Anomalous isotopic effect near the charge-ordering quantum criticality

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Criticality

Background:

• Cuprates exhibit complex electronic phases, including pseudogaps and superconductivity.
• The interplay between charge ordering and pseudogap phenomena is not fully understood.
• Understanding the role of quantum criticality in these phases is crucial.

Purpose of the Study:

• To investigate the pseudogap opening in cuprates within the Hubbard-Holstein model.
• To determine the influence of charge-ordering quantum criticality (stripe formation) on pseudogap thermodynamics.
• To analyze the isotopic dependence of pseudogap and superconducting transition temperatures.

Main Methods:

• Theoretical evaluation within the Hubbard-Holstein model.
• Analysis of crossover lines related to pseudogap formation.
• Investigation of isotopic effects on critical fluctuations and transition temperatures.

Main Results:

• Isotopic dependence due to critical fluctuations leads to a significant positive shift in pseudogap-formation temperature (T(*)).
• The isotopic shift of the superconducting critical temperature (T(c)) is negligible in optimally and overdoped cuprates.
• A negative and increasing isotopic shift of T(c) is observed upon underdoping.

Conclusions:

• Charge-ordering quantum criticality (stripe formation) plays a key role in pseudogap formation.
• The dynamical nature of charge ordering can explain the variability in experimental T(*) values.
• Isotopic effects provide insights into the distinct mechanisms governing pseudogap and superconducting transitions.