Observation of two Andreev-like energy scales in $L{a}_{2-x}S{r}_{x}Cu{O}_4$ superconductor/normal-metal/superconductor junctions

Abstract

Conductance spectra measurements of highly transparent ramp-type junctions made of superconducting $L{a}_{2-x}S{r}_{x}Cu{O}_4$ electrodes and non superconducting $L{a}_{1.65}S{r}_{0.35}Cu{O}_4$ barrier are reported. At low temperatures below $T_c$, these junctions have two prominent Andreev-like conductance peaks with clear steps at energies ${\Delta }_1$ and ${\Delta }_2$ with ${\Delta }_2>2{\Delta }_1$. No such peaks appear above $T_c$. The doping dependence at 2 K shows that both ${\Delta }_1$ and ${\Delta }_2$ scale roughly as $T_c$. ${\Delta }_1$ is identified as the superconducting energy gap, while a few scenarios are proposed as for the origin of ${\Delta }_2$.

19 pages, 11 figures

References in corpus (4)

• The coherent {\it d}-wave superconducting gap in underdoped La${}_{2-x}$Sr${}_x$CuO${}_4$ as studied by angle-resolved photoemission
• Observation of a d-wave nodal liquid in highly underdoped Bi_2Sr_2CaCu_2O_{8+δ}
• Preeminent role of the Van Hove singularity in the strong-coupling analysis of scanning tunneling spectroscopy for two-dimensional cuprates
• Scanning tunneling spectroscopy characterization of the pseudogap and the x = 1/8 anomaly in La2-xSrxCuO4 thin films

Cited by in corpus (2)

• Pairing and the phase diagram of the normal coherence length ${\xi }_N(T,x)$ above $T_c$ of $L{a}_{2-x}S{r}_{x}Cu{O}_4$ thin films probed by the Josephson effect
• Transport and spectroscopic properties of superconductor - ferromagnet - superconductor junctions of $L{a}_{1.9}S{r}_{0.1}Cu{O}_4$ - $L{a}_{0.67}C{a}_{0.33}Mn{O}_3$ - $L{a}_{1.9}S{r}_{0.1}Cu{O}_4$