maximum critical temperature of about 200 mK [4].
In this presentation, I will motivate the search for novel properties at oxide interfaces. I will then focus on the LaAlO3/SrTiO3 system. In this latter interfacial system, the thickness of the electron gas is found to be a few nanometers at low temperatures. This electron gas 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. I will discuss the origin of the electron gas [5] ; superconductivity [4,6] ; field effect experiments and the phase diagram of the system [6] ; the role of spin orbit [7,8] ; and the physics of high mobility samples that display Shubnikov de Haas oscillations [9].
If time allows, I will also talk about nickelate-based heterostructures that are attracting a lot of attention [10]. In such structures, charge transfer and charge ordering phenomena may induce novel properties as recently observed in (111) LaNiO3/LaMnO3 superlattices where evidences for exchange bias were found. In this particular case, it indicates that a magnetic order is induced within the paramagnetic LaNiO3 material when embedded between ferromagnetic LaMnO3 layers [11].

[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] M.L. Reinle-Schmitt, C. Cancellieri, D. Li, D. Fontaine, S. Gariglio, M. Medarde, E. Pomjakushina, C.W. Schneider, Ph. Ghosez, J.-M. Triscone, and P.R. Willmott, Nature Communications, 3, 932 (2012).
[6] 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).
[7] A.D. Caviglia, M. Gabay, S. Gariglio, N. Reyren, C. Cancellieri, and J.-M. Triscone, Physical Review 104, 126803 (2010).
[8] A. Fête, S. Gariglio, A. D. Caviglia, M. Gabay, J.-M. Triscone, Physical Review B (RC) 86, 201105 (2012).
[9] A.D. Caviglia, S. Gariglio, C. Cancellieri, B. Sacépé, A.Fête, N. Reyren, M. Gabay, A.F. Morpurgo, J.-M. Triscone, Physical Review Letters 105, 236802 (2010).
[10] J. Chaloupka, G. Khaliullin, Physical Review Letters 100, 016404 (2008).
[11] M. Gibert, P. Zubko, R. Scherwitzl, J. Iniguez, and J.-M. Triscone, Nature Materials 11, 195 (2012).

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