The effect of magnetic field on the charge density wave in La_2−xSr_xCuO₄ near the critical end point

The interplay between superconductivity and other competing tendencies has been intensely investigated in high temperature cuprate superconductors. In underdoped La- based cuprates, the charge and spin orders appear to be intertwined to form stripes with the incommensurability δ_charge = 2δ_spin [1]. In contrast, in YBa₂Cu₃O_6+x (YBCO), charge density waves (CDW) and spin density waves (SDW) emerge at different doping indicating that they might compete with each other. These competing tendencies can be tuned by a magnetic field. In YBCO, a magnetic field can give rise to a ferro-type long-range CDW in-phase along the c direction, distinct from the short-range anti-phase CDW at zero field [2,3]. Here, we study the effects of a magnetic field on the CDW of La_2−xSr_xCuO₄ (x = 0.132), a composition close to the end point of the SDW where no SDW is observed at zero field. We find that the magnetic field induces a CDW such that its intensity grows linearly with field. A similar increase in the SDW intensity is observed for the SDW suggesting that the SDW and CDW modulations are strongly coupled as required for example in stripe theories.
[1] J. M. Tranquada et al, Nature 375, 561 (1995).
[2] J. Chang et al, Nat. Comm. 7, 11494 (2016).
[3] J. Choi et al, arXiv 1909.09359 (2019).