During an experimental preparation, the contamination induced by chemical species usually leads to transport properties instabilities of molecular devices. In the present work, the density functional theory and nonequilibrium Green's functions are used to investigate the spin-transport properties of a manganese phthalocyanine-based spin valve. For the pristine spin valve, its magnetoresistive ratio can reach 103, indicating important application values in future circuits. However, the magnetoresistive effects are significantly weakened when the device is contaminated by the group NO or CO. The...
