This letter presents energy-efficient MgO based magnetic tunnel junction (MTJ) bits for high-speed spin transfer torque magnetoresistive random access memory (STT-MRAM). We present experimental data illustrating the effect of device shape, area, and tunnel-barrier thickness of the MTJ on its switching voltage, thermal stability, and energy per write operation in the nanosecond switching regime. Finite-temperature micromagnetic simulations show that the write energy changes with operating temperature. The temperature sensitivity increases with increasing write pulsewidth and decreasing write voltage. We demonstrate STT-MRAM cells with switching energies of < 1 pJ for write times of 15 ns.
Bibliographical noteFunding Information:
Manuscript received September 5, 2010; revised September 23, 2010; accepted September 24, 2010. Date of publication November 9, 2010; date of current version December 27, 2010. This work was supported in part by the Defense Advanced Research Projects Agency STT-RAM Program and in part by the Nanoelectronics Research Initiative through the Western Institute of Nanoelectronics. The review of this letter was arranged by Editor L. Selmi.
- Magnetic tunnel junctions (MTJs)
- magnetoresistive random access memory (MRAM)
- nonvolatile memory
- spin transfer torque (STT)