Negative effective mass induced by in-plane magnetic fields in n-doped wide quantum wells

By solving the coupled Schroedinger and Poisson's equations self-consistently, we have theoretically investigated the in-plane magnetic-field-induced negative effective mass (NEM) in n-doped wide quantum wells. The NEM originates from the interaction of Hartree potential and magnetic-field-introduced potential. Without n-type doping, no NEM section arises at any magnetic field densities. The value of NEM and the width of NEM section can be effectively adjusted by magnetic field, electrical field, and doping concentration, which make it possible to utilize the above system to realize the tunable terahertz source