Magnetic field controlled charge density wave coupling in underdoped YBa2Cu3O6+x

Area of Science:

• Condensed Matter Physics
• Materials Science
• Superconductivity

Background:

• Layered cuprates, like YBa2Cu3O6+x (YBCO), exhibit high-temperature superconductivity suppressed by magnetic fields.
• Competing electronic ground states emerge under magnetic fields, but their microscopic nature in YBCO is not fully understood.

Purpose of the Study:

• To investigate the high-field charge density wave (CDW) in underdoped YBa2Cu3O6+x using X-ray diffraction.
• To elucidate the field-induced electronic and structural changes at low temperatures.

Main Methods:

• X-ray diffraction study under high magnetic fields (up to ~15 T).
• Analysis of charge density wave correlations in YBCO at specific hole doping levels (~0.123).

Main Results:

• A magnetic field of ~10 T induces additional CDW correlations exclusively along the CuO chain (b-direction).
• A three-dimensional (3D) ordered CDW state along the b-direction emerges at ~15 T.
• CDW signal along the a-direction is enhanced by the field but does not form additional correlations.
• Magnetic field modifies inter-bilayer coupling and breaks mirror symmetry within CuO2 bilayers.

Conclusions:

• The study reveals the emergence of a field-induced 3D CDW state in YBCO, primarily along the b-direction.
• This field-induced CDW order is linked to modifications in bilayer coupling and symmetry breaking, enabling Fermi surface reconstruction.