Magnetic proximity has been observed in a variety of solid-state magnetic devices, but has been less discussed at the molecular scale. In this study, the magnetotransport calculation is carried out using the generalized Landau-Lifshitz-Gilbert (LLG) equation combined with density functional theory (DFT) and our self-developed junpy calculated spin-torque effect. Except for the current driven spin torque, which is a promising approach for magnetization switch in magnetic random access memory, the equilibrium field-like spin torque also plays a crucial role in the strain-controlled exchange bias with current-controlled magnetic coercivity in single-molecule magnetic junctions. The tight-binding model is further employed to clarify the critical role of the interfacial spin filter effect arising from the hybridization between the linker and Co apex. These multidisciplinary DFT+JunPy+LLG results may provide important and practical implications in the dual control of magnetic proximity and magnetization switching in molecular spintronics at low temperature, either by tensile strain or via smaller applied current density of the order of MA/cm2.
The DFT+JunPy+LLG calculated magnetization hysteresis curves (mz-H) for Co/BDA/Co and Co/BDT/Co single-molecule magnetic junctions (SMMJs) under various tensile strains at zero temperature. The gray shaded area represents the field region between ±μ0Hk. The HC1 (HC2) is the threshold field required for P-to-AP (AP-to-P) magnetization switching, where P and AP denote the parallel and antiparallel, respectively.Current dependence of DFT+JunPy+LLG calculated μ0HC1 and μ0HC2 for Co/BDA/Co and Co/BDT/Co SMMJs under various tensile strains at zero temperature. The black vertical arrows and purple shaded areas represent the strain control and current control of the threshold fields, HC1 and HC2, respectively. The HC1 (HC2) is the threshold field required for P-to-AP (AP-to-P) magnetization switching.Finite writing pulse phase diagrams for DFT+JUNPY+LLG calculated (a) Co/BDA/Co and (b) Co/BDT/Co SMMJs without strain at various temperatures ranging from 0 to 100 K. The time step is 10 ps, and the integration time is 0.1μs in each field point. Each diagram is averaged with 10 identical simulations with different random noise.
