Data are written by small electrical currents in the write lines that create a magnetic fields, which flip electron spins in the spin-dependent tunnel junction storage layer, thus changing the junction’s resistance. Data is read by the tunneling current or resistance through the tunnel junction.
Next-generation MRAM could reduce cell size and power consumption. Potential next-generation designs include Spin-Momentum Transfer, Magneto-Thermal MRAM, and Vertical Transport MRAM. Spin-Momentum Transfer (also “Spin-Transfer,” “Spin Injection,” or “Spin Torque Transfer”) MRAM is based on changing the spin of storage electrons directly with an electrical current rather than an induced magnetic field. This method has the potential to significantly reduce MRAM write currents, especially with lithographic feature sizes less than 100 nanometers. M-T MRAM uses a combination of magnetic fields and ultra-fast heating from electrical current pulses to reduce the energy required to write data. Vertical Transport MRAM (VMRAM) is a high-density type of MRAM that employs current perpendicular to the plane to switch spintronic memory elements.