Defects in correlated metals and superconductors

Alloul, H.; Bobroff, J.; Gabay, M.; Hirschfeld, P. J.

doi:10.1103/revmodphys.81.45

Cited by 477 publications

(539 citation statements)

References 469 publications

Supporting

Mentioning

519

Contrasting

Unclassified

Order By: Relevance

“…Since disorder is known to induce in-gap states and low-energy spin excitations 47 , one might speculate that the diorder in our YBa 2 Cu 3 O 6.45 is considerably larger than those in the YBa 2 Cu 3 O 6.5 10 . In this picture, the large reduction in the spin-gap energy and the broadening of the resonance below the MIC is induced by the sudden increase in the lattice disorder in YBa 2 Cu 3 O 6.45 .…”

Section: Discussionmentioning

confidence: 98%

Quantum spin excitations through the metal-to-insulator crossover inYBa2Cu3O6+y

Yamani

Kang

et al. 2008

Phys. Rev. B

View full text Add to dashboard Cite

We use inelastic neutron scattering to study the temperature dependence of the spin excitations of a detwinned superconducting YBa2Cu3O6.45 (Tc = 48 K). In contrast to earlier work on YBa2Cu3O6.5 (Tc = 58 K), where the prominent features in the magnetic spectra consist of a sharp collective magnetic excitation termed "resonance" and a large (hω ≈ 15 meV) superconducting spin gap, we find that the spin excitations in YBa2Cu3O6.45 are gapless and have a much broader resonance. Our detailed mapping of magnetic scattering along the a * /b * -axis directions at different energies reveals that spin excitations are unisotropic and consistent with the "hourglass"-like dispersion along the a * -axis direction near the resonance, but they are isotropic at lower energies. Since a fundamental change in the low-temperature normal state of YBa2Cu3O6+y when superconductivity is suppressed takes place at y ∼ 0.5 with a metal-to-insulator crossover (MIC), where the ground state transforms from a metallic to an insulating-like phase, our results suggest a clear connection between the large change in spin excitations and the MIC. The resonance therefore is a fundamental feature of metallic ground state superconductors and a consequence of high-Tc superconductivity.

show abstract

Section: Discussionmentioning

confidence: 98%

Quantum spin excitations through the metal-to-insulator crossover inYBa2Cu3O6+y

Yamani

Kang

et al. 2008

Phys. Rev. B

View full text Add to dashboard Cite

show abstract

“…Such an approach was proposed in a model calculation for an inhomogeneous d-wave superconductor with Hubbard-type correlations treated in the mean field [12]. In this model, a single impurity creates, at sufficiently large Hubbard interaction U and impurity potential strength V imp , a droplet of staggered magnetization with a size corresponding to the AF correlation length of the hypothetical pure system [13][14][15][16]. When these droplets come close enough to interact, there is a tendency to form incommensurate, phase-coherent Néel domains whose size is sufficient to explain the observations by Lake et al [2] in zero field [12].…”

mentioning

confidence: 99%

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

et al. 2010

View full text Add to dashboard Cite

Abstract. In underdoped high-T c cuprates, d-wave superconductivity competes with antiferromagnetism. It has generally been accepted that suppressing superconductivity leads to the nucleation of spin-density wave (SDW) order with wavevector near (π, π). We show theoretically, for a d-wave superconductor in an applied magnetic field including disorder and electronic correlations, that the creation of SDW order is in fact not simply due to suppression of superconductivity, but rather due to a correlation-induced splitting of an electronic bound state arising from the sign change of the order parameter along quasiparticle trajectories. The induced SDW order is therefore a direct consequence of the d-wave symmetry. The formation of anti-phase domain walls proves to be crucial for explaining the heretofore puzzling temperature dependence of the induced magnetism as measured by neutron diffraction.A superconductor is characterized by a Bardeen-Cooper-Schrieffer (BCS) order parameter k (R), where R is the center-of-mass coordinate of a Cooper pair of electrons with momenta (k, −k). The bulk ground state of such a system is homogeneous, but a spatial perturbation that breaks pairs, e.g. a magnetic impurity, may cause the suppression of k (R) locally. What is revealed when superconductivity is suppressed is the electronic phase in the absence of k , a normal Fermi liquid. Thus the low-energy excitations near magnetic impurities and in the vortex 4 Author to whom any correspondence should be addressed. [9,10] detected magnetic ordering as a wedge-shaped extension of the 'spin glass' phase into the SC dome of the temperature versus doping phase diagram ( figure 1(a)). Lake et al [2] reported that an incommensurate magnetic order similar to the field-induced state was also observed in zero field. Although it also vanished at T c , the ordered magnetic moment in zero field had a T dependence, which was qualitatively different from the field-induced signal. The zero-field signal was attributed to disorder, but the relation between impurities and magnetic ordering remained unclear. Because strong magnetic fluctuations with similar wavevectors are reported at low but nonzero energies in inelastic neutron scattering experiments on these materials, e.g. on optimally doped LSCO samples exhibiting no spin-glass phase in zero field, it is frequently argued that impurities or vortices simply 'freeze' this fluctuating order [11].Describing such a phenomenon theoretically at the microscopic level is difficult due to the inhomogeneity of the interacting system, but it is important if one wishes to explore situations with strong disorder, where the correlations may no longer reflect the intrinsic spin dynamics of the pure system. Such an approach was proposed in a model calculation for an inhomogeneous d-wave superconductor with Hubbard-type correlations treated in the mean field [12]. In this model, a single impurity creates, at sufficiently large Hubbard interaction U and impurity potential strength V imp , a droplet of staggered magn...

