Two experiments found a large resistance change
Fert’s group reported giant magnetoresistance in iron/chromium multilayers in 1988. Grünberg’s group found enhanced magnetoresistance in related layered structures, published in 1989. Their independent work connected magnetic configuration with electrical transport.
The often-shown large multilayer signal was measured at low temperature. The room-temperature trilayer result had a smaller amplitude; comparing them requires the sample and temperature labels.
Spin-dependent scattering changes the conducting channels
An electron’s scattering depends on its spin relative to a ferromagnetic layer. Parallel layers can offer one relatively favorable channel through the structure. Antiparallel layers force each channel to encounter a less favorable magnetic layer.
Sources: [1]
An angle curve is a limited device description
A smooth cosine-like interpolation is useful for a simple spin valve with specified parallel and antiparallel resistances. It does not derive the magnetizations from applied field, include domain reversal, or calculate interface scattering from the atomic structure.
The spin-valve Lab records the angular response
The Lab links a visible layer stack and magnetization arrows to a synthetic resistance scan. It makes relative angle the controlled quantity. The original field sweeps contain additional magnetic coupling and hysteresis physics, which the simple angular model leaves out.