Pressure-Induced Hydrogen-Hydrogen Interaction in Metallic FeH Revealed by NMR

Meier, Thomas; Trybel, Florian; Khandarkhaeva, Saiana; Steinle‐Neumann, Gerd; Chariton, Stella; Fedotenko, Timofey; Petitgirard, Sylvain; Hanfland, Michael; Glazyrin, Konstantin; Dubrovinskaia, Natalia; Dubrovinsky, Leonid

doi:10.1103/physrevx.9.031008

Cited by 30 publications

(55 citation statements)

References 48 publications

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“…Intense 1 H-NMR signals were recorded at frequencies of 45.26 MHz, corresponding to an external magnetic field strength of about 1063 mT. Using nutation experiments, we found optimal excitation pulses between 1 and 1.2 µs for both cells, in reasonable agreement with earlier experiments 28 – 30 , 34 .…”

Section: Methodssupporting

confidence: 87%

“…The diamond anvils were coated with a 1-µm-thick layer of copper using physical vapour deposition 28 . Double 29 (in the case of the 250 µm diamonds) and triple 30 (for the 100 µm diamonds) stage Lenz-lens radio-frequency resonators were produced by using focused ion beam milling. To ensure electrical insulation and avoid hydrogen diffusion into the rhenium, the gaskets were coated by 500-nm-thick layers of Al 2 O 3 .…”

Section: Methodsmentioning

confidence: 99%

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Nuclear spin coupling crossover in dense molecular hydrogen

et al. 2020

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One of the most striking properties of molecular hydrogen is the coupling between molecular rotational properties and nuclear spin orientations, giving rise to the spin isomers ortho- and para-hydrogen. At high pressure, as intermolecular interactions increase significantly, the free rotation of H2 molecules is increasingly hindered, and consequently a modification of the coupling between molecular rotational properties and the nuclear spin system can be anticipated. To date, high-pressure experimental methods have not been able to observe nuclear spin states at pressures approaching 100 GPa (Meier, Annu. Rep. NMR Spectrosc. 94:1–74, 2017; Meier, Prog. Nucl. Magn. Reson. Spectrosc. 106–107:26–36, 2018) and consequently the effect of high pressure on the nuclear spin statistics could not be directly measured. Here, we present in-situ high-pressure nuclear magnetic resonance data on molecular hydrogen in its hexagonal phase I up to 123 GPa at room temperature. While our measurements confirm the presence of ortho-hydrogen at low pressures, above 70 GPa, we observe a crossover in the nuclear spin statistics from a spin-1 quadrupolar to a spin-1/2 dipolar system, evidencing the loss of spin isomer distinction. These observations represent a unique case of a nuclear spin crossover phenomenon in quantum solids.

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Section: Methodssupporting

confidence: 87%

Section: Methodsmentioning

confidence: 99%

Nuclear spin coupling crossover in dense molecular hydrogen

et al. 2020

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“…studied B 10 H 14 [402] and its transformation under pressure. Other systems studied for their potential transformation to a metallic substance include: He-H [403], Li-H [404], Na-H [405], H-O [406,407], AlH 3 [408], Fe-H [409,410,411,412,413] [428]. These systems were subject to pressure and phase transformation occurred, but no clear evidence of either metallicity or superconductivity was given, and transport measurements are not reported.…”

Section: Non-superconducting Hydridesmentioning

confidence: 99%

A perspective on conventional high-temperature superconductors at high pressure: Methods and materials

et al. 2020

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Two hydrogen-rich materials: H 3 S and LaH 10 , synthesized at megabar pressures have revolutionized the field of superconductivity by providing a first glimpse into the solution for the hundred-year-old problem of room-temperature superconductivity. The mechanism governing these exceptional superconductors is the conventional electron-phonon coupling. Here, we describe recent advances in experimental techniques, superconductivity theory and first-principles computational methods, which made this discovery possible. The aim of this work is to provide an up-to-date compendium of the available results on superconducting hydrides and explain the synergy of different methodologies that led to the extraordinary discoveries in the field. Furthermore, in an attempt to evidence empirical rules governing superconductivity in binary hydrides under pressure, we discuss general trends in electronic structure and chemical bonding. The last part of the Review introduces possible strategies to optimize pressure and transition temperatures in conventional superconducting materials. Directions for future research in areas of theory, computational methods and high-pressure experiments are proposed, in order to advance our understanding of superconductivity.

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“…Experiments are challenging due to a variety of factors, including weak signals, low resonator sensitivities, and poor access to the samples in the anvil cells, which have traditionally limited high pressure NMR spectroscopy experiments to a maximum of a few tens of GPa [15]. This situation has recently changed with the ground-breaking developments of Meier and co-workers, who exploiting magnetic flux tailoring Lenz lenses to amplify the magnetic field at the sample have measured hydrogen NMR spectra of paraffin up to 72 GPa [16] and of FeH up to 200 GPa [17]. The state-of-the-art of high pressure NMR spectroscopy has recently been reviewed in Refs.…”

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confidence: 99%

Nuclear Magnetic Resonance Spectroscopy as a Dynamical Structural Probe of Hydrogen under High Pressure

2019

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An unambiguous crystallographic structure solution for the observed phases II-VI of high pressure hydrogen does not exist due to the failure of standard structural probes at extreme pressure. In this work we propose that nuclear magnetic resonance spectroscopy provides a complementary structural probe for high pressure hydrogen. We show that the best structural models available for phases II, III, and IV of high pressure hydrogen exhibit markedly distinct nuclear magnetic resonance spectra which could therefore be used to discriminate amongst them. As an example, we demonstrate how nuclear magnetic resonance spectroscopy could be used to establish whether phase III exhibits polymorphism. Our calculations also reveal a strong renormalisation of the nuclear magnetic resonance response in hydrogen arising from quantum fluctuations, as well as a strong isotope effect. As the experimental techniques develop, nuclear magnetic resonance spectroscopy can be expected to become a useful complementary structural probe in high pressure experiments.

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Pressure-Induced Hydrogen-Hydrogen Interaction in Metallic FeH Revealed by NMR

Cited by 30 publications

References 48 publications

Nuclear spin coupling crossover in dense molecular hydrogen

Nuclear spin coupling crossover in dense molecular hydrogen

A perspective on conventional high-temperature superconductors at high pressure: Methods and materials

Nuclear Magnetic Resonance Spectroscopy as a Dynamical Structural Probe of Hydrogen under High Pressure

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