Unconventional temperature dependence of the cuprate excitation spectrum

Mauger, A.; Noat, Yves

doi:10.1140/epjb/e2016-70268-2

Cited by 9 publications

(22 citation statements)

References 32 publications

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“…Thus, contrary to BCS where only fermionic excitations are responsible for the destruction of the SC order, here the bosonic character of pairons is the key effect. This conclusion was already discussed in the context of tunneling and ARPES spectra [24,25] and now will be borne out in the present study of the entropy and the specific heat.…”

Section: Pairon Modelsupporting

confidence: 70%

“…Both parameters depend on a single energy scale, the antiferromagnetic exchange energy J [20] and one length scale ξ AF [23]. The pairon model hamiltonian allows to calculate the spectral function as well as the density of states in excellent agreement with the experimental tunneling spectra [24] as well as ARPES, as a function of temperature and doping [25].…”

Section: Pairon Modelmentioning

confidence: 74%

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How ‘pairons’ are revealed in the electronic specific heat of cuprates

Noat

Mauger

Nohara

et al. 2021

Solid State Communications

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Understanding the thermodynamic properties of high-Tc cuprate superconductors is a key step to establish a satisfactory theory of these materials. The electronic specific heat is highly unconventional, distinctly non-BCS, with remarkable doping-dependent features extending well beyond Tc. The pairon concept, bound holes in their local antiferromagnetic environment, has successfully described the tunneling and photoemission spectra. In this article, we show that the model explains the distinctive features of the entropy and specific heat throughout the temperature-doping phase diagram. Their interpretation connects unambiguously the pseudogap, existing up to T * , to the superconducting state below Tc. In the underdoped case, the specific heat is dominated by pairon excitations, following Bose statistics, while with increasing doping, both bosonic excitations and fermionic quasiparticles coexist.

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Section: Pairon Modelsupporting

confidence: 70%

Section: Pairon Modelmentioning

confidence: 74%

How ‘pairons’ are revealed in the electronic specific heat of cuprates

Noat

Mauger

Nohara

et al. 2021

Solid State Communications

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“…Since the mean-field parameter β c is proportional to N oc (T ), as a result of the quasi-Bose transition, the second term represents the condensation energy. As the temperature rises, it gradually decreases and finally vanishes at T c , contrary to the spectral gap [26] -a clear departure from conventional SC.…”

Section: Equations Of Motion With H Int Adding the Term [ã Imentioning

confidence: 85%

From Cooper-pair glass to unconventional superconductivity: a unified approach to cuprates and pnictides

Mauger¹,

Noat²

2017

Solid State Communications

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-We report a microscopic model wherein the unconventional superconductivity emerges from an incoherent 'Cooper-pair glass' state. Driven by the pair-pair interaction, a new type of quasi-Bose phase transition is at work. The interaction leads to the unconventional coupling of the quasiparticles to excited pair states, or 'super-quasiparticles', with a non-retarded energydependent gap. The model describes quantitatively the quasiparticle excitation spectra of both cuprates and pnictides, including the universal 'peak-dip-hump' signatures, and for the pseudogap phase above Tc. The results show that instantaneous pair-pair interactions account for the SC condensation without a collective mode.Despite its wide applications, the BCS theory [1] fails to account for the physical properties of a large variety of high-T c superconductors (SC), the cuprate family, but also the more recent iron-based superconductors. A striking feature of these materials is the proximity to an insulating phase, whether anti-ferromagnetic (cuprates), spin density wave (iron based SC, Bechgard salts) or localization (ultra-thin films). Just beyond the insulating phase, the SC dome appears in the phase diagram as a function of carrier concentration between two critical points. Understanding the transition from such an insulating to SC state is still a major challenge.Microscopic measurements reveal an unconventional quasiparticle (QP) dispersion, the 'peak-dip-hump' structure [2], often attributed to the coupling to a collective mode [3][4][5][6][7][8]. Although the peak to dip energy follows both the neutron resonance and T c as a function of doping [6,9,10], the finer shape of the QP spectra and their temperature dependence remain a challenge. Moreover, in the temperature range [T c , T * ] a pseudogap (PG) state persists, having a Fermi-level gap ∆ p much larger than the critical energy scale k B T c in cuprates (see [11] and ref. therein) and also in iron-based SC [12][13][14].In this letter, these questions are addressed within the pair-pair interaction model (PPI). We show that the main unconventional features of high-T c SC can be understood p-1 arXiv:1612.02268v2 [cond-mat.supr-con]

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“…Note that in this temperature range, the antinodal gap ∆ p (T ) (upper curve), reflecting the total number of pairs, is practically constant up to T c , in agreement with experiment. However for higher temperatures, T > T c the gap ∆ p (T ) markedly decreases to finally vanish at T * as a result of pair dissociation [31].…”

Section: Pair Densitiesmentioning

confidence: 99%

“…Similarly as for the DOS [31], the spectral function A( k, E) can be expressed as a sum of three terms, the condensate spectral function A cond ( k, E), the excited pairs contribution A ex ( k, E) and finally the dissociated pairs term A diss ( k, E). The first term is essentially determined by the number of condensed pairs with energy ∆ p , associated with the quasiparticles…”

Section: Spectral Functionmentioning

confidence: 99%

Origin of the Fermi arcs in cuprates: a dual role of quasiparticle and pair excitations

Mauger¹,

Noat²

2018

J. Phys.: Condens. Matter

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ARPES mesurements in cuprates have given key information on the temperature and angle dependence of the gap (d-wave order parameter, Fermi arcs and pseudogap). We show that these features can be understood in terms of a Bose condensation of interacting pairons (preformed hole pairs which form in their local antiferromagnetic environment). Starting from the basic properties of the pairon wavefunction, we derive the corresponding k-space spectral function. The latter explains the variation of the ARPES spectra as a function of temperature and angle up to T * , the onset temperature of pairon formation. While Bose excitations dominate at the antinode, the fermion excitations dominate around the nodal direction, giving rise to the Fermi arcs at finite temperature. This dual role is the key feature distinguishing cuprate from conventional superconductivity.

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Unconventional temperature dependence of the cuprate excitation spectrum

Cited by 9 publications

References 32 publications

How ‘pairons’ are revealed in the electronic specific heat of cuprates

How ‘pairons’ are revealed in the electronic specific heat of cuprates

From Cooper-pair glass to unconventional superconductivity: a unified approach to cuprates and pnictides

Origin of the Fermi arcs in cuprates: a dual role of quasiparticle and pair excitations

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