Experimental determination of phonon thermal conductivity and Lorenz ratio of single crystal metals: Al, Cu, and Zn

Yao, Meng; Zebarjadi, Mona; Opeil, Cyril

doi:10.1063/1.4997034

Cited by 26 publications

(18 citation statements)

References 36 publications

(25 reference statements)

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“…This unequal importance of vertical events for electrical and thermal conductivities, pulls down the L(T )/L 0 ratio at finite temperature and generates a finite-temperature breakdown of the Wiedemann-Franz law [1]. Such a behavior was observed in highpurity Cu half a century ago [2], in other elements, such as Al and Zn [3], in heavy-fermion metals such as UPt 3 [5], CeRhIn 5 [4] or CeCoIn 5 [7] as well as in magnetically-ordered elements like Ni [20] or Co [21].…”

Section: Resultsmentioning

confidence: 99%

“…At intermediate temperatures, inelastic scattering is known to degrade thermal current more efficiently than the electrical current [1]. Experiments have found a zero-temperature validity combined to a downward departure in elemental metals (due to electron-phonon scattering) [2,3] as well as in correlated metals (because of electron-electron arXiv:1806.04094v3 [cond-mat.str-el] 17 Dec 2018 scattering) [4,5]. During the past decade, the search for a possible breakdown of the WF law near a quantum critical point [6] motivated high-resolution experiments, which verified its zero-temperature validity within experimental margin and quantified the deviation at finite temperature [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Departure from the Wiedemann–Franz law in WP2 driven by mismatch in T-square resistivity prefactors

et al. 2018

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The Wiedemann-Franz (WF) law establishes a link between heat and charge transport due to electrons in solids. The extent of its validity in presence of inelastic scattering is a question raised in different contexts. We report on a study of the electrical, σ, and thermal, κ, conductivities in WP2 single crystals. The WF holds at 2 K, but a downward deviation rapidly emerges upon warming. At 13 K, there is an exceptionally large mismatch between Lorenz number and the Sommerfeld value.We show that this is driven by a fivefold discrepancy between the T -square prefactors of electrical and thermal resistivities, both caused by electron-electron scattering. This implies the existence of abundant small-scattering-angle collisions between electrons, due to strong screening. By quantifying the relative frequency of collisions conserving momentum flux, but degrading heat flux, we identify a narrow temperature window where the hierarchy of scattering times may correspond to the hydrodynamic regime.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Departure from the Wiedemann–Franz law in WP2 driven by mismatch in T-square resistivity prefactors

et al. 2018

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“…All of the thermostatting scenarios in our work except the electron-phonon coupled ones are difficult to reproduce in an experiment, as it is not trivial to suppress electronic heat conduction. 66,67 While one could simply conduct nanomachining trials at higher temperatures, any influence of excessive thermal gradients would still be lost. That said, it may be possible to verify the time-development of the near-surface structural changes occurring in a nanocrystalline sample due to abrasive nanomachining.…”

Section: Discussionmentioning

confidence: 99%

Thermostat Influence on the Structural Development and Material Removal during Abrasion of Nanocrystalline Ferrite

Eder

Cihak-Bayr

Bianchi

et al. 2017

ACS Appl. Mater. Interfaces

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We consider a nanomachining process of hard, abrasive particles grinding on the rough surface of a polycrystalline ferritic work piece. Using extensive largescale molecular dynamics (MD) simulations, we show that the mode of thermostatting, i.e., the way that the heat generated through deformation and friction is removed from the system, has crucial impact on tribological and materials related phenomena. By adopting an electron-phonon coupling approach to parametrize the thermostat of the system, thus including the electronic contribution to the thermal conductivity of iron, we can reproduce the experimentally measured values that yield realistic temperature gradients in the work piece. We compare these results to those obtained by assuming the two extreme cases of only phononic heat conduction and instantaneous removal of the heat generated in the machining interface. Our discussion of the differences between these three cases reveals that although the average shear stress is virtually temperature independent up to a normal pressure of approximately 1 GPa, the grain and chip morphology as well as most relevant quantities depend heavily on the mode of thermostatting beyond a normal pressure of 0.4 GPa. These pronounced differences can be explained by the thermally activated processes that guide the reaction of the Fe lattice to the external mechanical and thermal loads caused by nanomachining.

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“…Note that for the phonon and electronic band structure calculations of these GM structures, we have also applied Van der We also investigated the lattice thermal properties since the CENT potential can give a good and reliable description of the third-order IFCs. Although in high purity metals, the electronic part of the thermal conductivity dominates [71], we expect that due to the small amount of electrons which lie above the pseudo gap in the GM structures, the lattice thermal conductivity should be important for these structures.…”

Section: B Structures and Properties Of Non-stoichiometric Polymorphsmentioning

confidence: 99%

Large Scale Structure Prediction of Near-Stoichiometric Magnesium Oxide Based on a Machine-Learned Interatomic Potential: Novel Crystalline Phases and Oxygen-Vacancy Ordering

Tahmasbi,

Goedecker,

Ghasemi

2021

Preprint

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Using a fast and accurate neural network potential we are able to systematically explore the energy landscape of large unit cells of bulk magnesium oxide with the minima hopping method. The potential is trained with a focus on the near-stoichiometric compositions, in particular on suboxides, i.e., Mg x O 1−x with 0.50 < x < 0.60. Our extensive exploration demonstrates that for bulk stoichiometric compounds, there are several new lowenergy rocksalt-like structures in which Mg atoms are octahedrally six-coordinated and form trigonal prismatic motifs with different stacking sequences. Furthermore, we find a dense spectrum of novel non-stoichiometric crystal phases of Mg x O 1−x for each composition of x. These structures are mostly similar to the rock salt structure with octahedral coordination and five-coordinated Mg atoms. Due to the removal of one oxygen atom, the energy landscape becomes more glass-like with oxygen-vacancy type structures that all lie very close to each other energetically. For the same number of magnesium and oxygen atoms our oxygen-deficient structures are lower in energy if the vacancies are aligned along lines or planes than rock salt structures with randomly distributed oxygen vacancies. We also found the putative global minima configurations for each composition of the non-stoichiometric suboxide structures. These structures are predominantly composed of (111) slabs of the rock salt structure which are terminated with Mg atoms at the top and bottom, and are stacked in different sequences along the z-direction. Like other Magnéli-type phases, these structures have properties that differ considerably from their stoichiometric counterparts such as low lattice thermal conductivity and high electrical conductivity.

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Experimental determination of phonon thermal conductivity and Lorenz ratio of single crystal metals: Al, Cu, and Zn

Cited by 26 publications

References 36 publications

Departure from the Wiedemann–Franz law in WP2 driven by mismatch in T-square resistivity prefactors

Departure from the Wiedemann–Franz law in WP2 driven by mismatch in T-square resistivity prefactors

Thermostat Influence on the Structural Development and Material Removal during Abrasion of Nanocrystalline Ferrite

Large Scale Structure Prediction of Near-Stoichiometric Magnesium Oxide Based on a Machine-Learned Interatomic Potential: Novel Crystalline Phases and Oxygen-Vacancy Ordering

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