Temperature and field dependence of the intrinsic tunnelling structure in overdoped 
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Benseman, Timothy; Cooper, J. R.

doi:10.1103/physrevb.98.014507

Cited by 8 publications

(13 citation statements)

References 51 publications

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“…The inset to (b) shows that the minimum value increases as T c (estimated from the peak in specific heat) goes to zero. As found previously 66 , near T c the pair-breaking scattering rate diverges, reflecting superconducting fluctuations, and is responsible for the gap-filling behaviour observed in ARPES [31][32][33] , tunneling [34][35][36] and Raman 37,38 spectroscopies.…”

Section: Specific Heatsupporting

confidence: 72%

“…This is evidenced by specific heat [18][19][20][21][22] , NMR 23 , magnetic penetration depth [24][25][26][27][28][29] and THz spectroscopy 30 measurements. ii) The jump in specific heat at T c and the superfluid density at T = 0 decrease towards zero (a consequence of i)) iii) As temperature increases to T c , angle-resolved photoemission spectroscopy (ARPES) [31][32][33] , tunneling [34][35][36] and Raman spectroscopy 37,38 experiments have revealed that the superconducting gap fills-in rather than closes. This is at odds with BCS theory 39 , even though the ratio of the gap magnitude to T c is close to the d-wave weak-coupling BCS value 22,40 .…”

Section: Introductionmentioning

confidence: 99%

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Hall number, specific heat and superfluid density of overdoped high-Tc cuprates

Storey

2020

Preprint

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Despite often being dismissively described as exhibiting conventional Fermi-liquid-like behaviour, heavily overdoped high-Tc cuprates sport several unexpected features. Thermodynamic properties expected to be roughly constant with doping decrease towards zero, signalling that a growing fraction of carriers remain in the normal state below Tc. Near Tc, the superconducting energy gap fills in with temperature, contrary to the expectations of BCS theory. Most recently a transition in the Hall number of some cuprates was found to extend to a very high doping (x ≈ 0.27), far beyond the pseudogap critical point identified by a peak in thermodynamic properties (x = 0.19). This presents a challenge to the view that the pseudogap is a consequence of Fermi surface reconstruction. In this paper we present a consistent explanation for all these observations by combining pair-breaking scattering with a Fermi surface reconstruction model for the pseudogap. Notably, an increase in pair-breaking with doping leads to a separation of the points where reconstruction begins and the thermodynamic properties peak. This result highlights pair-breaking as an essential ingredient in the electronic recipe for heavily overdoped cuprate superconductors.

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Section: Specific Heatsupporting

confidence: 72%

Section: Introductionmentioning

confidence: 99%

Hall number, specific heat and superfluid density of overdoped high-Tc cuprates

Storey

2020

Preprint

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“…Figure 3 shows plotted as a function of for T = 6, 8, 10, 12 and 14 K. Above 1 tesla the behaviour is linear, consistent with the expected phenomenology of the Volovik effect. Such behaviour has been seen in the specific heats of single-crystal Y123 28 and 29 , and in interlayer tunneling in Bi2212 30 . For d -wave symmetry, in the superconducting state the finite ground-state specific heat coefficient is 29 in units of mJ/g.at.…”

Section: Volovik Effectmentioning

confidence: 78%

“…Figure 3 shows γ (T, H) plotted as a function of √ µ 0 H for T = 6, 8, 10, 12 and 14 K. Above 1 tesla the behaviour is linear, consistent with the expected phenomenology of the Volovik effect. Such behaviour has been seen in the specific heats of single-crystal Y123 28 and La 2−x Sr x CuO 4 29 , and in interlayer tunneling in Bi2212 30 . For d-wave symmetry, in the superconducting state the finite ground-state specific heat coefficient is 29 in units of mJ/g.at.K 2 , where V M is the molar volume, d the unit cell length, φ 0 the flux quantum, 0 is the antinodal amplitude of the d-wave gap, and k F the Fermi wave vector at the node along the ( π,π ) direction.…”

