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Spatial Impact Range of Single-Molecule Magnet (SMM) on Magnetic Tunnel Junction-Based Molecular Spintronic Devices (MTJMSDs) Marzieh Savadkoohi, Bishnu R Dahal, Eva Mutunga, Andrew Grizzle, Christopher D’Angelo, and Pawan Tyagi Magnetic Tunnel Junction-Based Molecular Spintronic Devices (MTJMSDs) are potential candidates for inventing highly correlated materials and devices. However, a knowledge gap exists about the impact of variation in length and thickness of ferromagnetic(FM) electrodes on molecular spintronics devices. This paper reports our experimental observations providing the dramatic impact of variation in ferromagnetic electrode length and thickness on paramagnetic molecule-based MTJMSD. Room temperature transport studies were performed to investigate the effect of FM electrode thickness. On the other hand, magnetic force microscopy measurements were conducted to understand the effect of FM electrode length extending beyond the molecular junction area, i.e., the site where paramagnetic molecules bridged between two FM. In the strong molecular coupling regime, transport study suggested thickness variation caused ~1000 to million-fold differences in junction conductivity. MFM study revealed near-zero magnetic contrast for pillar-shaped MTJMSD without any extended FM electrode. However, MFM images showed a multitude of microscopic magnetic phases on cross junction shaped MTJMSD where FM electrodes extended beyond the junction area. To understand the intriguing experimental results, we conducted an in-depth theoretical study using Monte Carlo Simulation (MCS) approach. MCS study utilized a Heisenberg atomic model of cross junction shaped MTJMSD to gain insights about room temperature transport and MFM experimental observations of microscopic MTJMSD. To make this study applicable for a wide variety of MTJMSDs, we systematically studied the effect of variation in molecular coupling strength between magnetic molecules and ferromagnetic (FM) electrodes of various dimensions.
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Magnetic force microscopy revealing long-range room temperature stable molecule bridge-induced magnetic ordering on magnetic tunnel junction (MTJ) pillars
Magnetic tunnel junctions (MTJs) can integrate novel single molecular device elements to overcome long-standing fabrication challenges, thus unlocking their novel potential. This study employs magnetic force microscopy (MFM) to demonstrate that organometallic molecules, when placed between two ferromagnetic electrodes along cross-junction shaped MTJ edges, dramatically altered the magnetic properties of the electrodes, affecting areas several hundred microns in size around the molecular junction vicinity at room temperature. These findings are supported by magnetic resonance and magnetometer studies on ∼7000 MTJ pillars. MFM on the pillar sample showed an almost complete disappearance of the magnetic contrast. The spatial magnetic image suggests that molecular channels significantly impacted the spin density of states in the ferromagnetic electrodes. This advancement in MTJ-based molecular devices paves the way for a new generation of commercially viable logic and memory devices controlled by molecular quantum states at near-room temperatures.
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- Award ID(s):
- 1914751
- PAR ID:
- 10576936
- Publisher / Repository:
- American Institute of Physics
- Date Published:
- Journal Name:
- AIP Advances
- Volume:
- 15
- Issue:
- 3
- ISSN:
- 2158-3226
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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