Conductance fingerprint of Majorana fermions in the topological Kondo effect
Abstract
We consider an interacting nanowire/superconductor heterostructure attached to metallic leads. The device is described by an unusual lowenergy model involving spin1 conduction electrons coupled to a nonlocal spin1/2 Kondo impurity built from Majorana fermions. The topological origin of the resulting Kondo effect is manifest in distinctive nonFermiliquid (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 Majoranalead 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 interMajorana coupling which generates a second crossover to a regular Fermi liquid.
 Publication:

Physical Review B
 Pub Date:
 January 2014
 DOI:
 10.1103/PhysRevB.89.045143
 arXiv:
 arXiv:1312.5971
 Bibcode:
 2014PhRvB..89d5143G
 Keywords:

 71.10.Hf;
 73.21.La;
 74.78.Na;
 72.10.Fk;
 NonFermiliquid ground states electron phase diagrams and phase transitions in model systems;
 Quantum dots;
 Mesoscopic and nanoscale systems;
 Scattering by point defects dislocations surfaces and other imperfections;
 Condensed Matter  Strongly Correlated Electrons;
 Condensed Matter  Mesoscale and Nanoscale Physics
 EPrint:
 17 pages, 8 figures