Dynamic Competition between Cooper-Pair and Spin-Density-Wave Condensation
B. Decrausaz, M. Pikulski, O. Ivashko, N. B. Christensen, J. Choi, L. Udby, Ch. Niedermayer, K. Lefmann, H. M. Rønnow, J. Mesot, J. Ollivier, T. Kurosawa, N. Momono, M. Oda, J. Chang, D. G. Mazzone
公開日: 2025/1/29
Abstract
Quantum matter phases may co-exist microscopically even when they display competing tendencies. A fundamental question is whether such a competition can be avoided through the elimination of one phase while the other one condenses into the ground state. Here, we present a high-resolution neutron spectroscopy study of the low-energy spin excitations in the high-temperature superconductor La1.855Sr0.145CuO4. In the normal state, we find low-energy magnetic fluctuations at incommensurate reciprocal lattice positions where spin-density-wave order emerges at lower Sr concentration or at high magnetic fields. While these spin excitations are largely suppressed by the emergence of the superconducting spin gap, some low-energy magnetic fluctuations persist deep inside the superconducting state. We interpret this result in terms of a dynamic competition between superconductivity and magnetism, where superconductivity impedes the condensation of low-energy magnetic fluctuations through the formation of magnetically-mediated Cooper pairs.