Broken time-reversal symmetry and superconducting states in the cuprates

Kaur, Raminder; Agterberg, D. F.

doi:10.1103/physrevb.68.100506

Cited by 14 publications

(28 citation statements)

References 19 publications

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“…These experimental constraints are the best satisfied using the polarized neutron diffraction on the 4F1 triple-axis spectrometer around the reactor Orphée at the Laboratoire Léon Brillouin (LLB), Saclay (France) In these two figures, a typical magnetic form factor has been used to compute the magnetic structure factor. E) The CC − ΘII phase is a Q=0 AF phase (which belongs to the Eu irreductible representation of the D 4h point group [30,31]): it breaks time reversal symmetry, but preserves lattice translation invariance. As a consequence, the nuclear and magnetic intensity are superimposed on Bragg reflections.…”

Section: Polarized Neutron Techniquementioning

confidence: 99%

“…10, based only on the limited neutron diffraction data although these models are clearly breaking different symmetries. One can nevertheless discuss the allowed symmetries as it has been done by Kaur and Agterberg [30] when considering the additional observation of dichroism in ARPES in Bi2212 [29] which, a priori, is related to the same broken symmetry phase. The observation of dichroism at the M=(π,0) implies that both the fourfold rotation about z axis (C4) and the diagonal mirror planes (σ da , σ db ) are no longer symmetry operations in the pseudogap state.…”

Section: Orbital or Spin Moments ?mentioning

confidence: 99%

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Novel magnetic order in the pseudogap state of high-Tccopper oxides superconductors

Bourgès

Sidis

2011

Comptes Rendus. Physique

104

192

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One of the leading issues in high-Tc copper oxide superconductors is the origin of the pseudogap phase in the underdoped regime of their phase diagram. Using polarized neutron diffraction, a novel magnetic order has been identified as an hidden order parameter of the pseudogap as the transition temperature corresponds to what is expected for the pseudogap. The observed magnetic order preserves translational symmetry as predicted for orbital moments in the circulating current theory. Being now reported in three different cuprates familles, it appears as a universal phenomenon whatever the crystal structure (with single CuO2 layer or bilayer per unit cell). To date, it is the first direct evidence of an hidden order parameter characterizing the pseudogap phase of high-Tc cuprates.To cite this article: P. Bourges and Y. Sidis, C. R. Physique xx (2010). RésuméOrdre magnétique de l'état pseudogap des oxydes de cuivre supraconducteursà haute température critique Un des problèmes majeurs des oxydes de cuivre supraconducteursà haute température critique est l'origine de la phase pseudogap dans l'état sous-dopé. En utilisant des mesures de diffraction de neutrons polarisés, nous avons identifié un ordre magnétique caché qui apparaîtà la température attendue de cetétat de pseudogap. Cet ordre magnétique respecte la symétrie de translation du réseau comme cela aété prédit dans la théorie des boucles de courants circulants. Nous avons généralisé cette découverte dans trois familles distinctes de cuprates. Cette mesure est la première preuve expérimentale directe d'un paramètre d'ordre universel de l'état de pseudogap des oxydes de cuivre supraconducteurs. Pour citer cet article : P. Bourges et Y. Sidis, C. R. Physique xx (2010).

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Section: Polarized Neutron Techniquementioning

confidence: 99%

Section: Orbital or Spin Moments ?mentioning

confidence: 99%

Novel magnetic order in the pseudogap state of high-Tccopper oxides superconductors

Bourgès

Sidis

2011

Comptes Rendus. Physique

104

192

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“…These broken symmetries are expected to continue into the superconducting state, as indeed found in the experiments [2,4]. This should then also affect the symmetry of superconductivity [5,6].Some heavy-fermion superconductors such as CePt 3 Si lack center of inversion in their crystal structure and similar superconducting states are expected for them [7,8]. CePt 3 Si is noncentrosymmetric, antiferromagnetic below 2.2 K, and superconducting below 0.75 K. There is an ongoing debate about its order parameter symmetry [7,9], and the possibility of mixed spin-triplet and spin-singlet pairing has been suggested.…”

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confidence: 58%

Josephson Effect for Superconductors Lacking Time-Reversal and Inversion Symmetries

Léridon

Varma

2007

Phys. Rev. Lett.

