arXiv subjects

F. La Mattina

Publications and source records attributed to F. La Mattina.

4 recordsLinked to original sources

arXiv2006

Mixed order parameter symmetries in cuprate superconductors

The recent observation of an inflection point in the temperature dependence of the in-plane magnetic field dependence (lambda_ab) is investigated within a two-band model with coupled order parameters of different symmetries. While the dominant order parameter has d-wave symmetry, the smaller one is of s-wave symmetry. Superconductivity is robust in the d-wave channel and induced via interband interactions in the s-wave subsystem.

cond-mat.supr-con↗

arXiv2006

Evidence for complex order parameter in La_{1.83}Sr_{0.17}CuO_4

The in-plane magnetic field penetration depth (λ_{ab}) in single-crystal La_{1.83}Sr_{0.17}CuO_4 was investigated by means of the muon-spin rotation (\muSR) technique. The temperature dependence of λ^{-2}_{ab} has an inflection point around 10-15K, suggesting the presence of two superconducting gaps: a large gap (Δ_1^d) with d-wave and a small gap (Δ_2^s) with s-wave symmetry. The zero-temperature values of the gaps at μ_0H=0.02T were found to be Δ_1^d(0)=8.2(2)meV and Δ_2^s(0)=1.57(8)meV.

cond-mat.supr-con↗

arXiv2006

Muon-spin-rotation measurements of the penetration depth in Li_2Pd_3B

Measurements of the magnetic field penetration depth $λ$ in the ternary boride superconductor Li$_2$Pd$_3$B ($T_c\simeq7.3$ K) have been carried out by means of muon-spin rotation ($μ$SR). The absolute values of $λ$, the Ginzburg-Landau parameter $κ$, and the first $H_{c1}$ and the second $H_{c2}$ critical fields at T=0 obtained from $μ$SR were found to be $λ(0)=252(2)$ nm, $κ(0)=27(1)$, $μ_0H_{c1}(0)=9.5(1)$ mT, and $μ_0H_{c2}(0)=3.66(8)$ T, respectively. The zero-temperature value of the superconducting gap $Δ_0=$1.31(3) meV was found, corresponding to the ratio $2Δ_0/k_BT_c=4.0(1)$. At low temperatures $λ(T)$ saturates and becomes constant below $T\simeq 0.2T_c$, in agreement with what is expected for s-wave BCS superconductors. Our results suggest that Li$_2$Pd$_3$B is a s-wave BCS superconductor with the only one isotropic energy gap.

cond-mat.supr-con↗

arXiv2004

Study of the magnetic penetration depth in RbOs_2O_6

Measurements of the magnetic field penetration depth λin the pyrochlore superconductor RbOs_2O_6 (T_c\simeq6.3 K) were carried out by means of the muon-spin-rotation (\muSR) technique. At low temperatures λ^{-2}(T) saturates and becomes constant below T\simeq 0.2T_c, in agreement with what is expected for weak-coupled s-wave BCS superconductors. The value of λat T=0 was found to be in the range of 250 nm to 300 nm. \muSR and equilibrium magnetization measurements both reveal that at low temperatures $λ$ is almost (at the level of 10%) independent of the applied magnetic field. This result suggests that the superconducting energy gap in RbOs_2O_6 is isotropic.

cond-mat.supr-con↗