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

J Chang,N B Christensen,E M Forgan,E Blackburn,U Rütt,O Ivashko,Ruixing Liang,D A Bonn,M Hücker,A T Holmes,S M Hayden,M V Zimmermann,W N Hardy

doi:10.1038/ncomms11494

Abstract

The application of magnetic fields to layered cuprates suppresses their high-temperature superconducting behaviour and reveals competing ground states. In widely studied underdoped YBa2Cu3O6+x (YBCO), the microscopic nature of field-induced electronic and structural changes at low temperatures remains unclear. Here we report an X-ray study of the high-field charge density wave (CDW) in YBCO. For hole dopings ∼0.123, we find that a field (B∼10 T) induces additional CDW correlations along the CuO chain (b-direction) only, leading to a three-dimensional (3D) ordered state along this direction at B∼15 T. The CDW signal along the a-direction is also enhanced by field, but does not develop an additional pattern of correlations. Magnetic field modifies the coupling between the CuO2 bilayers in the YBCO structure, and causes the sudden appearance of the 3D CDW order. The mirror symmetry of individual bilayers is broken by the CDW at low and high fields, allowing Fermi surface reconstruction, as recently suggested.

Highlights

The application of magnetic fields to layered cuprates suppresses their high-temperature superconducting behaviour and reveals competing ground states
It is important to determine the nature of the charge density wave (CDW) correlations induced by the magnetic field in YBa2Cu3O6 þ x (YBCO) and their relationship to the electronic properties
The CDW correlations in the cuprates have propagation vectors with the in-plane components parallel to the Cu–O bonds and periodicities of 3 À 4a depending on the system[2,3,5,8]

Summary

Introduction

The application of magnetic fields to layered cuprates suppresses their high-temperature superconducting behaviour and reveals competing ground states. In widely studied underdoped YBa2Cu3O6 þ x (YBCO), the microscopic nature of field-induced electronic and structural changes at low temperatures remains unclear. Magnetic field modifies the coupling between the CuO2 bilayers in the YBCO structure, and causes the sudden appearance of the 3D CDW order. A recent X-ray free-electron laser experiment[24] has shown that a magnetic field of B\15 T induces a new CDW Bragg peak, with a propagation vector along the b axis, corresponding to an extended range of ordering along the c axis and an in-phase correlation of the CDW modulation between the neighbouring bilayers. It is important to determine the nature of the CDW correlations induced by the magnetic field in YBCO and their relationship to the electronic properties. Our data provides insight into the likely high-field structure of the CDW (in the normal state) that is relevant to describe the Fermi surface reconstruction leading to QO

Methods

Results

Conclusion