Magnetoresistive random-access memory

Magnetoresistive random-access memory (MRAM) stores data in magnetic states rather than electrical charge. In common designs, a magnetic tunnel junction’s resistance encodes each bit.

Tunnel magnetoresistance: A change in electrical resistance caused by electron tunneling through an insulating barrier between magnetic layers. It creates the resistance contrast used to read stored bits.
Embedded MRAM: MRAM integrated into a processor or system-on-chip as on-chip memory. It can replace embedded nonvolatile memories in microcontrollers and other chips.
Dynamic random-access memory: Volatile memory that stores each bit as charge in a capacitor and periodically refreshes it. DRAM offers dense, fast working memory but loses data without power.
Giant magnetoresistance: A large resistance change in magnetic multilayers when the relative alignment of their magnetic layers changes. Its discovery established the broader technological value of spin-dependent resistance.
Spin-transfer torque: A transfer of angular momentum from spin-polarized electrons that can change a magnetic layer’s orientation. It switches bits in widely used spin-transfer-torque MRAM cells.
Cache memory: Small, fast memory that stores data a processor is likely to need soon. MRAM’s speed and nonvolatility make it a candidate for persistent caches.
Static random-access memory: Volatile memory that stores each bit in a transistor latch while power is supplied. SRAM is a common cache technology, but it requires continuous power to retain data.
Albert Fert: A French physicist who shared the 2007 Nobel Prize in Physics for discovering giant magnetoresistance. His work helped launch the spintronics research that underpins MRAM.
Spin-orbit torque: A torque on magnetization generated by spin currents produced through spin-orbit interactions. It offers a switching method that can separate write and read current paths.
Nonvolatile memory: Memory that retains stored information when electrical power is removed. MRAM belongs to this family while offering different speed and endurance tradeoffs.

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