Magnetic Force Microscopy Revealing Molecule Impact on Magnetic Tunnel Junction Based Molecular Devices at Room Temperature Pawan Tyagi 1,2 and Christopher Riso 1 University of the District of Columbia, Department of Mechanical Engineering, 4200 Connecticut Avenue NW Washington DC-20008, USA 1 Email*: ptyagi@udc.edu University of Kentucky, Chemical and Materials Engineering Department, 177 F Paul Anderson Hall, Lexington, KY-40506, USA 2 Abstract: Commercially successful magnetic tunnel junction can harness the unmatched capabilities of molecular device elements by solving decade old fabrication issues. Utilization of magnetic tunnel junction as a testbed for molecules also enables unprecedented magnetic studies of molecular spintronics devices. This paper utilizes magnetic force microscopy (MFM) to vividly show that organometallic molecules when bridged between two ferromagnetic electrodes along the magnetic tunnel junction edges, transformed the magnetic electrodes itself. Molecules impacted several hundred- micron areas of ferromagnetic electrodes at room temperature. Complementary, magnetic resonance and magnetometer studies supported the dramatic MFM results. Molecule induced changes in the magnetic electrodes impacted the transport of the magnetic tunnel junction and stabilized as much as six orders smaller current at room temperature. Magnetic tunnel junction based molecular devices can be a gateway to a vast range of commercially viable futuristic logic and memory devices that are controlled by the molecular quantum states near room temperature. Introduction: Application of spintronics in the form of magnetic tunnel junction (MTJ), with ferromagnet-insulator-ferromagnet thin film configuration, is currently making a global impact. Transforming this commercially successful MTJs in molecular spintronics devices advances two fields simultaneously 1 . Utilization of molecules can overcome the low spin coherence of the tunnelling barriers and scattering issues at Fig. 1 Molecular spintronics devices based on (a) planar nickel nano-gap junction, (b) multiple molecular monolayers sandwiched between two ferromagnetic electrodes, (c) magnetic tunnel junction with the exposed side edges. (d)Molecules covalently bonded between two ferromagnets. (e)Magnified version of one molecule connected to the ferromagnetic electrodes via thiol groups. (f) Topographical image of a MTJ. MFM of the MTJ (g) before and (h) after the hosting molecular channels along the exposed edges.