2026/07/23 by Yu-Ping Lin
#cond-mat.str-el #cond-mat.quant-gas #cond-mat.supr-con
We show that Shiba duality maps the altermagnetic principle of momentum-dependent band splitting from spin to η-pseudospin, defining η-altermagnetism (η-ALM) as a Bogoliubov-de Gennes (BdG) counterpart of ALM in pairing and charge orders. In half-filled pure Hubbard models on bipartite lattices, the duality relates repulsion-driven antiferromagnetism (AFM) to attraction-driven η-AFM with uniform singlet pairing and staggered charge-density modulation. In the BdG bands, the Shiba-dual parity-time-reversal \mathcalP\mathcalT symmetry protects a Kramers degeneracy of η-pseudospin. Anisotropic second-neighbor hopping breaks this degeneracy and generates η-ALM. Odd-parity η-ALM shows η-pseudospin splitting, whereas even-parity η-ALM has spin-η-locked splitting. Hartree-Fock-Bogoliubov computations on checkerboard and honeycomb lattices find η-ALMs with p-, d-, and f-wave splitting structures. Possible generalizations and experimental probes are discussed.