Magnetic Tunnel Junction — Spin-Dependent Tunneling Magnetoresistance

This simulator renders a real magnetic tunnel junction: two ferromagnetic electrodes separated by a thin MgO barrier, with electrons crossing purely by quantum tunneling. Rotating the free layer's magnetization relative to the fixed layer changes the tunneling conductance exactly as the Slonczewski angular formula predicts, sweeping smoothly between the low-resistance parallel state and the high-resistance antiparallel state — the tunneling magnetoresistance (TMR) effect described by Julliere's model. Spin polarization and barrier thickness are both live controls, with the barrier's exponential WKB decay driving junction resistance across orders of magnitude, and a two-current particle stream visualizes majority- and minority-spin electrons tunneling at rates set by the live physics.