2013/03/31 by M. P. M. Dean, G. Dellea, R. S. Springell +11 · 1 citation
Physics and Astronomy · #cond-mat.supr-con #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1038/nmat3723
published as Nature Materials 12, 1019-2023 (2013) · See Nature Materials http://dx.doi.org/10.1038/nmat3723 for Advanced Online Publication
arxiv created 2013/09/04 · arxiv updated 2013/10/24
One of the most intensely studied scenarios of high-temperature superconductivity (HTS) postulates pairing by exchange of magnetic excitations [1]. Indeed, such excitations have been observed up to around optimal doping in the cuprates [2-7]. In the heavily overdoped regime neutron scattering measurements indicate that magnetic excitations have effectively disappeared [8-10], and this was argued to cause the demise of HTS with overdoping [1, 8, 10]. Here we use resonant inelastic x-ray scattering (RIXS), which is sensitive to complementary parts of reciprocal space, to measure the evolution of the magnetic excitations in La2-xSrxCuO4 across the entire phase diagram, from a strongly correlated insulator (x = 0) to a non-superconducting metal (x = 0.40). For x = 0, well-defined magnon excitations are observed [11]. These magnons broaden with doping, but they persist with a similar dispersion and comparable intensity all the way to the non-superconducting, heavily overdoped metallic phase. The destruction of HTS with overdoping is therefore caused neither by the general disappearance nor by the overall softening of magnetic excitations; other factor(s), such as the redistribution of spectral weight, must be considered.