Structural, electrical, and optical properties of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">La</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn><mml:mi>−</mml:mi><mml:mi>z</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">Y</mml:mi></mml:mrow><mml:mrow><mml:mi>z</mml:mi></mml:mrow></mml:msub></mml:mrow><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">H</mml:mi>

Gogh, A.T.M. van; Nagengast, D.; Kooij, Ernst S.; Koeman, N.J.; Rector, J.H.; Griessen, R.; Flipse, C. F. J.; Smeets, R.J.J.G.A.M.

doi:10.1103/physrevb.63.195105

Cited by 105 publications

(90 citation statements)

References 48 publications

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“…% Mg is added as was shown already by Van der Molen et al 16 Thus, both YH x and LaH x stay fcc between xϭ2 and xϭ3 and their optical properties change gradually with hydrogen concentration. 19 Magnesium however, is hcp in the metallic phase and tetragonal ͑rutile͒ 43,44 or orthorhombic 44,45 in the insulating MgH 2 phase. Thus, magnesium forms MgH 2 grains ͑with a structural phase transition͒, whose volume fraction increases with increasing H uptake.…”

Section: Re-mg Filmsmentioning

confidence: 99%

“…1͒. The resistivity data are almost featureless in contrast to RE films without Mg. 19 When the resistivity suddenly increases around tϭ750 s ͑i.e., when the material goes from metallic to insulating͒, the reflection drops rapidly and the black state develops. This points to percolation phenomena in our films.…”

Section: Resistivitymentioning

confidence: 99%

“…Technologically this is a significant improvement upon REH x that exhibits an optical transmission window in the red (1.6рប р2.1 eV) at hydrogen concentrations 1.7рxр2.1 in their reflective state and a transparent state (REH 3Ϫ␦ ) with characteristic colors, e.g., yellow for YH 3Ϫ␦ ͑absorption edge at 2.6 eV͒ and red for LaH 3Ϫ␦ ͑absorption edge at 1.9 eV͒. 19 Apart from a reflecting and a transparent state, these RE-Mg alloys and thin Mg films exhibit also a highly absorbing, black state during loading with hydrogen. This black state has been observed in Gd 1Ϫz Mg z H x with zϾ0.50 ͑Refs.…”

Section: Introductionmentioning

confidence: 99%

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Highly absorbing black Mg and rare-earth-Mg switchable mirrors

2004

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Apart from a reflecting and a transparent state, rare-earth-Mg alloys ͑RE-Mg͒ exhibit also a highly absorbing, black state during loading with hydrogen. The occurrence of such a black state is due to the disproportionation into subwavelength size REH 2ϩ⑀ and Mg grains during the first hydrogen loading. While the optical properties of REH x change continuously with a further increase in hydrogen concentration x, Mg changes abruptly from a good reflector to a transparent insulator (MgH 2 ). Thin pure Mg films also show this black state when ͑un͒loaded carefully at elevated temperatures. By using the Bruggeman effective medium approximation in combination with the transfer matrix method it is shown that the coexistence of Mg and MgH 2 grains is the cause of this high absorption. Furthermore, we compare this phenomenon to the high absorption of light observed in metal-dielectric composites.

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Section: Re-mg Filmsmentioning

confidence: 99%

Section: Resistivitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly absorbing black Mg and rare-earth-Mg switchable mirrors

2004

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“…2 These first-generation hydrogen switchable materials ͑HYSWIM͒ were soon followed by a second generation of HYSWIMs consisting of Mg-alloyed rare-earth-hydrides 3,4 discovered by Van In this letter, we report on another remarkable optical property of Mg 2 NiH x films. We show that already at low hydrogen concentration ͑i.e., for xϽ0.3͒, Mg 2 NiH x films exhibit dramatic changes in reflectance.…”

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Tunable reflectance Mg–Ni–H films

