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Universal Nonequilibrium I-V Curve at an Interacting Impurity Quantum Critical Point

TKM Institutsseminar


Prof. Chung-Hou Chung


23.02.2017 12:30


Raum 10.01, Geb. 30.23, Campus Süd


National Chiao Tung University, Hsinchu


Jörg Schmalian


The nonlinear I-V curve at an interacting quantum critical point (QCP) is typically out of reach theoretically. Here, however, we provide an analytical calculation of the I-V curve at a QCP under nonequilibrium conditions and, furthermore, present experimental results to which the theory is compared. The system is a quantum dot coupled to resistive leads: a spinless resonant level interacting with an ohmic electromagnetic environment. A two channel Kondo like QCP occurs when the level is on resonance and symmetrically coupled to the leads. Though similar to a resonant level in a Luttinger liquid, a key difference enables us to obtain the current at finite temperature and bias: because there are modes that do not initially couple to the environment, an analysis in terms of weak backscattering of non-interacting fermions coupled to a modified environment is possible. Drawing on dynamical Coulomb blockade theory, we then obtain an analytical expression for the nonlinear I-V curve. The agreement between our theoretical and experimental results is remarkable.


1. G. Zhang, C.H. Chung, C.T. Ke, C.Y. Lin, H. Metrahtu, A.I. Smimov, G. Finkelstein, H. Baranger, arXiv:1609.04765

2. H. T. Mebrahtu, I. V. Borzenets, Dong E. Liu, Huaixiu Zheng, Yu. V. Bomze, A. I. Smirnov, H. U. Baranger, and G. Finkelstein, Nature 488, 61–64 (2012).

3. H. T. Mebrahtu, I. V. Borzenets, H. Zheng, Yu. V. Bomze, A. I. Smirnov, S. Florens, H. U. Baranger, and G. Finkelstein, Nat. Phys. 9, 732– 737 (2013),