Parallel spin stripes and their coexistence with superconducting ground states at optimal and high doping in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>La</mml:mi><mml:mrow><mml:mn>1.6</mml:mn><mml:mo>?</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Nd</mml:mi><mml:mrow><mml:mn>0.4</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi>Sr</mml:mi><mml:mi>x</mml:mi></mml:msub><mml:msub><mml:mi>CuO</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:…

Three-dimensional, commensurate long-range magnetic order in La2CuO4 quickly evolves to quasi-two-dimensional, incommensurate correlations upon doping with mobile holes, and superconductivity follows for x as small 0.05 the La2?xSrx/BaxCuO4 family of superconductors. The onset these systems is known be coincident a remarkable rotation spin from “diagonal stripes” below = “parallel above. However, little about at optimal high levels, around beyond proposed quantum critical point pseudogap phase, p*. Here, we present elastic inelastic neutron scattering measurements on single crystals La1.6?xNd0.4SrxCuO4 0.125, 0.19, 0.24, 0.26 show that two-dimensional, quasistatic, parallel stripes have an temperatures such stripe phase extends p* envelops entirety superconducting ground states this system. We also parameter optimum doping, displays inflection Tc, while low-energy dynamic spectral weight fluctuations grows decreasing temperature saturates Tc.3 MoreReceived 2 September 2020Revised 12 March 2021Accepted 29 April 2021DOI:https://doi.org/10.1103/PhysRevResearch.3.023151Published by American Physical Society under terms Creative Commons Attribution 4.0 International license. Further distribution work must maintain attribution author(s) published article's title, journal citation, DOI.Published SocietyPhysics Subject Headings (PhySH)Research AreasSuperconductivityPhysical SystemsCupratesHigh-temperature superconductorsTechniquesNeutron scatteringCondensed Matter, Materials & Applied Physics