Real-space construction and classification for time-reversal symmetric crystalline superconductors in 2D interacting fermionic systems

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Hauptverfasser: Liu, Yi-Ming, Chen, Wei-Qiang, Gu, Zheng-Cheng
Format: Preprint
Veröffentlicht: 2026
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author Liu, Yi-Ming
Chen, Wei-Qiang
Gu, Zheng-Cheng
author_facet Liu, Yi-Ming
Chen, Wei-Qiang
Gu, Zheng-Cheng
contents Crystalline symmetry and time-reversal symmetry are commonly present in real superconducting materials. However, the topological classification of systems respecting these symmetries, particularly for interacting fermions, remains incomplete. In this work, we systematically classify time-reversal symmetry-protected crystalline topological superconductors in two-dimensional interacting fermionic systems using an explicit real-space construction. Among the resulting phases, we identify intrinsically interacting fermionic topological superconductors, i.e., phases that cannot be realized in either free-fermion or interacting bosonic systems. For spinless fermions with protecting symmetry group $C_4 \times Z_2^T$ or $D_4 \times Z_2^T$ (plus fermion parity), the intrinsic sector has a $Z_4$ classification. The corresponding root phases generating this $Z_4$ classification admit a transparent real-space construction in terms of decorated 1D blocks. These blocks are 1D fermionic symmetry-protected topological (FSPT) phases, realizable as double Majorana chains. We further find the corresponding $Z_4$ spinless intrinsic phases for wallpaper groups $p4$, $p4m$, and $p4g$. We also find an additional $Z_2$ intrinsically interacting phase for spinless fermions with wallpaper group $pm$, which is absent with the corresponding point-group symmetry alone. Moreover, these intrinsic phases naturally give rise to higher-order FSPT phases that support corner zero modes. Finally, we verify the crystalline equivalence principle for generic 2D interacting FSPT systems with both crystalline and internal symmetries.
format Preprint
id arxiv_https___arxiv_org_abs_2602_20560
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Real-space construction and classification for time-reversal symmetric crystalline superconductors in 2D interacting fermionic systems
Liu, Yi-Ming
Chen, Wei-Qiang
Gu, Zheng-Cheng
Strongly Correlated Electrons
Crystalline symmetry and time-reversal symmetry are commonly present in real superconducting materials. However, the topological classification of systems respecting these symmetries, particularly for interacting fermions, remains incomplete. In this work, we systematically classify time-reversal symmetry-protected crystalline topological superconductors in two-dimensional interacting fermionic systems using an explicit real-space construction. Among the resulting phases, we identify intrinsically interacting fermionic topological superconductors, i.e., phases that cannot be realized in either free-fermion or interacting bosonic systems. For spinless fermions with protecting symmetry group $C_4 \times Z_2^T$ or $D_4 \times Z_2^T$ (plus fermion parity), the intrinsic sector has a $Z_4$ classification. The corresponding root phases generating this $Z_4$ classification admit a transparent real-space construction in terms of decorated 1D blocks. These blocks are 1D fermionic symmetry-protected topological (FSPT) phases, realizable as double Majorana chains. We further find the corresponding $Z_4$ spinless intrinsic phases for wallpaper groups $p4$, $p4m$, and $p4g$. We also find an additional $Z_2$ intrinsically interacting phase for spinless fermions with wallpaper group $pm$, which is absent with the corresponding point-group symmetry alone. Moreover, these intrinsic phases naturally give rise to higher-order FSPT phases that support corner zero modes. Finally, we verify the crystalline equivalence principle for generic 2D interacting FSPT systems with both crystalline and internal symmetries.
title Real-space construction and classification for time-reversal symmetric crystalline superconductors in 2D interacting fermionic systems
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2602.20560