A Monte Carlo study of molecular nanostructure based spintronics devices

Molecule spintronics devices (MSDs) are capable of harnessing the controllable transport and magnetic properties of molecular device elements and can revolutionize computer logic and memory. A MSD is realized by placing magnetic molecule(s) between the two ferromagnetic electrodes. Recent experimental studies exhibits that some magnetic molecules yielded unparalleled strong exchange couplings between the two ferromagnets, leading to intriguing magnetic and transport properties in a MSD. Further growth of MSDs will depend on gaining an in-depth understanding of the molecule induced exchange coupling, and its impact on MSD´s switchability, functional temperature range, stability etc. However, the large size of MSD systems and unsuitable device designs are the two biggest hurdles in theoretical and experimental studies of magnetic attributes produced by molecules in a MSD. This paper theoretically studies the MSD systems by performing Monte Carlo simulations (MCS). The effect of magnetic molecule induced exchange coupling was studied at different temperature. For these studies MSDs were represented by a 2D Ising model. Our MCS shows that thermal energy strongly influenced the molecular coupling effect in a MSD. We studied the effect of a wide range of molecule-metal electrode couplings on the fundamental properties of MSDs. If molecules induced exchange coupling increased beyond a threshold limit a MSD developed dramatically new magnetization, specific heat, and magnetic susceptibility attributes. Our MCS exhibited that the transition points in MSD´s magnetic properties was the interplay of temperature and molecular coupling strength. These simulations will allow the understanding of fundamental device mechanisms behind the functioning of novel MSDs. Our MSD model represents many magnetic nanostructures and ferromagnetic electrodes combinations promising for realizing futuristic spintronics devices.