Charge Order and Fluctuations in Bi2Sr2-xLaxCuO6+δ Revealed by 63,65Cu-Nuclear Magnetic Resonance

The discovery of a magnetic -field-induced charge-density-wave (CDW) order in the pseudogap state via nuclear magnetic resonance (NMR) studies has highlighted the importance of charge in the physics of high transition temperature (T-c) superconductivity in copper oxides (cuprates). Herein, after briefly reviewing the progress achieved in the last few years, we report new results of Cu-63,Cu-65-NMR measurements on the CDW order and its fluctuation in the single-layered cuprate Bi2Sr2-xLaxCuO6+delta. The NMR spectrum under both in-and out-of-plane magnetic fields above H = 10 T indicates that the CDW replaces the antiferromagnetic order before superconductivity appears, but disappears before superconductivity is optimized. We found that the CDW onset temperature TCDW scales with the pseudogap temperature T*. Comparison between Cu-63 and Cu-65 NMR indicates that the spin-lattice relaxation process is dominated by charge fluctuations in the doping regions where the CDW appears as well as at the pseudogap end point (T* = 0). These results suggest that charge orders and fluctuations exist in multiple doping regions and over a quite wide temperature range.

Automated summary

This study discovered a magnetic-field-induced charge-density-wave order in copper oxide superconductors using nuclear magnetic resonance, highlighting the importance of charge in high-temperature superconductivity. The results show that the CDW order replaces the antiferromagnetic order before superconductivity appears and disappears before superconductivity is optimized. The onset temperature of CDW scales with the pseudogap temperature, and charge fluctuations dominate the spin-lattice relaxation process.