AVS 53rd International Symposium
    Electronic Materials and Processing Wednesday Sessions
       Session EM+MI-WeA

Paper EM+MI-WeA8
Detection of Nanometer-Sized Inclusions in Annealed Ga@sub 1-x@Mn@sub x@As from Atypical Scaling Behavior of the Anomalous Hall Coefficient

Wednesday, November 15, 2006, 4:20 pm, Room 2003

Session: Magnetic Semiconductors
Presenter: H.K. Choi, Seoul National University, Korea
Authors: H.K. Choi, Seoul National University, Korea
S.S.A. Seo, Seoul National University, Korea
W.O. Lee, Seoul National University, Korea
Y.S. Oh, Seoul National University, Korea
K.H. Kim, Seoul National University, Korea
T.W. Noh, Seoul National University, Korea
Y.D. Park, Seoul National University, Korea
Correspondent: Click to Email
We report on the anomalous Hall coefficient (R@sub s@) and longitudinal resistivity (@rho@@sub xx@) scaling relationship (R@sub s@=c@rho@@sub xx@@super n@ ) on three series of annealed LT-MBE Ga@sub 1-x@Mn@sub x@As epilayers (x ~ 0.55). After growth, Mn@sub Ga@ were varied by low temperature annealing from 200°-350°C. Our report of the scaling relationship can provide new methods to detect metallic secondary phases could not be observed in HRXRD and SQUID magnetometer. As-grown samples exhibit scaling parameter n of 1, which can be attributed to extrinsic skew scattering origins of the anomalous Hall Effect@footnote 1@ or to AHE attributed to phonon-assisted hopping between localized states in the impurity band.@footnote 2@ For annealing temperatures near the optimal (~ 250°C), we find n ~ 2 to be consistent with recent theories on the intrinsic origins of AHE in Ga@sub 1-x@Mn@sub x@As.@footnote 3@ For annealing temperatures above the optimum, we note n > 3, which atypical behavior cannot be explained in terms of AHE from a DMS system. This atypical behavior is similar to nanometer-sized super-paramagnetic particles in a paramagnetic matrix such as CoAg granular systems.@footnote 4@ This observation from AHE measurements agree well with optical spectroscopy measurements with observed characteristic features attributable to spherical resonance from metallic inclusions.@footnote 5@ @FootnoteText@ @footnote 1@ J. Smit, Physica (Ultrecht) 21, 877 (1955).@footnote 2@ A. A. Burkov and L. Balents, PRL 91, 057202 (2003).@footnote 3@ T. Jungwirth, Q. Niu, and A. H. MacDonald, PRL 88, 207208 (2002).@footnote 4@ Peng Xiong et al., PRL 69 (22), 3220 (1992).@footnote 5@ S.S.A. Seo et al., APL 82, 4749 (2003); S.S.A. Seo et al., JAP 95, 8172 (2004).