QFS2016 Book of Abstracts

Abstracts

P1.4 Quantum criticality in Kondo quantum dot coupled to helical edge states of interacting 2D topological insulators Chung Chung-Hou(1,2), Silotri Salman(1) 1) Department of Electrophysics, National Chiao-Tung University, HsinChu, Taiwan, 300, R.O.C. 2) National Center for Theoretical Sciences, HsinChu, Taiwan 300, R.O.C. We theoretically realize a novel quantum phase transition (QPT) between the one-channel Kondo (1CK) and two-channel Kondo (2CK) fixed points in a quantum dot coupled to helical edge states of interacting 2D topological insulators, recently realized experimentally in InAs/GaSb bilayer. Combining perturative renormalization group with bosonization techniques, we extract critical properties of this quantum critical point (QCP). Our work offers the first example of theoretically accessible 1CK-2CK QCP in soild state systems, and sheds light on this long standing problem since 1990s’ in Kondo dot embedded in conventional Luttinger wire due to its strong coupling nature.(NJP, 2015) P1.5 Condensation energy as a function of doping for underdoped YBa 2 Cu 3 O 6+ x cuprates Salas P., Sol´ıs M. A., Fortes M. Instituto de F´ısica, Universidad Nacional Aut´onoma de M´exico Apdo. Postal 20-364, M´exico 1000 D. F. MEXICO We report the condensation energy, the critical thermodynamic magnetic field and the mass anisotropy for superconducting cuprates YBa 2 Cu 3 O 6+ x , with x ranging from underdoping ( x = 0 . 55) to optimally doped ( x = 0 . 9). We apply the Layered Boson-Fermion model of superconductivity [1], to model layered superconductors such as cuprates. By minimizing the Helmholtz free energy of the system, two optimal parameters of the model are determined, which are the impenetrability of the planes and the paired fermion fraction. The obtained results reproduce the experimental results within a 10 % error range. [1] P. Salas, M. Fortes, M. A. Sol´ıs and F. J. Sevilla, Physica C 524 37 (2016). We would like to thank support from grants CONACyT 221030 and DGAPA-PAPIIT IN107616.

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