Magnetization reversal in europium sulfide nanocrystals

Redígolo, Marcela L.; Koktysh, Dmitry S.; Rosenthal, Sandra J.; Dickerson, James H.; Gai, Zheng; Gao, Lan; Shen, Jian

doi:10.1063/1.2396915

Cited by 21 publications

(23 citation statements)

References 23 publications

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“…Our focus is dominantly on europium sulfide, however, we refer to relevant studies of EuO and EuSe. We have emphasized results from our laboratory, but there are several groups that have made significant contributions to this field [32][33][34][35]. These studies also build on a large body of literature of bulk europium chalcogenide materials which were investigated for 'magnetic bubble' memory devices in the 1960s [17].…”

Section: Introductionmentioning

confidence: 95%

Europium chalcogenide magnetic semiconductor nanostructures

Boncher

Dalafu

Rosa

et al. 2015

Coordination Chemistry Reviews

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Section: Introductionmentioning

confidence: 95%

Europium chalcogenide magnetic semiconductor nanostructures

Boncher

Dalafu

Rosa

et al. 2015

Coordination Chemistry Reviews

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“…[62] Nanocrystalline EuS has been the subject of ongoing experimental and theoretical investigation because of its interesting magnetic properties. [63][64][65] EuS exhibits ferromagnetic behavior with a Curie temperature of 16 K and is a candidate model system for demonstrating spintronics or optoelectronic phenomena. It is also an example of a bulk semiconductor material that displays a distinct absorption band, found at $2.35 eV, Figure 3.…”

Section: Interesting Band Structure Effects In Bulk Nanocrystalsmentioning

confidence: 99%

Controlling the Optical Properties of Inorganic Nanoparticles

Scholes¹

2008

Adv Funct Materials

230

198

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The sophistication with which we can now prepare and characterize inorganic nanoparticles has inspired new areas of research into the fundamental properties and applications of these fascinating nanoscale systems. In this article some of the recent ideas concerning control of their optical properties are examined and explained, focusing on semiconductor nanocrystals. It is known that the optical properties of nanocrystals can be size‐tunable, but it is less obvious how shape matters. To explain how size as well as shape matters, the electronic structure of nanocrystals is sketched in relatively simple terms, leading to an introduction to deeper concepts at the heart of spectroscopy such as the exciton fine structure. The exciton fine structure states, although obscured by inhomogeneous line broadening, dictate selection rules for optical excitation. These viewpoints are compared and contrasted to well‐established principles in molecular spectroscopy that provide inspiration as well as perspective. The control of optical poperties is founded on our ability to prepare good quality colloidal particles. Recent advances in nanocrystal shape control are described. The current status of heterostructures is examined, with an emphasis on charge separation in CdSe–CdTe nanorods.

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“…Since the magnetic properties of EuS are governed by the strongly bound 4f orbital, changes in the atomic arrangement thus leads to modified orbital overlaps between nearest neighbor lattice sites and next-nearest neighbor sites. Consequently, size-dependent optical, magnetic [1,2], and structural characteristics can been observed.Aberration-corrected STEM analysis revealed the presence of highly crystalline face-centered cubic nanoparticles with dimensions well below 2 nm. Figure 1 shows an annular dark field STEM micrograph with nanocrystals of various sizes within the quantim-confined region.…”

mentioning

confidence: 94%

mentioning

confidence: 94%

Characterization of EuS Nanotubes in Quantum Confinement

et al. 2009

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Europium monochalcogenides of the form EuX (X = O, S, Se, Te) have fascinating optical, magneto optical and magnetic properties. For face-centered cubic EuS, increased Curie temperatures and reversal in the remanent magnetization were observed with decreasing particles sizes, ultimately leading to quantum confinement structures.EuS nanoparticles were synthesized by thermolysis of a molecular single source precursor. Dependent on the synthesis parameters, particles sizes ranging either between 2.0 nm and 10.0 nm (nanocrystalline region) or below 2.0 nm (quantum-confined region). With shrinking particle size, surface strain effects can alter the atomic arrangements and therefore the crystal structure. Since the magnetic properties of EuS are governed by the strongly bound 4f orbital, changes in the atomic arrangement thus leads to modified orbital overlaps between nearest neighbor lattice sites and next-nearest neighbor sites. Consequently, size-dependent optical, magnetic [1,2], and structural characteristics can been observed.Aberration-corrected STEM analysis revealed the presence of highly crystalline face-centered cubic nanoparticles with dimensions well below 2 nm. Figure 1 shows an annular dark field STEM micrograph with nanocrystals of various sizes within the quantim-confined region. The detection of isolated Eu atoms dispersed on the carbon support film indicates atomic resolution and single atom sensitivity during the STEM experiments. In many areas of the sample, non-crystalline agglomerates of Eu atoms (likely in conjunction with sulfur atoms) were observed [3].Recently, Harrison et al. synthesized EuS nanotubes with unique optical properties due to unidirectional quantum confinement [4]. SEM, TEM and focused ion-beam microscopy confirmed hollow nanotube morphologies (Figure 2) with wall thickness of the order of 2-5 nm. The rolled-up sheets of EuS were found to be poly-crystalline with grain sizes as small as 10-15 nm. At the time of writing, preliminary data suggest an equilibrium length and diameter of the nanotubes. Furthermore, strain within the sheets seems to cause rupturing of the nanotubes for stress relaxation (cf. Figure 2b). Currently, selected area diffraction and analytical STEM experiments are carried out for more detailed evaluations of atomic and electronic structures as well as local chemistry and oxidation states.

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Magnetization reversal in europium sulfide nanocrystals

Cited by 21 publications

References 23 publications

Europium chalcogenide magnetic semiconductor nanostructures

Europium chalcogenide magnetic semiconductor nanostructures

Controlling the Optical Properties of Inorganic Nanoparticles

Characterization of EuS Nanotubes in Quantum Confinement

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