Abstract. A heat pump model utilizing the Dufour effect is proposed, and studied by numerical and theoretical analysis. Numerically, we perform MD simulations of this system and measure the cooling power and the coefficient of performance (COP) as figures of merit. Theoretically, we calculate the cooling power and the COP from the phenomenological equations describing this system by using the linear irreversible thermodynamics and compare the theoretical results with the MD results.
Magnetic field-free switching of a three-terminal perpendicular magnetic tunnel junction (MTJ) driven by spin-orbit torque (SOT) and spin-transfer torque (STT) in the presence of a voltage-controlled magnetic anisotropy (VCMA) effect was investigated using micromagnetic simulation at 300 K. The VCMA effect assists or hinders magnetization switching depending on the polarity of the applied voltage. Thus, the impact of these effects on switching probabilities was evaluated using two write voltage pulses (VSOT, VSTT). By optimizing the configuration of these voltage pulses, we demonstrated 100 successful switchings out of 100 trials within 3.2 ns under a limited voltage of 1.0 V. In addition, the write power consumption for SOT-STT writing with optimal pulse configurations was found to be one order of magnitude lower than that of STT-alone writing. We also found that the SOT-STT writing has the great potential in practical use than the external magnetic field assisted SOT-writing. The field-free, reliable, and deterministic SOT-STT switching with low power consumption offers significant advantages for embedded memory applications.
We have studied the thermal stability and switching behavior of the recently proposed dynamic dual (DD-) magnetic tunnel junction (MTJ) with a fixed and a switchable reference layer and quad-interface (Quad-) MTJ with double-stacked free layers using micromagnetic simulation. We found that the upper free layer of the Quad-MTJ acts as a switchable reference layer with a considerably large saturation magnetization (Ms). We also found that both the thermal stability and switching time increase with an increase in the Ms of the switchable reference layer. A detailed understanding of these characteristics is critical in order to use these MTJs as embedded memories.
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