Robust Magnetic Tunnel Junction-Based Molecular Spintronics Devices for Harnessing Molecular Quantum Properties*

Molecule are the smallest mass-producible nanostructure with exotic quantum properties. Harnessing them as the device element has been focus of research for >70 years. However, conventional methods of connecting molecules with the two metal electrodes produce low yield and very limited in scope. This talk will discuss our magnetic tunnel junction based molecular device (MTJMSD) approach as a solution to many long-standing fabrication challenges. Here, we report fabrication process to realize robust cross-junction shaped MTJMSD where the minimum gap between the two ferromagnetic electrodes is tailored with the help of alumina insulator-along the two exposed side edges. Molecules of interest are bridged across the insulating gap to serve as the dominant spin channels. Two exposed side edges are produced using liftoff-method and has been discussed elsewhere. MTJMSD's robustness critically depend on the quality of insulating tunnel barrier. We have systematically optimized several factors using multiple Taguchi Design of Experiment approach. For this study optimized sputtering process parameters such as RF sputtering power, gas pressure, argon-oxygen gas ratio, etching parameters. We successfully produced >95% yield of robust ~4 nm tunnel barrier with 20-40 nA tunneling current at 100 mV to serve as testbed for MTJMSD realization.