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Because of the absence of a center of inversion in some superconducting compounds, a p-wave admixture to the dominant d-wave (or s) order parameter must exist. If time reversal is also violated, an allowed invariant is the product of the d wave (or s wave), p wave, and an appropriately directed current. We show that this leads to a new and remarkable property of the Josephson current for tunneling into a s-wave superconductor along the direction parallel to the axis of the p-wave component. These ideas are applied to the heavy-fermion compounds which lack center of inversion due to crystalline symmetry, as well as time-reversal symmetry, such as CePt 3 Si. They also apply to the superconducting state of the cuprates in the pseudogap region of the phase diagram where in the normal phase some experiments have detected a time-reversal and inversion symmetry broken phase. . These broken symmetries are expected to continue into the superconducting state, as indeed found in the experiments [2,4]. This should then also affect the symmetry of superconductivity [5,6].Some heavy-fermion superconductors such as CePt 3 Si lack center of inversion in their crystal structure and similar superconducting states are expected for them [7,8]. CePt 3 Si is noncentrosymmetric, antiferromagnetic below 2.2 K, and superconducting below 0.75 K. There is an ongoing debate about its order parameter symmetry [7,9], and the possibility of mixed spin-triplet and spin-singlet pairing has been suggested. Thermal conductivity measurements have demonstrated the existence of line nodes [10]. The relatively high value of H c2 (5 T) (above the Pauli-Clogston limit) seems to indicate a spin-triplet superconductor.Here we will show that the Josephson effect between a superconductor breaking inversion symmetry and timereversal symmetry and a conventional s-wave superconductor has a distinct signature from conventional Josephson effect. The clear observation of such effects will further substantiate the nature of the pseudogap phase for the cuprates and the nature of superconductivity in the relevant heavy-fermion compounds.Quite generally, if time-reversal and inversion symmetry are broken, a term in the free-energy of the form ( 1) is allowed. d is the dominant ''d-wave'' superconducting order parameter, px is a ''p-wave'' order parameter, and the coefficient is proportional to the order parameter associated to the symmetry breaking in the normal phase (for example, the crystal structure lacking center of inversion [7] or the spontaneous current loops [1] in cuprates). x corresponds to the (110) direction or the 1 10 direction depending on the domain for the cuprates, and to the c axis for CePt 3 Si. (We have introduced i explicitly in the coefficient so that is real.) In this case a superconducting state violating time-reversal and inversion symmetry and consistent with the proposed normal state is of the generic form d xy i 0 p x;y in zero magnetic field. 0 =2 d , where the leading term in the free energy for the d-wave component is d j d j 2 . Suc...

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“…Due to the admixture of the p x -wave in the gap function, the node, which exists when the symmetry is a pure d-wave, disappears for a doping parameter higher than the limiting value δ 0.12. By means of the SPM we have also evaluated the integrals (5) and (6). It turns out that both the kinetic energy in the HM and the hopping energy in the tJM decrease in the SC state.…”

Section: Spectral Weight and The Kinetic Energymentioning

confidence: 99%

“…A locally nodeless order parameter [5] accounts for the enhanced density of states observed in the vortex core in tunneling measurements. A mixed singlet triplet paring d+ip has been invoked [6] to account for the time-reversal breaking in the pseudogap phase and in the SC phase in Bi 2 Sr 2 CaCu 2 O 8+δ . We are going to demonstrate in this paper that such mixing may be generated in a microscopic model, i.e.…”

Section: Introductionmentioning

confidence: 99%

Unconventional Superconductivity, Spontaneous Time-Reversal Symmetry Breaking and Lowering of Kinetic Energy in Doped, Short-Range Antiferromagnets

Wróbel

Macia̧g²,

Eder³

et al. 2004

Acta Phys. Pol. A

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In this paper we focus on the anomalous temperature dependence of the in-plane conductivity and symmetry mixing of the superconducting order parameter observed in various experiments on cuprates. We show that the one-band Hubbard model is not capable of describing the physics of cuprates because the kinetic energy is lowered in this model in the superconducting state, which contradicts experimental observations. The proper model to investigate doped, short--range antiferromagnets is the t−J model, for which our results agree with experiments. We analyze a spin polaron model, that is an effective model for a doped antiferromagnet. In the framework of this model we also study the superconducting order-parameter symmetry-mixing phenomenon. We show that the expected mixing of d-wave symmetry with p-wave symmetry takes place in the superconducting order-parameter at a finite value of the doping parameter. This symmetry mixing brakes the time-reversal symmetry.

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Broken time-reversal symmetry and superconducting states in the cuprates

Cited by 14 publications

References 19 publications

Novel magnetic order in the pseudogap state of high-Tccopper oxides superconductors

Novel magnetic order in the pseudogap state of high-Tccopper oxides superconductors

Josephson Effect for Superconductors Lacking Time-Reversal and Inversion Symmetries

Unconventional Superconductivity, Spontaneous Time-Reversal Symmetry Breaking and Lowering of Kinetic Energy in Doped, Short-Range Antiferromagnets

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