MAMR (microwave-assisted magnetic recording)
Microwave-assisted magnetic recording, which uses a spin-torque oscillator to shake magnetic grains into flipping more easily — an alternative to HAMR's laser.
Like HAMR, MAMR attacks the superparamagnetic limit so denser media can still be written — but without heat. A spin-torque oscillator built into the write head emits a microwave-frequency field (tens of GHz) that drives the target grains into ferromagnetic resonance, lowering the field needed to reverse them. Championed by Western Digital, early products used a milder variant — energy-assisted, ePMR — rather than full MAMR, while HAMR reached market first at Seagate. The appeal is reusing more of the conventional head and avoiding a laser and exotic FePt media; the challenge is building a reliable oscillator that survives inside the head.