Designing the stripe-ordered cuprate phase diagram through uniaxial-stress

TL;DR

This study demonstrates that applying low uniaxial stress to cuprate La_2-xBa_xCuO_4 significantly enhances 3D superconductivity and removes the 1/8-anomaly, revealing a close relationship between stripe order, crystal structure, and superconductivity.

Contribution

The paper shows that uniaxial stress can control and improve superconductivity and stripe order in cuprates, providing new insights into their intertwined physical mechanisms.

Findings

Uniaxial stress increases T_c by sixfold and restores 3D phase coherence.

Stress suppresses the low-temperature tetragonal structure.

Stripe order temperature remains modestly affected by stress.

Abstract

The ability to efficiently control charge and spin in the cuprate high-temperature superconductors is crucial for fundamental research and underpins technological development. Here, we explore the tunability of magnetism, superconductivity and crystal structure in the stripe phase of the cuprate La_2-xBa_xCuO_4, with x = 0.115 and 0.135, by employing temperature-dependent (down to 400 mK) muon-spin rotation and AC susceptibility, as well as X-ray scattering experiments under compressive uniaxial stress in the CuO_2 plane. A sixfold increase of the 3-dimensional (3D) superconducting critical temperature T_c and a full recovery of the 3D phase coherence is observed in both samples with the application of extremely low uniaxial stress of 0.1 GPa. This finding demonstrates the removal of the well-known 1/8-anomaly of cuprates by uniaxial stress. On the other hand, the spin-stripe order temperature as well as the magnetic fraction at 400 mK show only a modest decrease under stress. Moreover, the onset temperatures of 3D superconductivity and spin-stripe order are very similar in the large stress regime. However, a substantial decrease of the magnetic volume fraction and a full suppression of the low-temperature tetragonal structure is found at elevated temperatures, which is a necessary condition for the development of the 3D superconducting phase with optimal T_c. Our results evidence a remarkable cooperation between the long-range static spin-stripe order and the underlying crystalline order with the three-dimensional fully coherent superconductivity. Overall, these results suggest that the stripe- and the SC order may have a common physical mechanism.