Isidorsson

Giebels

Griessen

et al. 2002

Applied Physics Letters

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Mg 2 NiH x switchable mirrors, which switch from shiny metallic Mg2Ni to transparent Mg2NiH4, are shown to exhibit also dramatic reversible changes in reflectance at remarkably low hydrogen concentrations. Already for x≅0.3 a 232 nm thick Mg2NiHx film has an absorptance of ∼90% over the whole visible optical spectrum. The transition from highly reflective to black occurs in the concentration interval 0.1<x<0.3. The volume changes involved are one order of magnitude smaller than in the transition from reflecting to transparent. This is expected to enhance the lifetime of future devices based on these materials.

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“…A wide range of possible applications follows, from solid state displays to smart windows. A key aspect of the technology is the opening of an optical gap of order 3 eV in the insulator [7] -a Hubbard gap -which arises from pronounced electronelectron interactions [8][9][10].…”

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Quantum Fluctuations and the Closing of the Coulomb Gap in a Correlated Insulator

et al. 2002

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The ''switchable mirror'' yttrium hydride is one of the few strongly correlated systems with a continuous Mott-Hubbard metal-insulator transition. We systematically map out the low temperature electrical transport from deep in the insulator to the quantum critical point using persistent photoconductivity as a drive parameter. Both activated hopping over a Coulomb gap and power-law quantum fluctuations must be included to describe the data. Collapse of the data onto a universal curve within a dynamical scaling framework (with corrections) requires z 6:0 0:5, where and z are the static and dynamical critical exponents, respectively. DOI: 10.1103/PhysRevLett.89.276402 PACS numbers: 71.30.+h, 71.27.+a, 72.20.-i, 73.50.-h The metal-insulator (MI) transition is only defined properly at temperature T 0, where the electrical conductivity is identically zero in the insulator and assumes a finite value in the metal. Nonetheless, experiments at finite temperature can reveal fundamental properties of the transition by probing quantum fluctuations in the immediate vicinity of the T 0 critical point [1]. Quantum fluctuations inextricably link the static and dynamical response [2], and have led to predictions for new exponents and scaling forms [3] for T; n on both sides of the MI transition. Here n is the distance from the quantum critical point for a transition tuned by electron density, pressure, magnetic field, or any such nonthermal means.The T 0 MI transition in the limit of strong electronelectron correlations has remained resistant to both theoretical understanding and experimental characterization. Progress in this direction would be welcome for illuminating the Mott-Hubbard MI transition itself as well as for shedding light on the physics of cuprate superconductors, colossal magnetoresistance perovskites, rare earth actinides, and transition metal oxides. Moreover, systematic studies of the development of correlations and fluctuations in the insulator are sorely lacking when compared to investigations of the metal. We address these shortcomings through a high-resolution study of the insulating state in yttrium hydride as we approach the T 0 MI transition through successive illuminations under ultraviolet light. Unlike most highly correlated materials, YH x does not have a first-order structural phase transition that cuts off the critical behavior. It retains a continuous Mott-Hubbard MI transition, permitting full access to the quantum critical point.Yttrium hydride and lanthanum hydride are the original ''switchable mirrors' ' [4] with remarkable electronic and optical properties [5]. The reversible transition from shiny, metallic dihydride to transparent, insulating trihydride can be triggered at room temperature simply by changing the surrounding hydrogen gas pressure or an electrolytic cell potential [6]. A wide range of possible applications follows, from solid state displays to smart windows. A key aspect of the technology is the opening of an optical gap of order 3 eV in the insulator [7] -a Hubbard gap -...

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Structural, electrical, and optical properties ofLa1−zYzH

Cited by 105 publications

References 48 publications

Highly absorbing black Mg and rare-earth-Mg switchable mirrors

Highly absorbing black Mg and rare-earth-Mg switchable mirrors

Tunable reflectance Mg–Ni–H films

Quantum Fluctuations and the Closing of the Coulomb Gap in a Correlated Insulator

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