Single molecule magnet’s (SMM) effects on antiferromagnetbased magnetic tunnel junction

Abstract

Single-molecule magnets (SMMs) are pivotal in molecular spintronics, showing unique quantum behaviors that can advance spin-based technologies. By incorporating SMMs into magnetic tunnel junctions (MTJs), new possibilities emerge for low-power, energy-efficient data storage, memory devices and quantum computing. This study explores how SMMs influence spin-dependent transport in antiferromagnetbased MTJ molecular spintronic devices (MTJMSDs). We fabricated cross-junction MTJ devices with an antiferromagnetic Ta/FeMn bottom electrode and ferromagnetic NiFe/Ta top electrode, with a ∼2 nm AlOx layer, designed so that the AlOx barrier thickness at the junction intersection matched the SMM length, allowing them to act as spin channels bridging the two electrodes. Following SMM treatment, the MTJMSDs exhibited significant current enhancement, reaching a peak of 40 μA at 400 mV at room temperature. In contrast, bare MTJ junctions experienced a sharp current reduction, falling to the pA range at 0○C and remaining stable at lower temperatures—a suppression notably greater than in SMM-treated samples (Ref: Sankhi et al., Journal of Magnetism and Magnetic Materials, p. 172608, 2024). Additional vibration sample magnetometry on pillar shaped devices of same material stacks indicated a slight decrease in magnetic moment after incorporating SMMs, suggesting an effect on magnetic coupling of molecule with electrodes. Overall, this work highlights the promise of antiferromagnetic materials in optimizing MTJMSD devices and advancing molecular spintronics.