Spatial Impact Range of Single Molecule Magnet on Magnetic Tunnel Junction-Based Molecular Spintronic Devices (MTJMSDs)

Unprecedented advancement of technology over the past few decades, has raised the needs of having more efficient logic and memory devices. Magnetic Tunnel junction based Molecular Spintronic Devices (MTJMSD) can effectively combine ferromagnetic electrode (FME) with magnetic molecules and be potential candidates for making metamaterials and highly correlated systems. This work investigates the effect of FME’s length and thickness variation on MTJMSD’s molecule-induced correlated magnetic phases and spatial range of molecule impact. Our experimental transport studies show that in a strong FME-molecule coupling regime 10 to 20 nm change in thickness changed MTJMSD conductivity by&gt;1000 fold. Magnetic Force Microscopy (MFM) showed the FME extending beyond the cross-junction area developed multiple room temperature stable magnetic phases. To explore other possible effects, we also conducted Monte Carlo Simulation (MCS) using Heisenberg atomic modeling. Our computational results agree with our experimental observations. According to the MCS study, increasing FME length produced multiple magnetic phases around MTJMSD. On the other hand, increasing FME thickness from 5 to 25 atoms reduced the penetration of molecule coupling impact along the thickness.<br/><br/>We have studied FME electrode including 1250, 2500, 5000,7500 and 10000 atoms. We studied correlation between molecule spin state and FME as a function of length and width. We also studied the spatial magnetic susceptibility of MTJMSD as a function of FME length and thickness. We observed that molecular coupling strength required to produce long range impact on MTJMSD with different FME lengths did not vary noticeably. However, variation in FME thickness caused critical molecular coupling strength required to produce strong coupling changed from 0.15 to ~0.65 as FME thickness changed from 5 to 25 atoms. MCS results matches with our experimental observation of thickness and length effect.