  Dream of developing molecule-based logic and memory device is more than
70-year-old. Presently, molecule-based devices are also considered for quantum
computation hardware. The recent studies have shown the molecule connected to
metal leads can perform the qubit-based logic operation. This is an interesting
question of why experimental progress is still very slow even when the scope of
molecule-based devices may govern the advancement of next-generation logic and
memory devices for the highest possible computer technologies. Molecules have
the potential to be unmatched device elements as chemists can mass-produce an
endless variety of molecules with novel optical, magnetic, and charge transport
characteristics. However, the biggest challenge is to connect two metal leads
to target molecules and develop a robust and versatile device fabrication
technology that can be adopted for commercial-scale mass production. This paper
discusses the distinct advantages of utilizing commercially successful magnetic
tunnel junctions as a vehicle for developing molecular electronics and
molecular spintronics devices. We describe the use of a tunnel junction with
the exposed sides as a testbed for molecular devices. On the exposed sides of a
tunnel, junction molecules are bridged across an insulator by chemically
bonding with the two metal electrodes; sequential growth of
metal-insulator-metal layers ensures that separation between two metal
electrodes is controlled by the insulator thickness to the molecular device
length scale. Here we also strongly emphasize a need for close collaboration
between chemists and magnetic tunnel junction researchers. Such partnerships
will have a strong potential to develop magnetic tunnel junction based
molecular devices for the futuristic areas such as memory devices, magnetic
metamaterials, and high sensitivity biosensors.
