AVS 52nd International Symposium
    Magnetic Interfaces and Nanostructures Wednesday Sessions
       Session MI+EM-WeA

Paper MI+EM-WeA9
Effects of Differing Mn@sub Ga@/Mn@sub I@ on the Anomalous Hall Effect in (Ga,Mn)As

Wednesday, November 2, 2005, 4:40 pm, Room 204

Session: Magnetic Semiconductors
Presenter: Y.D. Park, Seoul National University, Korea
Authors: Y.S. Kim, Seoul National University, Korea
H.K. Choi, Seoul National University, Korea
Z.G. Khim, Seoul National University, Korea
S.H. Chun, Sejong University, Korea
Y.D. Park, Seoul National University, Korea
Correspondent: Click to Email
We report on the effect of differing ratios of substitutional and interstitial Manganese (Mn@sub Ga@/Mn@sub I@) on the Anomalous Hall Effect(AHE) in low temperature molecular beam epitaxy prepared (Ga,Mn)As diluted magnetic semiconductors. As-grown (Ga,Mn)As epifilms with Mn content from 2.4 % ~ 6.1 % exhibit ferromagnetic ordering below temperatures ranging from 60 to 110 K. Relatively differing Mn@sub Ga@/Mn@sub I@ ratios were achieved by careful annealing at moderate temperatures as evident in the differing resistivities (as low as 2.5 m@ohm@-cm)/ Hall carrier concentrations (as high as ~ 8 x 10@super 20@cm@super -3@) as well as T@sub C@ (as high as 150 K) with optimal annealing temperature found to be 250°C.@footnote 1@ AC-magnetotransport measurements conducted from 5 K to 300 K and with applied magnetic fields ranging to +/- 7 Tesla indicate similar field dependence of resistivity, AHE, and metal-insulator-like transition near T@sub C@ as reported by others.@footnote 2@ T@sub C@'s as found from Arrott plots from the resulting AHE measurements agree well with direct SQUID magnetometry measurements. Log-log plots of @rho@@sub xy@, d@rho@@sub xy@ /dH, and @rho@@sub xy@/M@sub S@ vs. @rho@@sub xx@, cumulated from AHE measurements at temperatures below T@sub C@ of differing as-grown Mn content and annealing conditions, indicate skew scattering to be the dominant mechanisms for AHE in (Ga,Mn)As regardless of as-grown Mn content or Mn@sub Ga@/Mn@sub I@ ratios and possibly regardless of presence of non-magnetic or magnetic Mn-rich nano-clusters. We will also discuss the results in light of theory@footnote 3@ of AHE in clean (Ga,Mn)As and experimental reports@footnote 4@ of AHE in DMS systems with ferromagnetic nano-clusters. @FootnoteText@ @footnote 1@T Hayashi et al. APL 78, 1691 (2001); KC Ku et al., APL 82, 2302 (2003).@footnote 2@M Tanaka, JVST B 16, 2267 (1998).@footnote 3@T Jungwirth et al., PRL 88, 207208 (2002).@footnote 4@SR Shinde et al., PRL 92, 166601 (2004).