HiSORセミナー（物性セミナー合同）
Novel two-dimensional electron systems at the surface of transition-metal oxides
日時 2017年7月25日 （火） 16:20 - 17:50
場所 理学研究科 C212
講師 Andrés F. Santander-Syro
(CSNSM, Université Paris-Sud / Hiroshima Synchrotron Radiation Center (HSRC), Hiroshima University)
Transition-metal oxides (TMOs) show remarkable properties, not found in standard semiconductors, such as high-temperature superconductivity or metal-to-insulator transitions. The realization of two-dimensional electron gases (2DEGs) in TMOs is crucial for harnessing the functionalities of these materials for future applications. Additionally, such 2DEGs offer the possibility to explore new physics emerging from the combined effects of electron correlations and low-dimensional confinement.
In this talk, I will first introduce our discovery that 2DEGs can be simply realized at the surface of various insulating TMOs, such as the quantum paraelectric SrTiO3 [1], the strong spin-orbit coupled KTaO3 [2], or the photo-catalyst TiO2 [3]. Then, I will show how the choice of the surface termination allows tailoring the electronic structure and symmetries of these 2DEGs [4-5], paving the way for the quest of topological states in correlated oxides. Furthermore, I will discuss our studies of magnetism in the 2DEG at the surface of oxygen-deficient SrTiO3 [6]. Finally, I will describe our recent development of a simple universal method to fabricate these 2DEGs in several other oxides, such as the ferroelectric BaTiO3, which allows measuring its transport characteristics –and is thus promising for the realization of oxide devices [7].
[1] A. F. Santander-Syro et al., Nature 469, 189 (2011).
[2] A. F. Santander-Syro et al., Phys. Rev. B 86, 121107(R) (2012).
[3] T. C. Rödel et al., Phys. Rev. B 92, 041106(R) (2015).
[4] C. Bareille et al., Sci. Rep. 4, 3586 (2014).
[5] T. C. Rödel et al., Phys. Rev. Applied 1, 051002 (2014).
[6] T. Taniuchi et al., Nat. Commun. doi: 10.1038/NCOMMS11781 (2016).
[7] T. C. Rödel et al., Adv. Mater. doi:10.1002/adma.201505021 (2016).
問合せ先 奥田太一 (放射光科学研究センター)
