  We report a first-principles study on the tunnel magnetoresistance (TMR) and
spin-injection efficiency (SIE) through phosphorene with nickel electrodes
under the mechanical tension and bending on the phosphorene region. Both the
TMR and SIE are largely improved under these mechanical deformations. For the
uniaxial tension ($\varepsilon_y$) varying from 0 to 15\% applied along the
armchair transport ({\it y}-)direction of the phosphorene, the TMR ratio is
enhanced with a maximum of 107\% at the $\varepsilon_y=10\%$, while the SIE
increases monotonously from 8\% up to 43\% with the increasing of the strain.
Under the out-of-plane bending, the TMR overall increases from 7\% to 50\%
within the bending ratio of 0-3.9\%, and meanwhile the SIE is largely improved
to around 70\%, as compared to that (30\%) of the flat phosphorene. Such
behaviors of the TMR and SIE are mainly affected by the transmission of spin-up
electrons in the parallel configuration, which is highly depended on the
applied mechanical tension and bending. Our results indicate that the
phosphorene based tunnel junctions have promising applications in flexible
electronics.

Materials Science