We propose extended $s$-wave altermagnets ($s\mathrm{AMs}$) as a class of magnetic states that are fully gapped, spin compensated, and feature spin-polarized bands. $s\mathrm{AMs}$ are formed through valley-exchange symmetries, which act as momentum-space translations beyond standard crystallographic spin-group classifications. Using an effective two-valley model, we demonstrate that $s\mathrm{AMs}$ exhibit isotropic spin splitting, enable spin-selective transport in tailored heterostructures, and give rise to descendant pair density wave order. From a microscopic $s\mathrm{AM}$ minimal model, we develop the guiding principles to identify $s\mathrm{AMs}$ in quantum magnets.

Close

PrevNext

View figure in article

• Magnetic order
• Magnetism
• Superconductivity
• Mean field theory
• Perturbation theory