Tunnel magnetoresistance of a natural protein molecule

Abstract

The coherent spin transport in a natural protein molecule sandwiched between ferromagnetic electrodes was analyzed based on first-principle calculations in the presence of spin–orbit coupling. The helical peptides exhibited high absolute values of the tunnel magnetoresistance ratio above 0.50. The energy level of the highest-occupied molecular orbital (HOMO) was very close to the Fermi level and sensitively responded to a change in the magnetic configuration of the electrodes. In addition, the HOMO had wave functions consisting of atomic orbitals at specific amide groups that were derived from the close-packed helical peptide structure.