show abstract

“…[2][3][4][5] A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.…”

Section: Introductionmentioning

confidence: 99%

“…2-5 A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.Superconductivity and CDW are traditionally viewed as weakcoupling Fermi surface instabilities due to electron-phonon coupling. 7 Arguments have been made both for their cooperation and competition.…”

mentioning

confidence: 99%

Superconducting order from disorder in 2H-TaSe 2− x S x

Deng

Wang

et al. 2017

npj Quant Mater

View full text Add to dashboard Cite

We report on the emergence of robust superconducting order in single crystal alloys of TaSe 2−x S x (0 ≤ × ≤ 2). The critical temperature of the alloy is surprisingly higher than that of the two end compounds TaSe 2 and TaS 2 . The evolution of superconducting critical temperature T c (x) correlates with the full width at half maximum of the Bragg peaks and with the linear term of the high-temperature resistivity. The conductivity of the crystals near the middle of the alloy series is higher or similar than that of either one of the end members 2H-TaSe 2 and/or 2H-TaS 2 . It is known that in these materials superconductivity is in close competition with charge density wave order. We interpret our experimental findings in a picture where disorder tilts this balance in favor of superconductivity by destroying the charge density wave order.npj Quantum Materials (2017) 2:11 ; doi:10.1038/s41535-017-0016-9 INTRODUCTIONThe interplay of disorder and interactions is a fruitful area of investigation. In the absence of electron-electron interactions, disorder can turn a metallic system into an Anderson insulator, 1 but can remain metallic when interactions are important. The additional complexity of competing orders such superconductivity with charge density wave (CDW) or magnetism makes this problem one of the most challenging frontiers in physics. 2-5 A large body of literature is devoted to this interplay in nearly magnetic materials. 6 The interplay of disorder and superconductivity in CDW materials have been less explored than its magnetic analog.Superconductivity and CDW are traditionally viewed as weakcoupling Fermi surface instabilities due to electron-phonon coupling. 7 Arguments have been made both for their cooperation and competition. 8,9 Hexagonal transition metal dichalcogenide 2H-TaSe 2 (P63/mmc space group) undergoes a second-order transition to an incommensurate CDW at 122 K followed by a first-order lock-in transition to a commensurate CDW (CCDW) phase at 90 K, eventually becoming superconducting below 0.14 K upon cooling. 10, 11 2H-TaS 2 has T c = 0.8 K below an in-plane CCDW at 78 K. 10,12 The CDW mechanism in 2H-TaSe 2 involves an electron instability in the bands nested away from the Fermi surface, whereas 2H-TaS 2 features a polar charge and orbital order. 13,14 CDW in 2H-TaSe 2 is dominated by hopping between next-nearest neighbors that creates three weakly coupled triangular sublattices. 15 It is of interest to note that the 2H-TaSe 2 is quasi-twodimensional (2D) metal with pseudogap and with c-axis resistivity 25-50 times higher than the in-plane resistivity, i.e., ρ c (T) >> ρ ab (T). 10,13,[16][17][18] Here, we report that in the 2H-TaSe 2−x S x alloy series the CDW is suppressed and the superconductivity is maximized with

show abstract

Defects in correlated metals and superconductors

Cited by 477 publications

References 469 publications

Quantum spin excitations through the metal-to-insulator crossover inYBa2Cu3O6+y

Quantum spin excitations through the metal-to-insulator crossover inYBa2Cu3O6+y

d-Wave superconductivity as a catalyst for antiferromagnetism in underdoped cuprates

Superconducting order from disorder in 2H-TaSe 2− x S x

Contact Info

Product

Resources

About