Metal-Controlled Magnetoresistance at Room Temperature in Single‑Molecule Devices

The
appropriate choice of the transition metal complex and metal
surface electronic structure opens the possibility to control the
spin of the charge carriers through the resulting hybrid molecule/metal spinterface in a single-molecule electrical contact at room
temperature. The single-molecule conductance of a Au/molecule/Ni junction
can be switched by flipping the magnetization direction of the ferromagnetic
electrode. The requirements of the molecule include not just the presence
of unpaired electrons: the electronic configuration of the metal center
has to provide occupied or empty orbitals that strongly interact with
the junction metal electrodes and that are close in energy to their
Fermi levels for one of the electronic spins only. The key ingredient
for the metal surface is to provide an efficient spin texture induced by the spin–orbit coupling in the topological surface
states that results in an efficient spin-dependent interaction with
the orbitals of the molecule. The strong magnetoresistance effect
found in this kind of single-molecule wire opens a new approach for
the design of room-temperature nanoscale devices based on spin-polarized
currents controlled at molecular level.