Contrasting c-axis and in-plane uniaxial stress effects on superconductivity and stripe order in La1.885Ba0.115CuO4.

The cuprate superconductor La_2-x Ba _x CuO₄ (LBCO) near x = 0.125 is a striking example of intertwined electronic orders, where 3D superconductivity is anomalously suppressed, allowing spin and charge stripe order to develop. Understanding this interplay remains a key challenge in cuprates, highlighting the necessity of external tuning for deeper insight. While in-plane uniaxial stress enhances superconductivity and suppresses stripe order, the effects of c-axis compression remains largely unexplored. Here, we use muon spin rotation (μSR) and AC susceptibility with an in situ piezoelectric stress device to investigate the spin-stripe order and superconductivity in LBCO-0.115 under c-axis compression. The measurements reveal a gradual suppression of the superconducting transition temperature (T _c) with increasing c-axis stress, in stark contrast to the strong enhancement observed under in-plane stress. We further show that while in-plane stress rapidly reduces both the magnetic volume fraction (V _m) and the spin-stripe ordering temperature (T _so), c-axis compression has no effect, with V _m and T _so exhibiting an almost unchanged behavior up to the highest applied stress of 0.21 GPa. These findings demonstrate a strong anisotropy in stress response.