Thermoelectric Effect in Altermagnet-Superconductor Junctions

Abstract

We propose altermagnet-superconductor junctions as a way to achieve a thermoelectric response in metals free of external or stray magnetic fields. We combine qualitative analysis in a simplified model with a more rigorous approach based on the inverse proximity effect in the functional-integral formulation. We show that coupling an altermagnet to a superconductor in a bilayer induces a momentum-dependent spin-splitting in the superconductor. When tunneling occurs between this bilayer and a different altermagnet, a spin-dependent particle-hole symmetry breakdown arises in the transport, which leads to a thermoelectric response. Our results show that the altermagnet-superconductor junctions may achieve comparable thermoelectric performance to ferromagnet-superconductor junctions, featuring a nonmonotonic dependence of the figure of merit on the strength of the altermagnetic splitting. We also point out an often overlooked fact regarding the inverse proximity effect in superconductors, namely that even in a normal metal-superconductor junction there is a minigap in the superconductor, which gives rise to a four-peak structure in the DOS reminiscent of spin-split superconductors. Our results show that altermagnetic metals, unlike conventional antiferromagnets, can be used for efficient cryogenic thermoelectricity.

arXiv comment14 pages, 11 multi-panel figures

References in corpus (33)

• Altermagnetism: spin-momentum locked phase protected by non-relativistic symmetries
• Opportunities for mesoscopics in thermometry and refrigeration: Physics and applications
• Crystal Hall effect in Collinear Antiferromagnets
• Observation of the Anomalous Hall Effect in a Collinear Antiferromagnet
• Giant momentum-dependent spin splitting in centrosymmetric low Z antiferromagnets
• Efficient Electrical Spin-Splitter Based on Non-Relativistic Collinear Antiferromagnetism
• Observation of spin splitting torque in a collinear antiferromagnet RuO2
• Broken Kramers' degeneracy in altermagnetic MnTe
• Tilted spin current generated by the collinear antiferromagnet RuO2
• Direct observation of altermagnetic band splitting in CrSb thin films
• Observation of spin-splitter torque in collinear antiferromagnetic RuO${}_2$
• Antiferromagnetism in RuO${}_2$ as $d$-wave Pomeranchuk instability
• Colloquium: Nonequilibrium effects in superconductors with a spin-splitting field
• Induced Ferromagnetism due to Superconductivity in Superconductor-Ferromagnet structures
• Nonlocal Thermoelectric Effects and Nonlocal Onsager Relations in a Three-Terminal Proximity-Coupled Superconductor-Ferromagnet Device
• Huge thermoelectric effects in ferromagnet-superconductor junctions in the presence of a spin-splitting field
• Altermagnetism with Non-collinear Spins
• Observation of thermoelectric currents in high-field superconductor-ferromagnet tunnel junctions
• Saturation of the anomalous Hall effect at high magnetic fields in altermagnetic RuO2
• Inverse proximity effect in superconductor-ferromagnet structures: From the ballistic to the diffusive limit
• Nonlinear thermoelectricity with electron-hole symmetric systems
• Spin screening of magnetic moments in superconductors
• Superconductor-altermagnet memory functionality without stray fields
• Nonlocal Thermoelectricity in a S-TI-S Junction in Contact with a N-Metal Probe: Evidence for Helical Edge States
• Very large thermophase in ferromagnetic Josephson junctions
• Thermopower induced by a supercurrent in superconductor-normal-metal structures
• Oscillations of Induced Magnetization in Superconductor-Ferromagnet Heterostructures
• Theory of a large thermoeffect in superconductors doped with magnetic impurities
• Spin caloritronics with superconductors: Enhanced thermoelectric effects, generalized Onsager response-matrix, and thermal spin currents
• Giant thermoemf in multiterminal superconductor/normal metal mesoscopic structures
• Interface-induced magnetization in altermagnets and antiferromagnets
• Inverse proximity effect in $s$-wave and $d$-wave superconductors coupled to topological insulators
• Thermoelectric signatures of order-parameter symmetries in iron-based superconducting tunnel junctions

Cited by in corpus (11)

• Minimal Models and Transport Properties of Unconventional $p$-Wave Magnets
• Superconducting phenomena in systems with unconventional magnets
• Unconventional p-wave and finite-momentum superconductivity induced by altermagnetism through the formation of Bogoliubov Fermi surface
• Impurity-induced Friedel oscillations in altermagnets and $p$-wave magnets
• Nonlinear Superconducting Magnetoelectric Effect
• Tunneling Magnetoresistance Effect in Altermagnets
• Emergence of tunable exceptional points in altermagnet-ferromagnet junctions
• Viscoelastic tensor and hydrodynamics of altermagnets
• Engineering subgap states in superconductors by the symmetry of altermagnetism
• Large Tunable Thermoelectric Effects in Superconducting Spin Valves with Commercially Available Materials
• Josephson effects in the spin-triplet superconductor/altermagnet/spin-triplet superconductor junctions: the detection of the intrinsic $\mathbf{d}$-vector