Section: Volovik Effectmentioning

confidence: 80%

Field-dependent specific heat of the canonical underdoped cuprate superconductor $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$

Tallon

Loram

2020

Sci Rep

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The cuprate superconductor $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$ YBa 2 Cu 4 O 8 , in comparison with most other cuprates, has a stable stoichiometry, is largely free of defects and may be regarded as the canonical underdoped cuprate, displaying marked pseudogap behaviour and an associated distinct weakening of superconducting properties. This cuprate ‘pseudogap’ manifests as a partial gap in the electronic density of states at the Fermi level and is observed in most spectroscopic properties. After several decades of intensive study it is widely believed that the pseudogap closes, mean-field like, near a characteristic temperature, $$T^*$$ T ∗ , which rises with decreasing hole concentration, p. Here, we report extensive field-dependent electronic specific heat studies on $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$ YBa 2 Cu 4 O 8 up to an unprecedented 400 K and show unequivocally that the pseudogap never closes, remaining open to at least 400 K where $$T^*$$ T ∗ is typically presumed to be about 150 K. We show from the NMR Knight shift and the electronic entropy that the Wilson ratio is numerically consistent with a weakly-interacting Fermion system for the near-nodal states. And, from the field-dependent specific heat, we characterise the impact of fluctuations and impurity scattering on the thermodynamic properties.

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“…Experimentally these are seen most easily from a field-dependent downturn in the inplane electrical resistivity and a diamagnetic contribution to the static susceptibility. It is not widely recognised that in overdoped Bi2212 superconducting fluctuations can also reduce the electronic density of states (DOS) at the Fermi level [50][51][52] and hence decrease the spin susceptibility and affect all other properties which depend on the DOS. Although we are not aware of an explicit theoretical treatment, in our work a decrease in the measured electronic entropy as T c is approached from above must mean that there is a decrease in the electronic DOS.…”

Section: 2mentioning

confidence: 99%

Locating the pseudogap closing point in cuprate superconductors: absence of entrant or reentrant behavior

Tallon,

Storey,

Cooper

et al. 2019

Preprint

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Current descriptions of the pseudogap in underdoped cuprates envision a doping-dependent transition line T * (p) which descends monotonically towards zero just beyond optimal doping. There is much debate as to the location of the terminal point p * where T * (p) vanishes, whether or not there is a phase transition at T * and exactly how T * (p) behaves below Tc within the superconducting dome. One perspective sees T * (p) cutting the dome and continuing to descend monotonically to zero at pcrit ≈ 0.19 holes/Cu − referred to here as 'entrant behavior'. Another perspective derived from photoemission studies is that T * (p) intersects the dome near pcrit ≈ 0.23 holes/Cu then turns back below Tc, falling to zero again around pcrit ≈ 0.19 − referred to here as 'reentrant behavior'. By examining thermodynamic data for Bi2Sr2CaCu2O 8+δ we show that neither entrant nor reentrant behavior is experimentally supported. Rather, pcrit ≈ 0.19 sharply delimits the pseudogap regime and for p < 0.19 the pseudogap is always present, independent of temperature. Similar results are found for Y0.8Ca0.2Ba2Cu3O 7−δ . For both materials T * (p) is not a temperature but a crossover scale, ≈ E * (p)/2kB, reflecting instead the underlying pseudogap energy E * (p) which vanishes as p → 0.19.

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Temperature and field dependence of the intrinsic tunnelling structure in overdoped Bi2Sr2CaCu2O8+δ

Cited by 8 publications

References 51 publications

Hall number, specific heat and superfluid density of overdoped high-Tc cuprates

Hall number, specific heat and superfluid density of overdoped high-Tc cuprates

Field-dependent specific heat of the canonical underdoped cuprate superconductor $$\hbox {YBa}_2\hbox {Cu}_4\hbox {O}_8$$

Locating the pseudogap closing point in cuprate superconductors: absence of entrant or reentrant behavior

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