What it is
Researchers show that magnetic quantum oscillation measurements provide a high-resolution, bulk-sensitive, 3D mapping of the order parameter in the unconventional magnet CrSb. Rotating a magnetic field through high- and low-symmetry directions of the CrSb Brillouin zone reveals that the altermagnetic band structure reduces the symmetry of each spin-split Fermi sheet away from nodal orientations. In momentum space, the exchange splitting between up- and down-spins follows the profile of the yz(3x²-y²) real spherical harmonic, the pattern of a hydrogen g-orbital. The work establishes CrSb as a prototypical g-wave metallic altermagnet.
Why it matters
Order parameter symmetry is notoriously difficult to resolve in unconventional superconductors, leaving the analogous symmetry of altermagnets, in which up- and down-spin species have non-degenerate Fermi surfaces, hard to measure directly. Quantum oscillatory quasiparticle spectroscopy provides a bulk-sensitive probe that maps this symmetry across the 3D Brillouin zone.
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Filed underaltermagnetism, quantum oscillations, CrSb, condensed matter, order parameter