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Main Authors: Zhang, Song-Bo, Hu, Lun-Hui, Neupert, Titus
Format: Preprint
Published: 2023
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Online Access:https://arxiv.org/abs/2302.13185
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author Zhang, Song-Bo
Hu, Lun-Hui
Neupert, Titus
author_facet Zhang, Song-Bo
Hu, Lun-Hui
Neupert, Titus
contents Finite-momentum Cooper pairing is an unconventional form of superconductivity that is widely believed to require finite magnetization. Altermagnetism is an emerging magnetic phase with highly anisotropic spin-splitting of specific symmetries, but zero net magnetization. Here, we study Cooper pairing in metallic altermagnets connected to conventional $s$-wave superconductors. Remarkably, we find that the Cooper pairs induced in the altermagnets acquire a finite centre-of-mass momentum, despite the \textit{zero} net magnetization in the system. This anomalous Cooper-pair momentum strongly depends on the propagation direction and exhibits unusual symmetric patterns. Furthermore, it yields several unique features: (i) highly orientation-dependent oscillations in the order parameter, (ii) controllable 0-$π$ transitions in the Josephson supercurrent, (iii) large-oblique-angle Cooper-pair transfer trajectories in junctions parallel with the direction where spin splitting vanishes, and (iv) distinct Fraunhofer patterns in junctions oriented along different directions. Finally, we discuss the implementation of our predictions in candidate materials such as RuO$_{2}$ and KRu$_{4}$O$_{8}$.
format Preprint
id arxiv_https___arxiv_org_abs_2302_13185
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Finite-momentum Cooper pairing in proximitized altermagnets
Zhang, Song-Bo
Hu, Lun-Hui
Neupert, Titus
Superconductivity
Finite-momentum Cooper pairing is an unconventional form of superconductivity that is widely believed to require finite magnetization. Altermagnetism is an emerging magnetic phase with highly anisotropic spin-splitting of specific symmetries, but zero net magnetization. Here, we study Cooper pairing in metallic altermagnets connected to conventional $s$-wave superconductors. Remarkably, we find that the Cooper pairs induced in the altermagnets acquire a finite centre-of-mass momentum, despite the \textit{zero} net magnetization in the system. This anomalous Cooper-pair momentum strongly depends on the propagation direction and exhibits unusual symmetric patterns. Furthermore, it yields several unique features: (i) highly orientation-dependent oscillations in the order parameter, (ii) controllable 0-$π$ transitions in the Josephson supercurrent, (iii) large-oblique-angle Cooper-pair transfer trajectories in junctions parallel with the direction where spin splitting vanishes, and (iv) distinct Fraunhofer patterns in junctions oriented along different directions. Finally, we discuss the implementation of our predictions in candidate materials such as RuO$_{2}$ and KRu$_{4}$O$_{8}$.
title Finite-momentum Cooper pairing in proximitized altermagnets
topic Superconductivity
url https://arxiv.org/abs/2302.13185