ANOMALOUS TUNNELING TRANSPARENCY OF DOUBLE-BARRIER QUANTUM-WELLS WITHTRANSITION-METAL IMPURITIES

A mechanism for the anomalous transparency of a double-barrier quantum well (DBQW) doped with transition-metal impurity is proposed. Apart f rom the usual resonance peaks, strong features appear in the tunneling transparency, since such a DBQW possesses its own quasi-two-dimension al (2D) continuum together with the impurity level. These strong peaks arise near the edges of 2D bands due to the reconstruction of 2D cont inuum states in a process of tunneling via a doped DBQW. As a result, the tunneling transparency can have peaks even when the deep impurity level is out of resonance with the chemical potential. Unlike the well -known Kondo singularities, the impurity-induced resonances are temper ature independent. The influence of Kondo scattering on these features is also considered.