Isotope effect in the superconducting palladium-hydrogen-deuterium system

Skośkiewicz, T.; Szafrański, A. W.; Bujnowski, Waclaw; Baranowski, B.

doi:10.1088/0022-3719/7/15/015

Cited by 78 publications

(19 citation statements)

References 20 publications

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“…The completly unexpected discovery of superconductivity with relativly high transition temperature of about 9K in PdH x [22] by prof. Tadeusz Skośkiewicz in 1972 and shortly after that the negative isotope effect [23] by the same author gave new impetus to the field. The other great Polish discovery of the time, namely the coexistence of superconductivity and ferromagnetism in Y 9 Co 7 (or Y 4 Co 3 ) by prof. Andrzej Ko lodziejczyk [24] remained virtually unnoticed.…”

Section: Fig 3: the Original Plotmentioning

confidence: 97%

Remarks on the First Hundred Years of Superconductivity

Wysokiński

2012

Acta Phys. Pol. A

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On the occasion of centenary of superconductivity discovery I recall some facts from the rst period and attempts to understand the phenomenon. It turns out that most famous physicists of the rst half of XX century have tried to solve the puzzle. Bardeen, Cooper and Schrieer succeeded in 1957. The BCS theory successfully described all known facts and oered new predictions, which soon have been conrmed experimentally contributing to the widespread acceptance of the theory. It have found applications in nuclear physics, theory of neutron stars and cold atomic gases

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Section: Fig 3: the Original Plotmentioning

confidence: 97%

Remarks on the First Hundred Years of Superconductivity

Wysokiński

2012

Acta Phys. Pol. A

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“…Despite significant effort, only two families of relatively high T c materials have been found with Th [31] and Pd [7,32] hydrides. Both systems showed anomalous isotope effect when doped with deuterium; ThH(D) 3.64 did not show any isotope effect, which initially raised doubts regarding the phonon-mediated mechanism, and PdH(D) showed inverse isotope effect [9]. In the theoretical and experimental papers that followed discovery of PdH superconductor, the anomalous isotope effect was understood as resulting from anomalously large anharmonicity of hydrogen (deuterium) vibrations [33,34,[35][36][37].…”

Section: Electron-phonon Coupling and Anharmonic Effectsmentioning

confidence: 99%

“…The highest T c 's observed in hydrides of Pd and Pd-Au, Pd-Cu alloys did not exceed temperatures of the order of 15-17 K [7,8]. Moreover, substantial inverse isotope effect was observed in PdH and PdD, at first raising doubts in the validity of the electron-phonon coupling mechanism for superconductivity in these materials, and later leading to the understanding of the role played by anharmonicity of hydrogen vibrations in such ''simple'' hydrides [9]. It should be noted that there are published claims of nearly room-temperature superconductivity in PdH x materials [10], which have not been confirmed by other experimentalists and have no theoretical backing at the moment.…”

Section: Introductionmentioning

confidence: 98%

Superconductivity in compressed hydrogen-rich materials: Pressing on hydrogen

Struzhkin

2015

Physica C: Superconductivity and its Applications

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a b s t r a c tPeriodic table of elements starts with hydrogen, a simplest element of all. The simplicity is lost when the element is compressed to high densities or participates in a chemical bonding in compounds, being subjected to ''chemical pressure'' of surrounding atoms or molecules. The chemical nature of hydrogen is dictated by its simplest electronic shell, which has only one electron. Hydrogen can donate this electron and behave like alkali metal, or accept an extra electron and form a hydride ion with closed shell resembling a group VII element. The complexity of hydrogen goes beyond these simplest configurations, when hydrogen is involved in a multicenter bonding or in hydrogen bonds. This complex behavior is tightly related to the ability of hydrogen to participate in the process of electronic transport in solids and potentially be able to contribute to the superconductivity in a material. Hydrogen by itself when compressed to immense pressures of 400-500 GPa may form a simple atomic phase with very high critical superconducting temperatures (T c ) well above room temperature. While this theoretical insight awaits confirmation at pressures at the limit of current experimental capabilities, a variety of other hydrogen-rich materials have been suggested recently to have record high T c values. The very existence of many of these materials still lacks experimental confirmation. In this review article, we will present an extensive list of such predicted materials. We will also review superconductivity in classical hydrides (mostly metal hydrides) and current theoretical understanding of relatively low T c 's in metal hydrides of transition and noble metals.

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“…Here we consider the hydride system with a very unusual isotope effect, the PdH(D) system. Quite an amount of theoretical and experimental work [11,12,5,13,14,15,16,17,18,6,19,20,21,22,23,10] has been done since the discovery of the inverse isotope effect in PdH(D) (α ≈ −0.3) without reaching to a satisfactory explanation of this phenomenon. Most of the mechanism that have been proposed to explain it attribute the inverse isotope effect to vibrational effects of Hydrogen and Deuterium, such as anharmonicity [19,20,10] or to the zero-point motion [21], both of which have an effect the electron-phonon coupling.…”

Section: Introductionmentioning

confidence: 99%

On the calculation of the inverse isotope effect in PdH(D): A Migdal-Eliashberg theory approach

Villa-Cortés

Baquero

2018

Journal of Physics and Chemistry of Solids

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Replacement of hydrogen by deuterium in palladium hydride results in higher superconducting temperatures and an anomalous isotope effect that has not been yet fully explained. In this work, we try a new approach to the explanation of the inverse isotope effect in PdH(D). Our approach introduces two new aspects. First, we took into account the experimental evidence that at temperatures below 50 K, the crystal structure of PdH and of PdD is zincblende. Second, we take into account not only the influence of the electron-phonon interaction but also the electron-electron interaction contribution to the isotope coeffiecient due tothe replacement of deuterium in the place of hydrogen. We used the Migdal-Eliashberg theory to perform our ab initio calculations. We found in this picture that the electron-electron interaction is considerably reduced by the isotope substitution and is the most important factor to explain the inverse isotope effect. We found ∆T total c = 2.224 K and α = −0.3134 in excellent agreement with the values found experimentally.On the Calculation of the Inverse Isotope Effect in PdH(D)

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Isotope effect in the superconducting palladium-hydrogen-deuterium system

Cited by 78 publications

References 20 publications

Remarks on the First Hundred Years of Superconductivity

Remarks on the First Hundred Years of Superconductivity

Superconductivity in compressed hydrogen-rich materials: Pressing on hydrogen

On the calculation of the inverse isotope effect in PdH(D): A Migdal-Eliashberg theory approach

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