Alloy nonrandomness in diluted magnetic semiconductors

Harrison, P.; Fatah, J. M.; Stirner, T.; Hagston, W. E.

doi:10.1063/1.360954

Cited by 8 publications

(6 citation statements)

References 6 publications

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“…Harrison et al 108 questioned the sensitivity of this technique for detecting a nonrandom distribution, using the fcc cation lattice as an example. However, their conclusion is based on invalid approximations.…”

Section: E Nonrandom Distribution Of Magnetic Ions In Bulk Dmssmentioning

confidence: 99%

Magnetization-step studies of antiferromagnetic clusters and single ions: Exchange, anisotropy, and statistics

Shapira

Bindilatti

2002

Journal of Applied Physics

114

141

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Theoretical and numerical model for estimating unknown magnetic parameters in studying ferromagnetic and antiferromagnetic coupled films Influence of exchange energy and magnetic anisotropy on the nanocrystalline alloy A magnetic cluster is a group of magnetic ions ͑''spins''͒ that interact with each other but which, to a good approximation, do not interact with other magnetic ions. Such clusters are responsible for many of the interesting and useful properties of a large number of molecular crystals, and of dilute magnetic materials below the percolation concentration. In a molecular crystal the magnetic clusters are usually all of one type. In a dilute magnetic material, on the other hand, many cluster types are present. The magnetization-step ͑MST͒ method is a relatively new form of spectroscopy for measuring intracluster magnetic interactions, mainly exchange constants and anisotropy parameters. In dilute magnetic materials this method also yields the relative populations of different cluster types. This review focuses on the principles and applications of the MST method to relatively small clusters, no more than a dozen spins or so. It covers only MSTs from spin clusters in which the dominant exchange interaction is antiferromagnetic ͑AF͒, and MSTs from isolated magnetic ions. Such MSTs are the result of changes of the magnetic ground state, caused by energy-level crossings in a magnetic field H. At a sufficiently low temperature, each change of the ground state leads to a MST. Magnetic clusters may be classified by size. The smallest is a ''single,'' consisting of one isolated magnetic ion. Next are ''pairs'' ͑dimers͒, followed by ''triplets'' ͑trimers͒, ''quartets'' ͑tetramers͒, etc. Although the classification by size is useful, clusters of the same size may have different intracluster interactions, and also different geometrical shapes. More detailed classifications of magnetic clusters are therefore also needed. A cluster ''type'' specifies both the size of the cluster and the set of all intracluster magnetic interactions which are nonzero. Different geometries of clusters of the same type correspond to different ''configurations.'' MSTs from isolated spins ͑singles͒ are discussed first. When subjected to certain types of single-ion anisotropy, e.g., uniaxial hard-axis anisotropy, singles give rise to MSTs. Examples of anisotropy parameters which were determined from such MSTs are presented. An interesting application of MSTs from singles is the determination of the populations of Jahn-Teller distortions which are energetically equivalent at Hϭ0 but are inequivalent at finite H. For clusters larger than singles, the strongest intracluster interaction is usually the isotropic exchange. Using a model with one isotropic exchange constant J, predictions for MSTs from pairs, open and closed triplets, and the six possible types of quartets, are presented. Observations of some of these MSTs, and the exchange constants derived from them, are discussed. Recent studies of MSTs from AF rings in molecular crystals ...

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Section: E Nonrandom Distribution Of Magnetic Ions In Bulk Dmssmentioning

confidence: 99%

Magnetization-step studies of antiferromagnetic clusters and single ions: Exchange, anisotropy, and statistics

Shapira

Bindilatti

2002

Journal of Applied Physics

114

141

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“…However, recently we have pointed out some of the possible consequences of a nonrandom distribution of the magnetic ions. 3,9 In particular, we have shown that alloy clustering can give rise to one of several effects which are dependent on the nominal concentration x of the Mn ions. This arises from the fact that, relative to a random distribution, the effect of clustering is to give rise to regions in which x is increased and to other regions where x is decreased.…”

Section: Introductionmentioning

confidence: 96%

Mn ion clustering in II-VI semimagnetic semiconductor heterostructures

et al. 1998

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“…In the case of Zn Mn Se it is [18], [19] eV so the -potential is given by meV (24) As the barrier thickness decreases, interactions among the wells become stronger so the splitting becomes larger. Additionally, the spin splitting is increased because the antiferromagnetic interactions between magnetic ions are reduced which leads to significantly enhanced effective magnetic moments and thepotential [18], [19], [22], [23]. The thickness of magnetic barriers was here set to 1 nm, in the range considered in the literature [18], [19].…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

“…It takes into account the effect of graded interfaces, the interface roughness and the enhanced magnetization at interfaces. Since the parameters used for the characterization of the interface profile are not known for ZnMnSe-ZnCdSe-ZnSe systems, we used a modified model [22], [23] that introduces a 2-monolayer-wide intermixing region left and right of the DMS barrier assuming different Mn concentrations, effective Mn concentrations and effective temperatures in the barriers and the intermixing regions. The complete potential profile of a triple quantum-well structure including the intermixing regions represented by dashed lines is shown in Fig.…”

Section: Theoretical Modelmentioning

confidence: 99%

Dilute magnetic semiconductor quantum-well structures for magnetic field tunable far-infrared/terahertz absorption

Savić

Milanović

Ikonić

et al. 2004

IEEE J. Quantum Electron.

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Article:Savic, I., Milanovic, V., Ikonic, Z. et Abstract-The design of ZnCdSe-ZnMnSe-based quantum wells is considered, in order to obtain a large shift of the peak absorption wavelength in the far infrared range, due to a giant Zeeman splitting with magnetic field, while maintaining a reasonably large value of peak absorption. A triple quantum-well structure with a suitable choice of parameters has been found to satisfy such requirements. A maximal tuning range between 14.6 and 34.7 meV is obtained, when the magnetic field varies from zero to 5 T, so the wavelength of the absorbed radiation decreases from 85.2 to 35.7 m with absorption up to 1.25% at low temperatures. These structures might form the basis for magnetic field tunable photodetectors and quantum cascade lasers in the terahertz range.Index Terms-Infrared detectors, manganese alloys, magnetic field effects, quantum wells, quantum theory, tunable circuits and devices.

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Alloy nonrandomness in diluted magnetic semiconductors

Cited by 8 publications

References 6 publications

Magnetization-step studies of antiferromagnetic clusters and single ions: Exchange, anisotropy, and statistics

Magnetization-step studies of antiferromagnetic clusters and single ions: Exchange, anisotropy, and statistics

Mn ion clustering in II-VI semimagnetic semiconductor heterostructures

Dilute magnetic semiconductor quantum-well structures for magnetic field tunable far-infrared/terahertz absorption

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