Elucidating the relationship between superconductivity and charge order is one of the central issues of high-temperature superconducting cuprates. La_1.6-xNd_0.4Sr_xCuO₄ (LNSCO) shows charge and spin stripe order, which appears covering a superconducting dome in the electronic phase diagram. It turned out that pressure effectively suppresses the charge stripe order, leading to an enhancement of T_c [1,2]. However, it remains unknown how the electronic state evolves with pressure after the suppression of the stripe order.

In this study, we investigated the pressure effect on transport properties of LNSCO over a wide doping range from x = 0.07 to 0.25. For all compositions measured, application of pressure suppresses the stripe order and hence increases a superconducting transition temperature T_c, consistent with the previous studies. We found that low-temperature resistivity decreases with pressure up to 4–6 GPa due to the suppression of the stripe order and turns to increase at higher pressures, giving rise to a resistivity upturn for x ≤ 0.20. The high-pressure resistivity upturn was widely observed from underdoped to overdoped regime. At the verge of the superconducting dome (x = 0.25), however, the resistivity upturn was absent even at 20 GPa. The pressure-induced resistivity upturn can be attributed to a charge order distinct from the stripe order at low pressures and has a close relationship with superconductivity.

[1] S. Arumugam et al., Phys. Rev. Lett. 88, 247001 (2002).

[2] M. K. Crawford et al., Phys. Rev. B 71, 104513 (2005).