Ferrite head
The early read/write head — a tiny ferrite core with a wire winding — that carried hard disks and floppies before thin-film and GMR took over.
A ferrite head is a tiny horseshoe of sintered ferrite (a ceramic-like iron oxide) with copper wire wound round it and a narrow gap facing the medium. Current through the coil magnetises the gap to write; passing flux reversals induce a voltage to read. Cheap and rugged, the ferrite head carried floppy drives and the first hard disks.
But the core couldn't be made small enough for high track density, and one coil did both jobs poorly. Metal-in-gap (MIG) added a thin metal layer in the gap to push it further; thin-film heads (photolithographed) then took over writing, and magnetoresistive GMR heads split off reading in the 1990s.