  Newly fabricated monolayer phosphorene and its few-layer structures are
expected to be promising for electronic and optical applications because of
their finite direct band gaps and sizable but anisotropic electronic mobility.
By first-principles simulations, we show that this unique anisotropic
conductance can be controlled by using simple strain conditions. With the
appropriate biaxial or uniaxial strain, we can rotate the preferred conducting
direction by 90 degrees. This will be of useful for exploring quantum Hall
effects, and exotic electronic and mechanical applications based on
phosphorene.
