Dresden 2009 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 37: Transport: Nanoelectronics II - Spintronics and Magnetotransport
TT 37.5: Vortrag
Donnerstag, 26. März 2009, 10:30–10:45, HSZ 105
Magnetic and transport properties of ferromagnet / semiconductor Heterostructures (Ga,Mn)As/GaAs — •S R Dunsiger1, T Goko2,3, J P Carlo2, G Nieuwenhuys4, T Prokscha4, E Morenzoni4, D Chiba5, T Tanikawa5, F Matsukura5, H Ohno5, R H Heffner6, and Y J Uemura2 — 1Physik Dept E21, TU München, Garching, Germany — 2Dept of Physics, Columbia University, New York, USA — 3TRIUMF, Vancouver, Canada — 4PSI, Villigen, Switzerland — 5Laboratory for Nanoelectronics and Spintronics, RIEC, Tohoku University, Sendai, Japan — 6LANL, Los Alamos, USA
Ferromagnet-Semiconductor heterostructures show immense promise for device applications, in particular in the injection of polarised spins into a semiconducting substrate. More fundamentally, the III-V semiconducting materials (Ga,Mn)As exhibit unusual long range indirect exchange interactions between Mn ions, where the Mn atoms simultaneously act as a magnetic species and charge donors. An intriguing link between the magnetic and transport properties is hence implied.
Low-energy µ SR, in addition to magnetization and transport measurements on specimens with Mn concentrations between 1.0 and 3.4 % are reported. Ferromagnetism with a sharp onset temperature and nearly 100 % volume fraction is observed, at odds with debate over the rather inhomogeneous nature of the phase transitions. In addition, the semiconductor-to-metal transition and paramagnetic-to-ferromagnetic transitions occur at different Mn concentrations, while unusually, even a semiconducting film shows static ferromagnetism developing.