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Unformatted text preview: 18 Recently, Man’kov reported the effect of conduction electrons on the magnetization curve of a me- tallic ferromagnet with surface pinning of the magnetic moment following a power-law dependence H ÿ 3/4 to the law of magnetization approach to saturation. 22 In addition, the H ÿ 1/2 dependence in the law approach of the magnetization to saturation holds in bulk samples, where it is due to the point a) Author to whom correspondence should be addressed. Electronic mail: [email protected] 0021-8979/2013/113(17)/17C734/3/$30.00 V C 2013 AIP Publishing LLC 113 , 17C734-1 JOURNAL OF APPLIED PHYSICS 113 , 17C734 (2013) Downloaded 27 May 2013 to 220.127.116.11. This article is copyrighted as indicated in the abstract. Reuse of AIP content is subject to the terms at: http://jap.aip.org/about/rights_and_permissions localization of stresses, and in amorphous ferromagnets with spatial fluctuations of the anisotropy constant, which is strongly dependent on sample thickness. 23 , 24 The AHE has been mainly reported in inhomogeneous magnetic materials, such as magnetic clusters embedded in a semiconductor, or a metal, or an oxide, etc., which is suggested to be associated with spin carrier polar- ization by clusters. Although a number of theoretical models have been proposed to explain the observed effects, no direct ex- perimental evidence has been reported. 7 – 10 In addition, the mag- netic anisotropy of clusters is often randomly distributed in a host matrix (metal, insulator or semiconductor, etc.) that makes difficult to separate intrinsic and extrinsic phenomena. In this work, we present a method that provides direct evidence for spin carrier polarization by clusters by investi- gating the shape of saturated Hall resistance. To analyze this model, we used the in-plane magnetic anisotropy of Fe-Ga and out-of-plane magnetic anisotropy of Fe 3 Ga clusters em- bedded in Fe-Ga hybrid structure. The 1000A ˚ thick Fe 68.3 Ga 31.7 thin films were grown on a semi-insulating GaAs(001) substrate using MBE (molecular beam epitaxy, VG Semicon, Inc.) at 300, 400, and 500 C by coevaporating Fe and Ga, which was monitored by a quartz thickness micro balance. The detailed preparation and growth process of GaAs(001) substrates have been reported else- where. 25 The growth quality of the thin films was monitored by in situ reflection high-energy electron diffraction (RHEED). The surfaces of the films were characterized by atomic force micros- copy (AFM) and field emission scanning electron microscopy (FE-SEM). The crystal structure of the samples was character- ized by X-ray diffraction (XRD). Figures 1(a) – 1(d) show the RHEED patterns of the GaAs(100) wafer and samples grown at 300, 400, and 500 C, respectively. Well defined streaks were observed for the films grown at 300 and 400 C, indicating that the films are the epitax- ially grown and have smooth surface morphologies, as shown in Figs. 1(b) and 1(c) . The change from the streaks to spotty pat- tern was observed for films grown at 500...
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- Fall '13
- Magnetism, Magnetic Field, Magnetic moment, Magnetic anisotropy, out-of-plane magnetic anisotropy, in-plane magnetic anisotropy