Unusual transport property of two-dimensional semi-Dirac system modulated by magnetic barriers

We study the ballistic transport of a two-dimensional (2D) electron gas with anisotropic semi-Dirac (SD) band structure modulated by magnetic and electrical barriers. The magnetic barriers are induced by an inhomogeneous magnetic field, which can form a parallel (P) or antiparallel (AP) magnetic configuration. Using the transfer matrix approach, we calculate the transport-direction-dependent transmission and the conductance in P and AP configurations, respectively. For transport along the direction with linear dispersion, the magnetoresistance (TMR) oscillates with the Fermi energy and even varies from positive to negative due to the Klein tunneling. Whereas for transport along the direction with parabolic dispersion, the TMR is always positive, and there is a huge TMR within a range of energies due to the severe mismatch of the wavevector in the case of AP configuration. For the transport along an arbitrary direction, interestingly, the oscillation patterns of TMR are similar to those along the linear direction, but the amplitude of TMR is observably enhanced by two orders in magnitude. This unusual feature of TMR is originated from the anisotropic band structure of the system which suppresses the Klein tunneling. Our results are useful in designing magnetic memories based on 2D SD systems.