Thermoelectric studies of electronic properties of ferromagnetic GaMnAs layers

Osinniy, V.; Dybko, K.; Jedrzejczak, A.; Arciszewska, M.; Dobrowolski, W.; Story, T.; Radchenko, M. V.; Sichkovskiy, V. I.; Lashkarev, G. V.; Olsthoorn, S. M.; Sadowski, J.

Thermoelectric studies of electronic properties of ferromagnetic GaMnAs layers

Authors

Description

Thermoelectric power, electrical conductivity, and high field Hall effect were studied over a broad temperature range in ferromagnetic Ga(1-x)Mn(x)As epitaxial layers (0.015<x<0.06). Thermoelectric power analysis gives the information about carrier transport mechanisms in layers with both metallic and non-metallic type of conductivity and allows determination of the Fermi energy and carrier concentration. At high temperatures (T>70 K) the thermoelectric power in GaMnAs linearly increases with increasing temperature. That indicates the presence of a degenerate hole gas with the Fermi energy EF=220+-25 meV, nearly independent of Mn content (for 0.02<x<0.05). At lower temperatures GaMnAs layers with metallic-type conductivity show an additional contribution to the thermoelectric power with the maximum close to the Curie temperature. The layers exhibiting insulating electrical properties show 1/T-type increase of thermoelectric power at low temperatures.
21 pages, 8 figures