Dresden 2017 – wissenschaftliches Programm
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MA: Fachverband Magnetismus
MA 65: Poster 2
MA 65.31: Poster
Freitag, 24. März 2017, 09:30–13:00, P2-OG1
Possible Polaron Percolation in the Diluted Magnetic Semiconductors (Ga,Mn)As and (Ga,Mn)P — •Martin Lonsky1, Jan Teschabai-Oglu1, Klaus Pierz2, Hans Werner Schumacher2, Ye Yuan3, Shengqiang Zhou3, and Jens Müller1 — 1Physikalisches Institut, Goethe-Universität, Frankfurt (M), Germany — 2Physikalisch-Technische Bundesanstalt, 38116 Braunschweig, Germany — 3Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
Diluted magnetic semiconductors combine the benefits of semiconducting and magnetic materials and therefore are promising candidates for spintronics applications. For instance, (Ga,Mn)As and (Ga,Mn)P exhibit long-range magnetic order between substitutional Mn ions mediated by holes. Despite intense research efforts, there is no consensus on the development of spontaneous magnetization. An intriguing theoretical concept is the percolation of magnetic polarons as a possible origin [1]. Motivated by results of a diverging 1/f-noise magnitude in the CMR material EuB6, where the existence of percolating nanoscale magnetic clusters has been demonstrated [2], we study the low-frequency carrier dynamics by fluctuation spectroscopy. Besides insights into the defect physics of the materials, we find a power law scaling of the noise magnitude SR/R2 ∝ Rω at the percolation threshold pc with a critical exponent ω = 3.7± 0.3 for (Ga,Mn)P, which we compare with the results for (Ga,Mn)As with delocalized carriers.
[1] A. Kaminski and S. Das Sarma, Phys. Rev. Lett. 88, 247202
[2] P. Das et al., Phys. Rev. B 86, 184425