Theoretical concepts of resonant tunneling spintronics devices

Dr. Christian Ertel, University of Regensburg, Germany

Monday, December 15, 2008
11 a.m.

CSB 523


Spintronics devices aim in general in enhancing the functionality of the existing electronic technology by exploiting the spin-dependent properties of solid-state systems. In this context, band-engineered magnetic semiconductor heterostructures offer promising perspectives, since they provide a lot of opportunities for controlling and tuning spin-dependent magneto-transport properties. Especially, the rapid improve- and development of novel dilute magnetic semiconductors (DMS) in the last decades, in which semiconductors are made magnetic by doping with transition metal elements, has considerably enlarged the class of suitable materials for the growing of such magnetic heterojunction systems. In this talk several theoretical device concepts based on the resonant tunneling through magnetic double-barrier structures are presented. The concept of the digital magneto resistance is introduced, which can appear in serially connected resonant tunneling diodes (RTDs). Moreover, it is shown that the interplay of the transport and magnetic effects in ferromagnetic RTDs can lead to interesting dynamic effects such as the appearance of self-sustained current oscillations at a nominally steady bias voltage or the occurrence of magnetoelectric bistabilities.