Tunnel magnetoresistance of a molecular chain homo-catenated by group IV elements

Abstract

Spin conduction in a molecular chain homo-catenated by group IV elements is calculated using the first-principle density functional theory. In particular, the characteristics of the tunnel magnetoresistance (TMR) are remarked upon. The germanium and tin molecular chains, which have σ-conjugation in the main chain, exhibit relatively high TMR ratios and retain these values up to a bias voltage of 0.3 V. It is found that the considerable difference in TMR effects between the carbon molecule and the σ-conjugated molecular chain is dependent on the spin polarization of the linking group between the nickel electrode and the main chain. The σ-conjugated molecular chains would thus be suitable for application to TMR devices.