Thermoelectric detection of Andreev states in unconventional superconductors

Tony Savander*, Shun Tamura, Christian Flindt, Yukio Tanaka, Pablo Burset

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

We theoretically describe a thermoelectric effect that is entirely due to Andreev processes involving the formation of Cooper pairs through the coupling of electrons and holes. The Andreev thermoelectric effect can occur in ballistic ferromagnet-superconductor junctions with a dominant superconducting proximity effect on the ferromagnet, and it is very sensitive to surface states emerging in unconventional superconductors. We consider hybrid junctions in two and three dimensions to demonstrate that the thermoelectric current is always reversed in the presence of low-energy Andreev bound states at the superconductor surface. A microscopic analysis of the proximity-induced pairing reveals that the thermoelectric effect only arises if even- and odd-frequency Cooper pairs coexist in mixed singlet and triplet states. Our results are an example of the richness of emergent phenomena in systems that combine magnetism and superconductivity, and they open a pathway for exploring exotic surface states in unconventional superconductors.

Original languageEnglish
Article number043388
Number of pages17
JournalPHYSICAL REVIEW RESEARCH
Volume2
Issue number4
DOIs
Publication statusPublished - 18 Dec 2020
MoE publication typeA1 Journal article-refereed

Keywords

  • TUNNELING SPECTROSCOPY
  • PAIRING SYMMETRY
  • QUASI-PARTICLES
  • SURFACE-STATES
  • BOUND-STATES
  • SPIN
  • SUPERCURRENTS
  • IMBALANCE

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