Magnetization steps of nearest-neighbor exchange interactions in CdS(Co) and CdSe(Co) in fields to 60 Tesla

Foner, S.; Heiman, D.; Vu, T.Q.; Fries, Thomas; McCabe, G. H.; Shapira, Y.; Demianiuk, M.

doi:10.1016/0038-1098(95)00306-1

Cited by 11 publications

(3 citation statements)

References 15 publications

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“…Examples are the determinations of J 1 in Cd 1Ϫx Co x S and Cd 1Ϫx Co x Se. 95,96 Because J 1 in these two materials is relatively large ͑about Ϫ30 K), only a single MST from J 1 pairs was observed in fields up to 600 kOe. To obtain J 1 from H 1 , a correction for the uniaxial single-ion anisotropy of the Co 2ϩ ion, and a second correction for the DN shift ⌬ 1 , were applied before using Eq.…”

Section: B Weak Anisotropiesmentioning

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: B Weak Anisotropiesmentioning

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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“…The exchange constants J in 1 and J out 1 associated to the two groups of nearest neighors (in and out) are different. Both constants have been measured for Cd 1−x Mn x S(e) [24,25], Zn 1−x Mn x O [2], Cd 1−x Co x S(e) [26] and in bulk Zn 1−x Co x O [3]. For the last material, the average with a huge 80 % difference between the two J 1 values.…”

Section: Magnetization Results and Discussionmentioning

confidence: 99%

Magnetization of Zn1-xCoxO nanoparticles: single-ion anisotropy and spin clustering

Gratens¹,

Silva²,

Bernardi³

et al. 2022

Preprint

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“…Foner et al [44] then only give average J : −30.6 ± 1.7 K and −31.0 ± 2 K for CdS and CdSe, respectively. Consequently, J 1 and J 2 constants for these two compounds are not known with precision but should be almost identical in both cases.…”

Section: Co-doped Compoundsmentioning

confidence: 96%

Exchange integrals in Mn- and Co-doped II-VI semiconductors

et al. 2014

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Exchange integrals between nearest-neighbor (NN) transition metal ions in II-VI diluted magnetic semiconductors (DMSs) are calculated within a local superexchange model, which includes orbital-dependent transfer, on-site Coulomb repulsion and Hund's exchange between 3d electrons, and ligand field effects. This extended model gives a quantitative account for the available experimental data on the NN exchange constants in all II-VI DMS family (wurtzite and zinc-blende) doped by cobalt or manganese. As expected, all obtained exchange integrals are antiferromagnetic. Remarkably, the model input parameters are taken directly from the photoemission spectroscopy. We show that in the case of Co-doped compounds, as compared to Mn-doped ones, the exchange process has at least two salient features. The first one is that the electron transfer between NN Co 2+ 3d orbitals strongly depends on their symmetry positions in the crystal lattice. The second one is related to a peculiar virtual process, involving empty and occupied Co 2+ 3d orbitals, which leads to an additional ferromagnetic contribution to the exchange constant. We argue that our systematic study of the superexchange opens a pathway toward an understanding of other exchange mechanisms occurring in DMSs.

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Magnetization steps of nearest-neighbor exchange interactions in CdS(Co) and CdSe(Co) in fields to 60 Tesla

Cited by 11 publications

References 15 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

Magnetization of Zn1-xCoxO nanoparticles: single-ion anisotropy and spin clustering

Exchange integrals in Mn- and Co-doped II-VI semiconductors

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