Green’s function investigation of quantum transport and current patterns in 2D electronic system under spatially modulated magnetic fields

Using the recursive non-equilibrium Keldysh Green’s function formalism, the conductance and current patterns in two-dimensional electronic system (2DES) under spatially modulated magnetic fields are studied. The quantized conductance platforms are found for both B = 0.0 T and a homogeneous magnetic field B = 2.0 T. The results are in agreement with their corresponding band structures. However, the applied magnetic field is often inhomogeneous. By depositing a ferromagnetic strip at the top of 2DES, the stray magnetic field can be produced around the strip. Such magnetic field is adopted widely in many previous studies. Our computed result shows that the conductance is suppressed dramatically and some conductance peaks are found at the low-Fermi energy region. These peaks originate from resonant transmission via quasilocalized states. LDOS and differential conductance patterns also suggest the corresponding states are really localized in a small region. We also investigate the conductance for the cases of different magnetic field magnitudes. It is found, with applied magnetic field increasing, the conductance suppression is more and more significant and the threshold Fermi energy for current flow is shifted to high-energy region.