  The magneto-transport properties of phosphorene are investigated by employing
the generalized tight-binding model to calculate the energy bands. For bilayer
phosphorene, a composite magnetic and electric field is shown to induce a
feature-rich Landau level (LL) spectrum which includes two subgroups of
low-lying LLs. The two subgroups possess distinct features in level spacings,
quantum numbers, as well as field dependencies. These together lead to
anomalous quantum Hall (QH) conductivities which include a well-shape,
staircase and composite quantum structures with steps having varying heights
and widths. The Fermi energy-magnetic field-Hall conductivity
($E_{F}-B_{z}-\sigma_{xy}$) and Fermi energy-electric field-Hall conductivity
($E_{F}-E_{z}-\sigma_{xy}$) phase diagrams clearly exhibit oscillatory
behaviors and cross-over from integer to half-integer QH effect. The predicted
results should be verifiable by magneto-transport measurements in a dual-gated
system.

Mesoscale and Nanoscale Physics;Materials Science