Scanning tunneling spectroscopy characterization of the pseudogap and the x = 1/8 anomaly in La2-xSrxCuO4 thin films

Abstract

Using scanning tunneling spectroscopy we examined the local density of states of thin c-axis La2-xSrxCuO4 films, over wide doping and temperature ranges. We found that the pseudogap exists only at doping levels lower than optimal. For x = 0.12, close to the 'anomalous' x = 1/8 doping level, a zero bias conductance peak was the dominant spectral feature, instead of the excepted V- shaped (c-axis tunneling) gap structure. We have established that this surprising effect cannot be explained by tunneling into (110) facets. Possible origins for this unique behavior are discussed.

arXiv comment15 pages, 6 figures

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• A proximity induced pseudogap - evidence for preformed pairs
• Spatial modulations of mid-gap states in (001)La${}_{1.88}$Sr${}_{0.12}$CuO${}_4$ films: Indications for anti-phase ordering of the d-wave order parameter
• Observation of two Andreev-like energy scales in $L{a}_{2-x}S{r}_{x}Cu{O}_4$ superconductor/normal-metal/superconductor junctions
• Transport and spectroscopic properties of superconductor - ferromagnet - superconductor junctions of $L{a}_{1.9}S{r}_{0.1}Cu{O}_4$ - $L{a}_{0.67}C{a}_{0.33}Mn{O}_3$ - $L{a}_{1.9}S{r}_{0.1}Cu{O}_4$
• A study of the ferromagnetic transition of $SrRu{O}_3$ in nanometer thick bilayers with $YB{a}_{2}C{u}_3{O}_y$, $L{a}_{1.88}S{r}_{0.12}Cu{O}_{4-y}$, Au and Cr: Signature of injected carriers in the pseudogap regime
• Pair density wave solution for a self-consistent model
• Observation of Subharmonic Charge-Density-Wave Correlations in La-Based Cuprates