Design and analysis of SHE-assisted STT MTJ/CMOS logic gates

Abstract

We have investigated the spin-Hall effect (SHE)-assisted spin transfer torque (STT) switching mechanism in a three-terminal MTJ device developed using p-MTJ (perpendicular magnetic tunnel junction) and heavy metal materials of high atomic number, which possesses large spin–orbit interaction. Using p-MTJ schematic and complementary-metal-oxide-semiconductor (CMOS) logic, we have designed three basic hybrid logic-in-memory structure-based logic gates NOR/OR, NAND/AND, and XNOR /XOR. Then the performances of these hybrid gates are evaluated and the results are compared with the conventional CMOS-based gates in terms of power, delay, power delay product, and device count. From the analysis, it is concluded that SHE-assisted STT MTJ/CMOS logic gates are nonvolatile, consume less power, and occupy a smaller die area as compared to conventional CMOS only logic gates.

Spin Orbit Torque-Assisted Magnetic Tunnel Junction-Based Hardware Trojan

“…Spintronic hardware Trojans depend on external factors like magnetic field and temperature due to their unique physical characteristics, which can be exploited for external triggering. The hybrid CMOS and MTJ circuits [23] can replace some of the logic gates, and careful designing can make them implement the same functionality with competitive switching, area, and energy consumption compared to the CMOS gates. Reference [24] reports that the amplitude of low-order leakages in masked implementations can be amplified externally by tweaking side-channel measurement setups in a way that is under the control of a power analysis adversary.…”

“…The LLG solver described in the Verilog-A model is used to solve the magnetic dynamics of the MTJ. A detailed switching mechanism for the model is provided in [23]. The MTJ-based hardware Trojan block is shown in Figure 3b.…”

“…Nevertheless, it is challenging to detect the proposed Trojan designed in this work for the following reasons: (1) Difficulty in achieving high coverage of every net. (2) Spintronics-based devices utilize low operational voltage, competitive cell area, and delay [23]; thus, minor deviations in such parameters under process and environmental variation are very hard to detect. In complex SoC with sneaky Trojans, the side channel effects can be masked due to such effects.…”

Physically Unclonable Function Using GSHE Driven SOT Assisted p-MTJ for Next Generation Hardware Security Applications

“…The compact model for the circular perpendicular magnetic anisotropy (PMA) MTJ selected is presented in [31] and the simulation parameters are selected based on the experimentally determined MTJ stack presented in section III C for a more realistic PUF simulation. The detailed switching mechanism for the model is provided in [32].…”

Reconfigurable spintronic logic gate utilizing precessional magnetization switching

“…On the other hand, although the logic gate functionality AND and OR have been proposed by adjusting the threshold switching current density of the MTJ, a straightforward solution for XOR function is still absent. Particularly, the realization of XOR function requires a preprocessing of the input signal, or otherwise the cascading of multiple memory cells, leading to a substantial increase in power consumption and the circuitry complexity [17][18][19][20][21][22]. In general, the roadmap in developing the SOT-MRAM cell for the IMC application is largely elusive up to now.…”