Related papers: Large Ca Isotope Effect in CaC6
Isotope effect with a large coefficient $\alpha=-\partial \ln T_c/\partial \ln M$ is usually taken as an evidence of phonon mediated superconductors in the Bardeen-Cooper-Schrieffer (BCS) theory. However, in cuprates which are now widely…
We report the pressure and temperature dependence of the phonon density-of-states in superconducting Ca0.6Na0.4Fe2As2 (Tc=21 K) and the parent compound CaFe2As2, using inelastic neutron scattering. We observe no significant change in the…
In this work, we study thermal conductivity (k) of BC5, an ultra-hard diamondlike semiconductor material, using first-principles computations and analyze the effect of both isotopic disorder as well as length scale dependence. k of…
Motivated by predictions of a substantial contribution of the "buckling" vibration of the CuO2 layers to d-wave superconductivity in the cuprates, we have performed an inelastic neutron scattering study of this phonon in an array of…
Using the density-functional perturbation theory with structural optimization, we investigate the electronic structure, phonon spectra, and superconductivity of BiS2-based layered compounds LaO1-xFxBiS2. For LaO0.5F0.5BiS2, the calculated…
Sc$_3$CoC$_4$ is the only superconductor in the group of the isotypic carbides Sc$_3M$C$_4$ ($M$ = Mn, Fe, Ru, Os, Co, Rh, Ir, Ni), rendering it into an ideal benchmark system to systematically study the prerequisites and mechanism of…
Using the large-$N$ limit of the $t$-$J$ model and allowing also for phonons and the electron-phonon interaction we study the isotope effect $\alpha$ for coupling constants appropriate for YBCO. We find that $\alpha$ has a minimum at…
Microwave penetration depth $\lambda$ and surface resistance at 27 GHz are measured in high quality crystals of KOs$_2$O$_6$. Firm evidence for fully-gapped superconductivity is provided from $\lambda(T)$. Below the second transition at…
The properties of the d-wave superconducting state in the two-dimensional system have been studied. It has been assumed, that the pairing mechanism is based on the electron-phonon and the electron-electron-phonon interactions. The obtained…
We examine the isotope effect of superconductivity in systems with coexisting interactions of phonon and nonphonon mechanisms in addition to the direct Coulomb interaction. The interaction mediated by the spin fluctuations is discussed as…
We observe a characteristic energy $\hbar\omega_{c}\approx 2.1$ eV which separates regions of different behavior of the phonon intensities in the Raman spectra of the $R\rm Ba_2Cu_3O_7$ system. A superconductivity-induced drop of phonon…
We calculate the isotope coefficients $\alpha$ and $\alpha^\ast$ for the superconducting critical temperature $T_c$ and the pseudogap temperature $T^\ast$ in a mean-field treatment of the t-J model including phonons. The pseudogap phase is…
We have measured element-specific Fe-phonon densities of states (Fe-PDOS) of LaFeAsO_{1-x}F_{x} (x = 0, 0.11) and La_{1-x}Ca_{x}FePO (x = 0.13) by using nuclear resonant inelastic scattering of synchrotron radiation. The Fe-PDOS of…
Interfacial phonons between iron-based superconductors (FeSCs) and perovskite substrates have received considerable attention due to the possibility of enhancing preexisting superconductivity. Using scanning tunneling spectroscopy, we…
This article improves the BCS theory to include the inverse isotope effect on superconductivity. An affective model can be deduced from the model including electron-phonon interactions, and the phonon-induced attraction is simply and…
Conventional superconductivity, as used in this review, refers to electron-phonon coupled superconducting electron-pairs described by BCS theory. Unconventional superconductivity refers to superconductors where the Cooper pairs are not…
The discovery of superconductivity at 203K in SH$_3$ is an important step toward higher values of $T_c$. Predictions based on state-of-the-art DFT for the electronic structure, including one preceding experimental confirmation, showed the…
We study the newly discovered Pt phosphides $A$Pt$_3$P ($A$=Sr, Ca, La) [ T. Takayama et al. Phys. Rev. Lett. 108, 237001 (2012)] using first-principles calculations and Migdal-Eliashberg theory. Given the remarkable agreement with the…
By means of neutron inelastic scattering, magnetic excitations and phonons were measured for a single crystal of slightly overdoped superconductor Ca10Pt4As8(Fe1-xPtxAs)10 (x ~ 0.2) with the transition temperature Tc of ~33 K. Below Tc,…
Anisotropic pairing interactions mediated by phonons are examined in layer systems. It is shown that the screening effects become weaker when the layer spacing increases. Then the anisotropic components of the pairing interactions increase…