Electronic transport in nanostructures, such as long molecules or 2D exfoliated flakes, often goes through a nearly degenerate set of single-particle orbitals. Here we show that in such cases a conspiracy of the narrow band and strong e-e interactions may stabilize a non-Fermi-liquid phase in the universality class of the complex Sachdev-Ye-Kitaev (SYK) model. Focusing on signatures in quantum transport, we demonstrate the existence of anomalous power laws in the temperature dependent conductance, including algebraic scaling T3/2 in the inelastic cotunneling channel, separated from the conventional Fermi liquid T2 scaling via a quantum phase transition. The relatively robust conditions under which these results are obtained indicate that the SYK non-Fermi-liquid universality class might not be as exotic as previously thought.
Bibliographical noteFunding Information:
A. A. and D. B. were funded by the Deutsche Forschungsgemeinschaft (DFG) Project No. 277101999 TRR 183 (Project No. A03). A. K. was supported by NSF Grant No. DMR-1608238.
In this Letter, we have drawn a bridge between the physics of low capacitance quantum devices and that of the SYK Hamiltonian. The observation that signatures of the SYK universality class might show in a wider class of systems rests on two principles. First, the conspiracy of interactions and chaoticity of single-particle wave functions makes the complex SYK Hamiltonian a natural contribution in the description of nanoscopic quantum systems. Second, at low energies, we then see the emergence of two soft modes, one, ϕ ( τ ) , representing soft fluctuations of the U(1) charge mode, and another, h ( τ ) , that of conformal symmetry breaking. (The sole difference between the complex SYK system and the Majorana version, featuring in connection with holography, is the presence of the former mode.) As exemplified above, the respective effects of these two modes can be largely separated in the description of physical observables. Specifically, we have seen that low temperature quantum transport is strongly influenced by the infrared physics of the reparametrization mode. At the same time, we have also seen that the observability of these effects requires relatively narrow single-particle bands. Candidate systems where the effects discussed above might become observable include complex molecules  , “artificial atoms” based on semiconductor platforms, or exfoliated 2D materials. In view of the results discussed above it, would be intriguing to search for signatures of NFL physics in such systems. A. A. and D. B. were funded by the Deutsche Forschungsgemeinschaft (DFG) Project No. 277101999 TRR 183 (Project No. A03). A. K. was supported by NSF Grant No. DMR-1608238.  1 A. Vilan , D. Aswal , and D. Cahen , Chem. Rev. 117 , 4248 ( 2017 ). CHREAY 0009-2665 10.1021/acs.chemrev.6b00595  2 L. Merces , R. F. de Oliveira , D. H. S. de Camargo , and C. C. B. Bufon , J. Phys. Chem. C 121 , 16673 ( 2017 ). JPCCCK 1932-7447 10.1021/acs.jpcc.7b02528  3 T. A. Su , M. Neupane , M. L. Steigerwald , L. Venkataraman , and C. Nuckolls , Nat. Rev. Mater. 1 , 16002 ( 2016 ). NRMADL 2058-8437 10.1038/natrevmats.2016.2  4 D. Porath , N. Lapidot , and J. Gomez-Herrero ,
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