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

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_xCuO₄, with x = 0.115, 0.125 and 0.135, by employing temperature-dependent (down to 400 mK) muon-spin rotation, AC susceptibility, electrical transport as well as X-ray scattering experiments under compressive uniaxial stress in the CuO₂ plane and along the c-axis [1,2]. 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 all three samples with the application of extremely low in-plane uniaxial stress of 0.1 GPa. This finding demonstrates the removal of the well-known 1/8-anomaly of cuprates by in-plane 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, strain produces an inhomogeneous suppression of the spin stripe order at elevated temperatures. Namely, a substantial decrease of the magnetic volume fraction and a full suppression of the low-temperature tetragonal structure is found under stress, which is a necessary condition for the development of the 3D superconducting phase with optimal T_c. Regarding the c-axis strain, it has a negligible effect on both the superconducting transition temperature and the spin-stripe order. 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.

[1] Z. Guguchia et. al., Proc. Natl. Acd. Sci. U.S.A 121(1), e2303423120 (2024).

[2] V. Sazgari, S.S. Islam, J.N. Graham et. al., and Z. Guguchia, in preparation.