Dynamical unmasking of $p$-wave magnetism by ac spin and dc orbital polarizations

Abstract

Odd-parity magnets have strong spin polarization in momentum space but no net magnetization, making their spin texture hidden from conventional magnetometry. We show that a monochromatic electric field dynamically lifts this cancellation in a $p$-wave magnet. Within each drive cycle, the field produces a net ac spin polarization linear in the driving field whose interband component is resonantly enhanced at the nonrelativistic exchange gap. Because this polarization oscillates at the drive frequency, it vanishes upon period averaging. The orbital channel follows a different hierarchy: its linear response cancels in momentum space, whereas interband coherence produces a rectified dc orbital polarization at second order when the field has components parallel and transverse to the $p$-wave spin-splitting direction. Together, the ac spin and dc orbital responses dynamically unmask $p$-wave magnetism without requiring any spin-orbit coupling.