arXiv subjects

Leo Katayama

Publications and source records attributed to Leo Katayama.

2 recordsLinked to original sources

arXiv2025

Noise-to-current ratio divergence as a fingerprint of dispersing Majorana edge modes

The definitive detection of Majorana modes in topological superconductors is a key issue in condensed matter physics. Here we propose a smoking-gun experiment for the detection of one-dimensional dispersing Majorana edge modes, based on theoretical results for multi-terminal transport in a setup consisting of two normal metal leads and a topological superconductor. In the proposed device, the unpaired nature of the Majorana edge modes inherently leads to the absence of the charge current in the linear response regime, while the current fluctuation remains significant. Therefore, the divergence in the noise-to-current ratio serves as unambiguous evidence for the presence of the dispersing Majorana edge modes. We reach this conclusion analytically, without relying on any specific model of topological superconductors. In addition, using tight-binding models of topological-insulator-based topological superconductors, we numerically verify the predicted divergent noise-to-current ratio. We also discuss the application of our proposal to the CoSi$_2$/TiSi$_2$ heterostructure and the iron-based superconductor FeTe$_{1-x}$Se$_x$.

cond-mat.supr-con↗

arXiv2025

Majorana flat bands and anomalous proximity effects in $p$-wave magnet--superconductor hybrid systems

Flat-band Majorana bound states of nodal $p$-wave superconductors give rise to striking electromagnetic anomalies, reflecting their high degree of degeneracy at the Fermi level. However, experimental investigations of these states have been limited because of the scarcity of materials exhibiting intrinsic $p$-wave superconductivity. In this Letter, we demonstrate that Majorana flat bands can emerge in a hybrid system consisting of a conventional superconductor and a $p$-wave magnet, a recently proposed class of unconventional magnets that possess a unique composite symmetry, the $[C_{2\perp}||\boldsymbol{t}]$ symmetry. The degeneracy of the flat-band Majorana bound states is protected by chiral symmetry from the BDI symmetry class, which originates from the $[C_{2\perp}||\boldsymbol{t}]$ symmetry of the $p$-wave magnet. In addition, we predict the robust appearance of a zero-bias conductance peak in a dirty normal-metal--superconductor junction containing a $p$-wave magnet, which serves as an unambiguous signature of anomalous proximity effects associated with the Majorana flat bands.

cond-mat.supr-con↗