Engineering subgap states in superconductors by the symmetry of altermagnetism

Fuente: arXiv
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Main Authors: Lu, Bo, Mercebach, Phillip, Burset, Pablo, Yada, Keiji, Cayao, Jorge, Tanaka, Yukio, Fukaya, Yuri
Format: Preprint
Published: 2025
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_version_ 1866913099975491584
author Lu, Bo
Mercebach, Phillip
Burset, Pablo
Yada, Keiji
Cayao, Jorge
Tanaka, Yukio
Fukaya, Yuri
author_facet Lu, Bo
Mercebach, Phillip
Burset, Pablo
Yada, Keiji
Cayao, Jorge
Tanaka, Yukio
Fukaya, Yuri
contents Combining superconducting and magnetic materials is a promising path to generate exotic interface subgap states. In this regard, altermagnetism is particularly interesting because it lifts spin degeneracy while providing tailored anisotropy of spin splittings. Here, we investigate the realization and control of subgap states by using the symmetry contrast between altermagnetic fields and unconventional pairings. When the symmetries of altermagnetism and unconventional superconductivity align, we demonstrate the emergence of bulk zero-energy flat bands as the Bogoliubov Fermi surface, giving rise to a zero-bias conductance peak. The symmetry and strength of $d$-wave altermagnets strongly affect the surface Andreev states from $d$-wave and chiral $d$- and $p$-wave superconductors. As a result, distinct types of subgap states are realized, including curved and flat bands, that can be detected by tunneling spectroscopy. Our results offer a solid route for designing and manipulating subgap states in superconducting systems, which can be useful for functionalizing superconducting devices.
format Preprint
id arxiv_https___arxiv_org_abs_2508_03364
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Engineering subgap states in superconductors by the symmetry of altermagnetism
Lu, Bo
Mercebach, Phillip
Burset, Pablo
Yada, Keiji
Cayao, Jorge
Tanaka, Yukio
Fukaya, Yuri
Superconductivity
Mesoscale and Nanoscale Physics
Combining superconducting and magnetic materials is a promising path to generate exotic interface subgap states. In this regard, altermagnetism is particularly interesting because it lifts spin degeneracy while providing tailored anisotropy of spin splittings. Here, we investigate the realization and control of subgap states by using the symmetry contrast between altermagnetic fields and unconventional pairings. When the symmetries of altermagnetism and unconventional superconductivity align, we demonstrate the emergence of bulk zero-energy flat bands as the Bogoliubov Fermi surface, giving rise to a zero-bias conductance peak. The symmetry and strength of $d$-wave altermagnets strongly affect the surface Andreev states from $d$-wave and chiral $d$- and $p$-wave superconductors. As a result, distinct types of subgap states are realized, including curved and flat bands, that can be detected by tunneling spectroscopy. Our results offer a solid route for designing and manipulating subgap states in superconducting systems, which can be useful for functionalizing superconducting devices.
title Engineering subgap states in superconductors by the symmetry of altermagnetism
topic Superconductivity
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2508.03364