Solar Cell Effect with Magnetic Metamaterials Produced by Combining Magnetic Tunnel Junction and Magnetic Molecules

Abstract

A new class of magnetic metamaterials can be produced by placing magnetic molecules between two ferromagnetic electrodes. Magnetic molecules can be designed to create strong exchange coupling between two ferromagnetic electrodes. Magnetic molecule-induced strong exchange coupling that can be harnessed as the means to initiate an automatic spin filtering process to shuffle the spin density of states in the two ferromagnetic electrodes. Our recent preliminary experimental studies showed that iron and nickel atom-based organometallic molecules (FeNiOMC) produced a strong spin filtering effect between NiFe and Co/NiFe ferromagnetic electrodes (Tyagi, P.; Riso, C., Molecular spintronics devices exhibiting properties of a solar cell. Nanotechnology 2019, 30 (49), 49540). Fe-Ni-OMC dramatically modified the magnetic properties of ferromagnetic electrodes present in the magnetic tunnel junction testbed at room temperature. This paper talks about the resulting Fe-NiOMC and magnetic tunnel junctionbased magnetic metamaterial. This metamaterial showed an intriguing solar cell effect. Further experimental studies are conducted to design several other forms of novel magnetic metamaterials by combining a wide range of Singlemolecule magnetic (SMM) and porphyrin-like magnetic molecules with various permutations of magnetic electrodes. To produce a magnetic tunnel junction testbed that is to be used to test various molecules, we made extensive experimental optimization efforts at each stage of device fabrication to address device fabrication challenges associated with molecule-ferromagnet interactions. In this study, we have systematically optimized several factors using multiple Taguchi Design of Experiment approaches to improve the fabrication of the bottom electrode of the magnetic metamaterial. We systematically varied photolithography parameters and plasma treatment process to yield a bottom ferromagnetic electrode with