Thermal, transport, and magnetotransport properties of free charge carriers in Mn-doped structures with a GaAs/InGaAs/Ga
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Thermal, Transport, and Magnetotransport Properties of Free Charge Carriers in MnDoped Structures with a GaAs/InGaAs/GaAs Quantum Well V. A. Kulbachinskiia and L. Yu. Shchurovab a
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Moscow State University, Moscow, 119991 Russia Lebedev Physical Institute, Russian Academy of Sciences, Moscow, 119991 Russia email: [email protected] Received November 20, 2008
Abstract—The results of investigation of the magnetic and transport properties of a GaAs/InGaAs/GaAs quantum well deltadoped with carbon and manganese from different sides and containing a ferromagnetic phase are analyzed. A thermodynamic model is formulated and the composition of a system consisting of neutral Mn atoms, Mn ions, and holes in the quantum well is calculated for determining the concentration of free charge carriers. The contributions to the resistance from different mechanisms of hole scattering are calculated, and good agreement with the experimental temperature dependences of the resistance is attained. The calculated and experimental values of the negative magnetoresistance associated with variation in the contribution of scattering from magnetic ions of the spinpolarized system of charge carriers are found to be in quantitative agreement. PACS numbers: 72.15.Gd, 72.20.Dp, 72.25.b, 73.43.Qt, 73.63.Hs DOI: 10.1134/S1063776109070152
1. INTRODUCTION Spintronics or magnetoelectronics is a rapidly developing field of science dealing with spindepen dent transport phenomena [1]. Studies of charge car rier transport in magnetic (and especially dilute) semi conductors have become one of the most intensely developing trends in solid state physics in connection with designing spintronics devices [2–5]. Apart from their possible applications, magnetic semiconductors are of independent interest for fundamental physics studies. Dilute magnetic semiconductors contain only a few percent of magnetic impurities, so that direct exchange interaction between impurity atoms is negli gibly weak. However, ferromagnetism induced by free holes was discovered in dilute magnetic semiconduc tors. To describe the ferromagnetic state in these mate rials, indirect exchange models have been developed (see, for example, [6]), and considerable advances have been made in this direction [2, 6, 7]. Some aspects (in particular, the effect of inhomogeneities in the distribution of magnetic ions on the magnetic and transport properties of samples) remain unclear and call for further investigations [2]. Analysis of spin dependent transport of charge carriers, which reflects the mutual effect of transport and magnetic proper ties, is important for determining the features of the ferromagnetic state in dilute magnetic semiconduc tors.
A large number of publications are devoted to anal ysis of the transport properties of dilute magnetic semiconductors; however, the number of works in which 2D systems with magnetic impurities are ana lyzed is much smaller than the number of works devoted to 3D semiconductors. By way of example, we can mention h
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