Thermal conductivity of solid<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="normal">N</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>-Ar alloys

Ln, Yadon; Ci, Nicholls; Dg, Haase

doi:10.1103/physrevb.40.5215

Cited by 10 publications

(7 citation statements)

References 9 publications

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“…Reconciliation of our results with the experiment in Ref. [19,20] stems from the fact that pairs of N 2 molecules do produce symmetric TLSs in the ArN 2 system [23]. Calculation -KBr:CN is perhaps the most studied disordered lattice showing universal characteristics.…”

supporting

confidence: 84%

“…[12], that CN flips comprise the relevant low energy TLSs [21,22]. However, for long, advance in this direction was hindered because of experiments showing that the substitution of the symmetric N 2 molecules for the asymmetric CO molecules in N 2 /Ar/CO does not change its universal characteristics [19,20]. Our results here, in conjunction with the theory in Ref.…”

supporting

confidence: 62%

“…Note, that although we focus here on the simplest single impurity excitations, our analysis does not exclude the possibility of symmetric and asymmetric multi-impurity excitations [16][17][18]. Such excitations are expected to be significant especially for systems where single impurity excitations do not produce symmetric TLSs [19,20].…”

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confidence: 99%

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Identification of Strong and Weak Interacting Two-Level Systems in KBr:CN

Gaita‐Ariño¹,

Schechter²

2011

Phys. Rev. Lett.

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Tunneling two-level systems (TLSs) are believed to be the source of phenomena such as the universal low temperature properties in disordered and amorphous solids, and 1/f noise. The existence of these phenomena in a large variety of dissimilar physical systems testifies for the universal nature of the TLSs, which however, is not yet known. Following a recent suggestion that attributes the low temperature TLSs to inversion pairs [M. Schechter and P. C. E. Stamp, arXiv:0910.1283.] we calculate explicitly the TLS-phonon coupling of inversion symmetric and asymmetric TLSs in a given disordered crystal. Our work (a) estimates parameters that support the theory in M. Schechter and P. C. E. Stamp, arXiv:0910.1283, in its general form, and (b) positively identifies, for the first time, the relevant TLSs in a given system.

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supporting

confidence: 84%

supporting

confidence: 62%

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Identification of Strong and Weak Interacting Two-Level Systems in KBr:CN

Gaita‐Ariño¹,

Schechter²

2011

Phys. Rev. Lett.

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“…Although we have not checked all types of excitations, including those involving larger number of impurities, we can not foresee a scenario in which any such type of excitation would give rise to a systematically weak interaction with the strain. Indeed, although excess low temperature specific heat is found in Ar:N 2 , resulting from an abundance of low energy excitations, its thermal conductivity was found to have a very different temperature dependence than that typical for glasses at low temperatures [20]. We therefore argue that Ar:N 2 is a non-universal glass, the first among strongly disordered systems having tunneling states, whereas the apparent similarity between the values of the specific heat in Ar:N 2 and Ar:N 2 :CO [19] is limited to the relatively high temperature, in comparison to the energy scale of the bias energies of CO flips, studied experimentally.…”

Section: Resultsmentioning

confidence: 94%

Ar:N$_2$ - a non-universal glass

Gaita-Ariño,

González-Albuixech,

Schechter

2014

Preprint

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The bias energies of various two-level systems (TLSs) and their strengths of interactions with the strain are calculated for Ar:N2 glass. Unlike the case in KBr:CN, a distinct class of TLSs having weak interaction with the strain and untypically small bias energies is not found. The addition of CO molecules introduces CO flips which form such a class of weakly interacting TLSs, albeit at much lower coupling than are typically observed in solids. We conclude that because of the absence of a distinct class of weakly interacting TLSs, Ar:N2 is a non-universal glass, the first such system in three dimensions and in ambient pressure. Our results further suggest that Ar:N2:CO may show universal properties, but at temperatures lower than ≈ 0.1 K, much smaller than typical temperature ≈ 3 K associated with universality, because of the untypical softness of this system. Our results thus shed light on two long standing questions regarding low temperature properties of glasses: the necessary and sufficient conditions for quantitative universality of phonon attenuation, and what dictates the energy scale of ≈ 3 K below which universality it typically observed.

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“…The fact that the linear term in the specific heat, corresponding to the DOS of the TLSs, had little if any dependence on the CO concentration, was interpreted as a refutation of the molecular flips as being the relevant TLSs dictating universality. Little attention was paid to the fact that Ar:N 2 did not exhibit universal phonon attenuation as observed in its thermal conductivity [20].…”

mentioning

confidence: 99%

Inversion symmetric vs. asymmetric excitations and the low-temperature universal properties of Ar:N ₂ and Ar:N ₂ :CO glasses

Gaita‐Ariño¹,

González-Albuixech²,

Schechter³

2015

EPL

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The bias energies of various two-level systems (TLSs) and their strengths of interactions with the strain are calculated for Ar:N2 glass. Unlike the case in KBr:CN, a distinct class of TLSs having weak interaction with the strain and untypically small bias energies is not found. The addition of CO molecules introduces CO flips which form such a class of weakly interacting TLSs, albeit at much lower coupling than that at which they are typically observed in solids. We conclude that because of the absence of a distinct class of weakly interacting TLSs, Ar:N2 is a non-universal glass, the first such system in three dimensions and in ambient pressure. Our results further suggest that Ar:N2:CO may show universal properties, but at temperatures lower than ≈ 0.1 K, much smaller than the typical temperature ≈ 3 K associated with universality, because of the untypical softness of this system. Our results thus shed light on two long-standing questions regarding the low-temperature properties of glasses: the necessary and sufficient conditions for quantitative universality of phonon attenuation, and what dictates the energy scale of ≈ 3 K below which universality is typically observed.

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Thermal conductivity of solidN2-Ar alloys

Cited by 10 publications

References 9 publications

Identification of Strong and Weak Interacting Two-Level Systems in KBr:CN

Identification of Strong and Weak Interacting Two-Level Systems in KBr:CN

Ar:N$_2$ - a non-universal glass

Inversion symmetric vs. asymmetric excitations and the low-temperature universal properties of Ar:N ₂ and Ar:N ₂ :CO glasses

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Thermal conductivity of solidN2-Ar alloys

Cited by 10 publications

References 9 publications

Identification of Strong and Weak Interacting Two-Level Systems in KBr:CN

Identification of Strong and Weak Interacting Two-Level Systems in KBr:CN

Ar:N$_2$ - a non-universal glass

Inversion symmetric vs. asymmetric excitations and the low-temperature universal properties of Ar:N 2 and Ar:N 2 :CO glasses

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Product

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Inversion symmetric vs. asymmetric excitations and the low-temperature universal properties of Ar:N ₂ and Ar:N ₂ :CO glasses