  Using density functional theory, we investigate TM-cyclopentadienyl-benzene
sandwich molecular wires (SMWs) which are composites of TM-cyclopentadienyl and
TM-benzene wires (TM = transition metal (V, Fe)). All the SMWs are found to be
highly stable ferromagnetic half-metals, showing spin switching behavior.
Transport calculations show that finite size clusters display spin filter
property when coupled with Au electrodes on either side. I-V characteristics of
all systems confirm the spin filter property, with Au-BzVCpVBz-Au displaying
exceptionally high performance. In addition to spin filtering, the
Au-BzFeCpFeBz-Au system also shows negative differential resistance (NDR).
Compression causes an abrupt reduction in magnetic moment and a transition to a
metallic phase, while stretching causes an increase in magnetic moment.
Half-metallicity is preserved for modest amounts of stretching and compression.
