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제목: Emergent Quantum Phenomena in SrTiO3 Heterostructures

연사: 김  민  우 박사님 (서울대학교)

일시: 2014년 12월 2일(화) 16:30

장소: 삼성학술정보관 7층 Creative Learning Room

초록: Oxide heterostructures have recently emerged as a new playground for exploring novel physics in low dimensional systems. Perhaps the most well known material is SrTiO3 (STO), not only as a building block of complex oxide heterostructures [1], but also as a high-mobility d0-electron semiconductor, and a superconductor with the lowest known carrier density. Using thin-film growth techniques, we have fabricated “delta-doped” STO structures that confine the superconducting Cooper pairs in 2D without surface or interface scattering. Crucially, these samples simultaneously show quantum oscillations that demonstrate the presence of 2D electron states [2]. More recently, we have found unconventional spin properties in these samples, revealed by the robustness of the superconductivity to parallel magnetic fields [3]. Furthermore, by increasing the mobility, we can clearly map out the transition of the electronic structure by dimensionality change from 2D to 3D, and approach the 2D clean regime where 2D metallic and superconducting phases can coexist [4]. These results provide an ideal system to investigate quantum phase transitions into a variety of ground states, and novel superconductivity in the 2D clean limit.

[1] A. Ohtomo & H. Y. Hwang, Nature 427, 423 (2006).
[2] Y. Kozuka et al., Nature 462, 487 (2009).
[3] M. Kim et al., Phys. Rev. B 86, 085121 (2012).
[4] M. Kim et al., Phys. Rev. Lett. 107, 106801 (2011).