Title :
Magnetic Anisotropy, Spin Pinning, and Exchange Constants of (Ga,Mn)As Films
Author :
Zhou, Ying-Yuan ; Cho, Yong-Jin ; Ge, Zhiguo ; Liu, Xinyu ; Dobrowolska, Malgorzata ; Furdyna, Jacek K.
Author_Institution :
Dept. of Phys., Notre Dame Univ., IN
fDate :
6/1/2007 12:00:00 AM
Abstract :
In this paper, we present a detailed investigation of exchange-dominated nonpropagating spin-wave modes in a series of 100-nm Ga1-xMnxAs films with Mn concentrations x ranging from 0.02 to 0.08. The angular and Mn concentration dependences of spin-wave resonance (SWR) modes have been studied for both as-grown and annealed samples. Our results indicate that the magnetic anisotropy terms of Ga1-xMnxAs depend on the Mn concentration x, but are also strongly affected by sample growth conditions; moreover, the magnetic anisotropy of Ga1-xMnxAs films is found to be clearly linked to the Curie temperature. The SWR spectra consist of a series of well-resolved standing spin-wave modes. The observed mode patterns are consistent with the Portis volume-inhomogeneity model, in which a spatially nonuniform anisotropy field acts on the Mn spins. The analysis of these exchange-dominated spin-wave modes, including their angular dependences, allows us to establish the exchange stiffness constants for Ga1-xMnx As films
Keywords :
Curie temperature; III-V semiconductors; exchange interactions (electron); ferromagnetic materials; ferromagnetic resonance; gallium arsenide; magnetic anisotropy; magnetic thin films; manganese compounds; semiconductor thin films; semimagnetic semiconductors; spin dynamics; (Ga,Mn)As films; Curie temperature; Ga1-xMnxAs; angular dependence; exchange stiffness constants; magnetic anisotropy; spin pinning; spin wave resonance modes; Annealing; Gallium arsenide; Geometry; Magnetic anisotropy; Magnetic field measurement; Magnetic films; Magnetic resonance; Molecular beam epitaxial growth; Substrates; Temperature; exchange stiffness constant; ferromagnetic semiconductors; magnetic anisotropy; magnons; spin waves;
Journal_Title :
Magnetics, IEEE Transactions on
DOI :
10.1109/TMAG.2007.893316
