Understanding the superconductivity and charge density wave interaction through quasi-static lattice fluctuations

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Unconventional superconductors exhibit intertwined charge and lattice degrees of freedom.
• In cuprates, charge density wave (CDW) order is suspected to intertwine with superconductivity, but the interaction remains unclear.
• Understanding these intertwined states is crucial for advancing superconductor science.

Purpose of the Study:

• To investigate the interplay between superconductivity and charge density waves (CDW) in underdoped YBa2Cu3O6+x.
• To probe subtle lattice fluctuations and their dynamics using advanced X-ray techniques.
• To elucidate the role of atomic relaxations in the electronic physics of cuprates.

Main Methods:

• Utilized X-ray photon correlation spectroscopy (XPCS) to measure quasi-static lattice fluctuations.
• Analyzed relaxational dynamics of the atomic lattice over extended timescales (thousands of seconds).
• Examined the momentum dependence of the intermediate scattering function.

Main Results:

• Observed significantly faster atomic lattice relaxational dynamics approaching the superconducting transition (Tc ≈ 65 K).
• Found that the intermediate scattering function scales with atomic relaxation distance above Tc in the presence of CDW.
• This scaling trend reverses at other temperatures, indicating a unique state above Tc.

Conclusions:

• The findings suggest an incipient charge density wave (CDW) state stabilized by local strain in the cuprate lattice.
• Relaxational atomic fluctuations play a critical role in the electronic properties of disordered cuprate superconductors.
• This research offers new insights into the complex physics governing intertwined orders in unconventional superconductors.