Interface-Assisted Room-Temperature Magnetoresistance in Cu-Phenalenyl-Based Magnetic Tunnel Junctions

Abstract

Delocalized carbon-based radical species with unpaired spin, such as the phenalenyl (PLY) radical, have opened avenues for developing multifunctional organic spintronic devices. Using direct laser writing and in situ deposition, we successfully fabricated Cu-PLY- and Zn-PLY-based organic magnetic tunnel junctions (OMTJs) with improved morphology and a reduced junction area of 3 × 8 μm2. The nonlinear and weakly temperature-dependent current–voltage (I–V) characteristics in combination with the low organic barrier height suggest tunneling as the dominant transport mechanism in the structurally and dimensionally optimized OMTJs. Cu-PLY-based OMTJs show significant magnetoresistance up to 14% at room temperature due to the formation of hybrid states at the metal–molecule interfaces called “spinterface”, which reveals the importance of spin-dependent interfacial modification in OMTJs’ design. Additionally, at high bias, in the absence of a magnetic field, OMTJ shows stable voltage-driven resistive switching. Cu-PLY having spin 1/2 with net magnetic moment demonstrates magnetic hardening between the surface molecule at the Co interface and gives rise to stable MR, which suggests its use as a feasible and scalable platform for building molecular-scale quantum memristors and processors.