Four-valued magnetic random access memory based on magneto tunnel junction and resonant tunneling diode
We proposed a novel four-valued magnetic random access memory (MRAM), that uses a double barrier magneto tunnel junction (MTJ) and a resonant tunneling diode (RTD) connected in series. The double barrier MTJ in the form FM1/I/FM2/I/FM1, where FM1 and FM2 represent ferromagnetic materials with different coercive forces and I represents an insulator, respectively, can take four distinct resistance values, depending on the direction of magnetization of each ferromagnetic layer. The RTD can increase the magneto-resistance (MR) ratio of the MTJ without area penalty due to the NDR characteristics and compactness. The circuit simulation showed that the GaAs/A1As-based triple barrier RTD with its peak-to-valley current ratio of 20 increased the effective MR ratio from 15% to more than 1700%. The cell area per bit is 2F(2)/bit, which is suitable for a ultra-high density memory.
resonant tunnel diode ndr characteristics multivalued mram double-barrier mtj