Lorenz number in the optimally doped and underdoped superconductor<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>Eu</mml:mi><mml:msub><mml:mi>Ba</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Cu</mml:mi><mml:mn>3</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mi>y</mml:mi></mml:msub></mml:mrow></mml:math>

Matusiak, Marcin; Wolf, Th.

doi:10.1103/physrevb.72.054508

Cited by 18 publications

(60 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[77] and in Ref. [79], and at the same time a substantial difference of their electrical Hall conductivities, σ xy , as bipolarons virtually do not contribute to σ xy in the twinned samples.…”

Section: B Hall-lorenz Numbermentioning

confidence: 75%

See 1 more Smart Citation

Bose–Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors

Alexandrov

2007

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

Section: B Hall-lorenz Numbermentioning

confidence: 75%

“…Hence one can expect that α becomes small in twinned crystals of Ref. [79]. If the condition α 2 ≪ β is met, then only polarons contribute to the transverse electric and thermal magnetotransport.…”

Section: B Hall-lorenz Numbermentioning

confidence: 94%

Bose–Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors

Alexandrov

2007

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

show abstract

“…Although an additional experimental effort is clearly called for in order to discriminate more definitively between the above predictions, it should be mentioned that more recently a slower-than-linear temperature behaviour of the (electronic) Lorenz ratio has been reported [145][146][147].…”

Section: Holographic Phenomenology: the Cupratesmentioning

confidence: 99%

Demystifying the holographic mystique: A critical review

Khveshchenko¹

2016

Lith. J. Phys.

View full text Add to dashboard Cite

Thus far, in spite of many interesting developments, the overall progress towards a systematic study and classification of various 'strange' metallic states of matter has been rather limited. To that end, it was argued that a recent proliferation of the ideas of holographic correspondence originating from string theory might offer a possible way out of the stalemate. However, after almost a decade of intensive studies into the proposed extensions of the holographic conjecture to a variety of condensed matter problems, the validity of this intriguing approach remains largely unknown. This discussion aims at ascertaining its true status and elucidating the conditions under which some of its predictions may indeed be right (albeit, possibly, for a wrong reason).Keywords: strongly correlated systems, holographic correspondence, transport theory, strange metals, analogue gravity PACS: 71.27.+a Condensed matter holography: the promiseAmong the outstanding grand problems in condensed matter physics is that of a deeper understanding and classification of the so-called 'strange metals' or compressible non-Fermi liquid (NFL) states of the strongly interacting systems. However, despite all the effort and a plethora of the important and nontrivial results obtained with the use of the traditional techniques, this program still remains far from completion.As an alternate approach, over the past decade there have been numerous attempts inspired by the hypothetical idea of holographic correspondence which originated from string/gravity/high energy theory (where it is known under the acronym AdS/ CFT) to adapt its main concepts to various condensed matter (or, even more generally, quantum manybody) systems at finite densities and temperatures [1][2][3][4][5][6][7].In its original context, the bona fide holographic principle postulates that certain d + 1-dimensional ('boundary') quantum field theories (e. g. the maximally supersymmetric SU(N) gauge theory) may allow for a dual description in terms of a string theory which, upon a proper compactification, amounts to a certain d + 2-dimensional ('bulk') supergravity. Moreover, in the strong coupling limit (characterized in terms of the t'Hooft coupling constant λ = g 2 N >> 1) and for a large rank N > > 1 of the gauge symmetry group, the bulk description can be further reduced down to a weakly fluctuating gravity model which can even be treated semiclassically at the lowest (0th) order of the underlying 1/N-expansion.In the practical applications of the holographic conjecture, the partition function of a strongly interacting boundary theory with the Lagrangian L(ϕ a ) would then be approximated by a saddle-point (classical) value of the bulk action described by the Lagrangian L(g μν ,…) which includes gravity and other fields dual to their boundary counterparts [1][2][3][4][5][6][7][8] (1) evaluated with the use of a fixed background metric ,while any quantum corrections would usually be neglected by invoking the small parameter 1/N.

