Suppression of superconductivity by charge density wave order in YBa$_2$Cu$_3$O$_{6.67}$

Barber, Mark E.; Kim, Hun-ho; Loew, Toshinao; Tacon, Matthieu Le; Minola, Matteo; Konczykowski, Marcin; Keimer, Bernhard; Mackenzie, Andrew P.; Hicks, Clifford W.

doi:10.48550/arxiv.2101.02923

Cited by 4 publications

(4 citation statements)

References 35 publications

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“…We also notice that our results are not at odd with several other situations (e.g. [80][81][82][83]) in which the competition between CDWs and superconductivity has been observed to be detrimental for the critical temperature T c . In fact, as verified by our computations, and already envisaged by the seminal work by Bergmann and Rainer [51], softening does not always lead to an increase of T c .…”

Section: Discussionsupporting

confidence: 55%

Possible enhancement of the superconducting Tc due to sharp Kohn-like soft phonon anomalies

Cunyuan

Enrico

Baggioli

et al. 2023

J. Phys.: Condens. Matter

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Phonon softening is a ubiquitous phenomenon in condensed matter systems which is usually associated with charge density wave (CDW) instabilities and anharmonicity. The interplay between phonon softening, CDW and superconductivity is a topic of intense debate. In this work, the effects of anomalous soft phonon instabilities on superconductivity are studied based on a recently developed theoretical framework that accounts for phonon damping and softening within the Migdal-Eliashberg theory. Model calculations show that the phonon softening in the form of a sharp dip in the phonon dispersion relation, either acoustic or optical (including the case of Kohn-type anomalies typically associated with CDW), can cause a manifold increase of the electron-phonon coupling constant λ. This, under certain conditions, which are consistent with the concept of optimal frequency introduced by Bergmann and Rainer, can produce a large increase of the superconducting transition temperature Tc. In summary, our results suggest the possibility of reaching high-temperature superconductivity by exploiting soft phonon anomalies restricted in momentum space.

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Section: Discussionsupporting

confidence: 55%

Possible enhancement of the superconducting Tc due to sharp Kohn-like soft phonon anomalies

Cunyuan

Enrico

Baggioli

et al. 2023

J. Phys.: Condens. Matter

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“…Recent papers have shown that the CDW order can be tuned by strain externally applied to single crystals [4,[16][17][18][19]. It has been found that hydrostatic pressure increases T c and strongly modifies the CDW order [4,18], while the response to uniaxial strain is more complex [16,20]. In thin films, the strain can be tuned by the choice of substrate and by varying the film thickness [21,22], in contrast to the case of single crystals, where complicated apparatus is required to apply the strain, which might not be compatible with high magnetic field facilities and/or other measurement setups.…”

Section: Introductionmentioning

confidence: 99%

Doping dependence of the upper critical field in untwinned YBa₂Cu₃O 7−δ thin films

Wahlberg

Arpaia

Kalaboukhov

et al. 2022

Supercond. Sci. Technol.

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We report on measurements of the doping dependence of the upper critical field Hc,2 in 50 nm thick YBa2Cu3O7−δ films. The films are untwinned and are characterized by a small in-plane compressive strain. We find that the Hc,2 shows a strong decrease in the underdoped region of the phase diagram, in agreement with what has been measured in relaxed single crystals. The origin of the decrease of Hc,2 in the underdoped regime is discussed within a scenario where charge density wave order competes with superconductivity. This demonstrates the potential of using thin films for studying the phase diagram of high-Tc materials under strain, and opens up the possibility to investigate the interplay between charge density wave order and superconductivity tuned by strain.

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“…Recent developments of piezoelectric-based devices capable of applying uniaxial stress to materials in a nearly continuous fashion, have highlighted the unique roles that anisotropic strain can play ( 2 – 4 ). Its application in strongly correlated electron systems where competing phases are expected to be sensitively tuned by external control parameters ( 5 ) opens up particularly exciting possibilities; in this context, the potential of anisotropic strain as an effective tuning parameter has begun to be demonstrated for a number of superconducting ( 3 , 4 , 6 , 7 ), nematic ( 7 , 8 ), and charge density wave states ( 9 – 11 ). Uniaxial stress, like hydrostatic pressure, couples to these phases by modifying the atomic spacing in the lattice hosts; however, an important difference between the two as material tuning parameters is that hydrostatic pressure should, in principle, preserve the space group symmetry, whereas strain induced by uniaxial stress can modify the space group with relatively small lattice distortions.…”

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confidence: 99%

Elastocaloric signatures of symmetric and antisymmetric strain-tuning of quadrupolar and magnetic phases in DyB ₂ C ₂

Ye,

Sun,

Sunko

et al. 2023

Proc. Natl. Acad. Sci. U.S.A.

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The adiabatic elastocaloric effect measures the temperature change of a given system with strain and provides a thermodynamic probe of the entropic landscape in the temperature-strain space. Here, we demonstrate that the DC bias strain-dependence of AC elastocaloric effect allows decomposition of the latter into symmetric (rotation-symmetry-preserving) and antisymmetric (rotation-symmetry-breaking) strain channels, using a tetragonal f -electron intermetallic DyB 2 C 2 —whose antiferroquadrupolar order breaks local fourfold rotational symmetries while globally remaining tetragonal—as a showcase example. We capture the strain evolution of its quadrupolar and magnetic phase transitions using both singularities in the elastocaloric coefficient and its jumps at the transitions, and the latter we show follows a modified Ehrenfest relation. We find that antisymmetric strain couples to the underlying order parameter in a biquadratic (linear-quadratic) manner in the antiferroquadrupolar (canted antiferromagnetic) phase, which are attributed to a preserved (broken) global tetragonal symmetry, respectively. The broken tetragonal symmetry in the magnetic phase is further evidenced by elastocaloric strain-hysteresis and optical birefringence. Additionally, within the staggered quadrupolar order, the observed elastocaloric response reflects a quadratic increase of entropy with antisymmetric strain, analogous to the role magnetic field plays for Ising antiferromagnetic orders by promoting pseudospin flips. Our results demonstrate AC elastocaloric effect as a compact and incisive thermodynamic probe into the coupling between electronic degrees of freedom and strain in free energy, which holds the potential for investigating and understanding the symmetry of a wide variety of ordered phases in broader classes of quantum materials.

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Suppression of superconductivity by charge density wave order in YBa$_2$Cu$_3$O$_{6.67}$

Cited by 4 publications

References 35 publications

Possible enhancement of the superconducting Tc due to sharp Kohn-like soft phonon anomalies

Possible enhancement of the superconducting Tc due to sharp Kohn-like soft phonon anomalies

Doping dependence of the upper critical field in untwinned YBa₂Cu₃O 7−δ thin films

Elastocaloric signatures of symmetric and antisymmetric strain-tuning of quadrupolar and magnetic phases in DyB ₂ C ₂

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Suppression of superconductivity by charge density wave order in YBa$_2$Cu$_3$O$_{6.67}$

Cited by 4 publications

References 35 publications

Possible enhancement of the superconducting Tc due to sharp Kohn-like soft phonon anomalies

Possible enhancement of the superconducting Tc due to sharp Kohn-like soft phonon anomalies

Doping dependence of the upper critical field in untwinned YBa2Cu3O 7−δ thin films

Elastocaloric signatures of symmetric and antisymmetric strain-tuning of quadrupolar and magnetic phases in DyB 2 C 2

Contact Info

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Doping dependence of the upper critical field in untwinned YBa₂Cu₃O 7−δ thin films

Elastocaloric signatures of symmetric and antisymmetric strain-tuning of quadrupolar and magnetic phases in DyB ₂ C ₂