Spin and pair density waves in 2D altermagnetic metals

03.12.2025 13:00 – 15:00

Altermagnetism features collinear compensated magnetism with unconventional d-, g-, or i-wave spin order. We show that in a metallic 2D d-wave altermagnet with combined two-fold spin and four-fold lattice rotational symmetry [C2||C4], secondary instabilities can arise. Using an unbiased functional renormalization group approach, we analyze the weak-coupling instabilities of a 2D Hubbard model with a preexisting altermagnetic order inspired by our ab initio electronic structure calculations of realistic material candidates from V2X2O (X = Te, Se) family. We identify two distinct spin density wave (SDW) states that break the underlying altermagnetic [C2||C4] symmetry. Additionally, we find spin-fluctuation-induced instabilities leading to a singlet d-wave superconducting state and an unconventional commensurate pair density wave (PDW) state with extended s-wave and spin-triplet symmetry. We establish a general criterion for the unusual exchange statistics for these pair density waves and characterize their excitation spectrum, which exhibits Bogoliubov Fermi surfaces or nodal points depending on the gap size.

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Bâtiment: Ecole de Physique

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