Persistent current in 2D topological superconductors

Area of Science:

• Condensed Matter Physics
• Topological Superconductivity
• Quantum Mechanics

Background:

• Topological superconductors (TSCs) host exotic Majorana fermions at their boundaries.
• Understanding the behavior of these Majorana edge modes at junctions is crucial for potential applications.

Purpose of the Study:

• To investigate the properties of a junction between two topological superconductor boundaries.
• To analyze the dependence of fermion tunneling and persistent current on magnetic flux and tunneling amplitude.

Main Methods:

• Theoretical investigation of localized edge modes of Majorana fermions at a TSC junction.
• Analysis of fermion tunneling across the junction and its dependence on magnetic flux.
• Numerical determination of parameter regimes for different persistent current behaviors.

Main Results:

• Fermion tunneling breaks time-reversal symmetry and depends on magnetic flux.
• Two distinct regimes of Majorana fermion tunneling (strong and weak) were identified.
• Strong tunneling leads to a 2π-periodic persistent current, while weak tunneling results in a 4π-periodic current due to conserved fermion parity.

Conclusions:

• The persistent current in TSC junctions is governed by Majorana edge modes and exhibits distinct behaviors based on tunneling strength.
• The study identifies parameter regions for 2π- and 4π-periodic current harmonics, offering insights into Majorana fermion properties.