Topological superconductivity requires breaking time-reversal symmetry — typically accomplished by applying an external magnetic field. But external fields destroy superconductivity by pair-breaking. The Zeeman splitting needed for topological physics and the pair-breaking that kills superconductivity are the same mechanism, creating a narrow window that's hard to hit experimentally.
Odd-parity magnets offer an escape. These materials have magnetic order that breaks time-reversal symmetry but does so in a hidden way: the Zeeman field isn't visible in the uniform magnetization but appears in the band structure as a non-relativistic spin splitting. The splitting arises from an emergent gauge field — a spin loop current that acts like a magnetic field for electrons but doesn't produce a net magnetization that would destroy superconductivity.
The magnitude is the surprise: hundreds of meV. This is orders of magnitude larger than typical spin-orbit-induced splittings and large enough that conventional s-wave superconductivity (not exotic pairing) can coexist with the hidden Zeeman field. The large spin splitting creates a robust topological region in parameter space, not a fine-tuned corner.
The resulting topological superconductor supports Majorana boundary modes — including unidirectional chiral edge states — without any applied field. Field-free topological superconductivity from the material's own magnetic order.
The hidden field is Zeeman physics without Zeeman cost. The magnetic order splits the bands (which topology needs) without pair-breaking (which superconductivity can't tolerate). The odd parity is what makes both possible simultaneously.