Conductance fingerprint of Majorana fermions in the topological Kondo effect

Research output: Contribution to journalArticlepeer-review

Authors

  • Martin R. Galpin
  • Andrew K. Mitchell
  • Jesada Temaismithi
  • David E. Logan
  • Nigel R. Cooper

Colleges, School and Institutes

External organisations

  • University of Cambridge

Abstract

We consider an interacting nanowire/superconductor heterostructure attached to metallic leads. The device is described by an unusual low-energy model involving spin-1 conduction electrons coupled to a nonlocal spin-12 Kondo impurity built from Majorana fermions. The topological origin of the resulting Kondo effect is manifest in distinctive non-Fermi-liquid (NFL) behavior, and the existence of Majorana fermions in the device is demonstrated unambiguously by distinctive conductance line shapes. We study the physics of the model in detail, using the numerical renormalization group, perturbative scaling, and Abelian bosonization. In particular, we calculate the full scaling curves for the differential conductance in ac and dc fields, onto which experimental data should collapse. Scattering t matrices and thermodynamic quantities are also calculated, recovering asymptotes from conformal field theory. We show that the NFL physics is robust to asymmetric Majorana-lead couplings, and here we uncover a duality between strong and weak coupling. The NFL behavior is understood physically in terms of competing Kondo effects. The resulting frustration is relieved by inter-Majorana coupling which generates a second crossover to a regular Fermi liquid.

Details

Original languageEnglish
Article number045143
Number of pages15
JournalPhysical Review B
Volume89
Issue number4-15
Publication statusPublished - 31 Jan 2014

Keywords

  • 71.10.Hf, 72.10.Fk, 73.21.La, 74.78.Na