show abstract

“…Remarkably, the measured value of L H just above T c turned out precisely the same as predicted by the bipolaron theory[6], L = 0.15L 0 , where L 0 = π 2 /3 is the conventional Sommerfeld value. The breakdown of the WF law revealed in the Righi-Leduc effect [5] has been explained by a temperature-dependent contribution of thermally excited single polarons to the transverse magneto-transport [7].Surprisingly more recent measurements of the HallLorenz number in single crystals of optimally doped Y Ba 2 Cu 3 O 6.95 and optimally doped and underdoped EuBa 2 Cu 3 O y led to an opposite conclusion [8]. The experimental L H for these samples has turned out only weakly temperature dependent and exceeding the Sommerfeld value by more than 2 times in the whole temperature range from T c up to the room temperature.…”

mentioning

confidence: 99%

“…The theory explains the huge difference in the Hall-Lorenz numbers by taking into account the difference between the in-plane resistivity of detwinned [5] and twinned [8] single crystals. The theory fits well the observed L H (T )s and explains a sharp Hall-number maximum [8] observed in the normal state of underdoped cuprates.In the presence of the electric field E, the temperature gradient ∇T and a weak magnetic field B z ⊥ E and ∇T , the electrical currents in x, y directions are given by j x =a xx ∇ x (µ − 2eφ) + a xy ∇ y (µ − 2eφ) +b xx ∇ x T + b xy ∇ y T, j y =a yy ∇ y (µ − 2eφ) + a yx ∇ x (µ − 2eφ) +b yy ∇ y T + b yx ∇ x T,and the thermal currents are: w x =c xx ∇ x (µ − 2eφ) + c xy ∇ y (µ − 2eφ) +d xx ∇ x T + d xy ∇ y T w y =c yy ∇ y (µ − 2eφ) + c yx ∇ x (µ − 2eφ) +d yy ∇ y T + d yx ∇ x T. …”

mentioning

confidence: 99%

Hall-Lorenz number paradox in cuprate superconductors

Alexandrov

2006

Phys. Rev. B

View full text Add to dashboard Cite

Significantly different normal state Lorenz numbers have been found in two independent direct measurements based on the Righi-Leduc effect, one about 6 times smaller and the other one about 2 times larger than the Sommerfeld value in single cuprate crystals of the same chemical composition. The controversy is resolved in the model where charge carriers are mobile lattice bipolarons and thermally activated nondegenerate polarons. The model numerically fits several longitudinal and transverse kinetic coefficients providing a unique explanation of a sharp maximum in the temperature dependence of the normal state Hall number in underdoped cuprates. PACS numbers: 74.25.Fy,72.15.Eb, Particular interest in studies of high-temperature superconductors lies in a possible violation of the Wiedemann-Franz (WF) law in doped cuprates. A departure from the Fermi/BCS liquid picture is seen in both the superconducting and normal state thermal conductivities and might be related by a common mechanism [1,2]. Takenaka et al. [1] systematically studied the oxygencontent dependence of the insulating state thermal conductivity enabling them to estimate the phononic contribution, κ ph (T ) for the metallic state to some extent. Their analysis led to the conclusion that the electronic term, κ is only weakly T -dependent. This approximately T -independent κ in the underdoped region therefore implies the violation of the WF law since the resistivity is found to be a non-linear function of temperature in this regime. A breakdown of the WF law has been seen in other cuprates such as P r 2−x Ce x CuO 4 at very low temperatures [2]. On the other hand measurements by Proust et al.[3] on T l 2 Ba 2 Cu0 6+δ have suggested that the Wiedemann-Franz law holds perfectly well in the overdoped region. However in any case the extraction of the electronic thermal conductivity has proven difficult and inconclusive as κ and κ ph are comparable at elevated temperatures, or there is a thermal decoupling of phonons and electrons at ultra-low temperatures [4]. This uncertainty has been avoided in measurements of the Righi-Leduc effect. The effect describes transverse heat flow resulting from a perpendicular temperature gradient in an external magnetic field, which is a thermal analog of the Hall effect. Using the effect the "HallLorenz" electronic number, L H = (e/k B ) 2 κ xy /(T σ xy ) has been directly measured [5] in Y Ba 2 Cu 3 O 6.95 and Y Ba 2 Cu 3 O 6.6 since transverse thermal κ xy and electrical σ xy conductivities involve presumably only electrons. The experimental L H (T ) showed a quasi-linear temperature dependence above the resistive T c , which strongly violates the WF law. Remarkably, the measured value of L H just above T c turned out precisely the same as predicted by the bipolaron theory[6], L = 0.15L 0 , where L 0 = π 2 /3 is the conventional Sommerfeld value. The breakdown of the WF law revealed in the Righi-Leduc effect [5] has been explained by a temperature-dependent contribution of thermally excited single polarons to the transverse ...

show abstract

Lorenz number in the optimally doped and underdoped superconductorEuBa2Cu3Oy

Cited by 18 publications

References 28 publications

Bose–Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors

Bose–Einstein condensation of strongly correlated electrons and phonons in cuprate superconductors

Demystifying the holographic mystique: A critical review

Hall-Lorenz number paradox in cuprate superconductors

Contact Info

Product

Resources

About