The working principle of an MTJ relies on the concept of quantum tunneling. When the magnetic moments (spins) of the two ferromagnetic layers are aligned parallel, the probability of electron tunneling through the insulator is high, resulting in a low resistance state. Conversely, when the magnetic moments are anti-parallel, the tunneling probability decreases, and the MTJ exhibits a high resistance state. This change in resistance is known as Tunnel Magnetoresistance (TMR).
