magnetic anisotropy and exchange interactions at molecule substrate spin interfaces

Abstract

In the last couple of decades, molecular spintronics has emerged, exploiting the newlinespin of molecules to design magneto-electronic devices. Recently, the development newlineof understanding the fundamental processes at the hybrid interface of the magnetic newlinemolecules and various magnetic/non-magnetic substrates has paved the path toward newlineinterface-assisted molecular spintronics. The nature of the magnetic exchange in- newlineteractions between different magnetic centers and the inherent magnetic anisotropy newlineof an individual magnetic center are the two vital magnetic properties that provide newlineturnability. Despite the fact that various experimental reports in conjunction with newlineab initio quantum mechanical calculations have advanced the evolution in this field, newlinethe interface-mediated control of those magnetic parameters remains an open area newlineof research. This thesis explores the effect of structural dynamics on the magnetic newlineproperties of the molecules at the molecule/substrate interfaces. newlineThe porphyrins and other tetrapyrrole macrocycles possess various functional newlineproperties and have already been marked as essential components in molecular spin- newlinetronics and single molecular devices. We have studied a series of tetra-coordinated newlineiron (II) porphyrins with various substitutions at the peripheral macrocyclic rings, newlineapplying first-principle calculations. The spin-state-dependent nature of the chem- newlineical bonds and spin polarization on the N-atoms play a crucial role in the vibra- newlinetional dynamics of the central Fe-atom. Theoretical nuclear resonance vibrational newlinespectroscopy (NRVS) is adopted to investigate the vibrational dynamics, Fe-atom- newlineassociated spectral peaks, and their spin-dependent features. We find that NRVS newlinestudies and iron pre-K-edge X-ray absorption analysis convincingly provides infor- newlinemation on the spin state, which could be utilized to establish a new methodology to newlineidentify the spin states without adopting any magnetic probes. On the other hand, newlinestudying magnetic properties, especially the magnetic anisotropy of iron porphyrin newlineco