Characterizing Single Molecular Spin State Effects on Magnetic Tunnel Junction-Based Molecular Spintronics Devices Using Monte Carlo Simulations

Magnetic tunnel junction molecular spintronics devices (MTJMSDs) are metamaterials realized by simultaneously connecting Single Molecular Magnets (SMM) between two ferromagnetic (FM) electrodes of an optimized magnetic tunnel junction (MTJ)¹. SMM-FM interactions produce novel optical, electronic, and magnetic properties. SMMs exhibit a wide range of spin states (Sm), which is experimentally challenging to quantify. Here, we report Monte Carlo Simulations (MCS) exploring SMM's Sm impact on the MTJMSD equilibrium state. This study used 3D Ising model of MTJMSD to conduct MCS. Following a Markov process, the device's temporal and spatial magnetic moments were analyzed as a function of Sm (0-4) and thermal energy (0.01-0.5). We found that anti-FM coupling occurred when a paramagnetic SMM made anti-FM and FM coupling to the first and the second FM electrodes, respectively. Moreover, we found that the SMM spin state's magnitude must be above 0.2 to create a significant impact on the MTJMSD's magnetic properties. Our MCS also showed that SMM's spin impacted the spatial correlation length scale. We also studied impact of SMM's spin state on the heat capacity and magnetic susceptibility properties of MTJMSDs.

1. P. Tyagi, C. Baker and C. D’Angelo, Nanotechnology 26 (30), 305602 (2015).