Seminar: Dr Gerd Kunert EIT+ Wroclaw Research Centre, Poland


March 5, 2015 - 12:15 pm


March 5, 2015 - 1:00 pm


Victoria University of Wellington RB901   View map

Ferromagnetism in (Ga,Mn)N

Dr Gerd Kunert EIT+ Wroclaw Research Centre, Poland

The dilute magnetic semiconductor (DMS) (Ga,Mn)N has gained large research interest after calculations predicted ferromagnetism higher than room temperature in the year 2000 [1].  The theoretical predictions were based on the so called Zener model which assumes holes as  carriers of the spin information. Soon afterwards many different spintronic applications seemed to be within reach. Examples are the spin transistor or memory devices based on the electron spin. Despite the large research effort which followed quickly afterwards no applications based on magnetic semiconductors are commercially available up to now. In the talk the latest findings will be presented about the magnetic and electronic properties of epitaxial (Ga,Mn)N layers fabricated by molecular beam epitaxy. Ellipsometric data and resistance measurements show that carriers provided by Mn are energetically trapped in the bandgap of the host material and make (Ga,Mn)N highly insulating. Nevertheless the material is ferromagnetic and has the largest magnetization ever reported for any DMS. Ferromagnetic transition temperatures of undoped (Ga,Mn)N layers are below 13 K which is relatively low. Different types of doping strategies will be presented to insert free holes in the material and therefore increases those low Curie temperatures of the material.

[1] T. Dietl, et al. Science 287, no. 5455, pp. 1019-1022 (2001)

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