Naslov
Hidden magnetic excitation in the pseudogap phase of a high-Tc superconductor

Autori
Li, V. ; Baledent, V. ; Yu, G. ; Barišić, Nikola ; Hradil, K. ; Mole, R. A. ; Sidis, Y. ; Steffens, P. ; Zhao, X . ; Bourges, P. ; Greven, M.

Izvornik
Nature (0028-0836) 468 (2010), 7321; 283-285

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, pismo, znanstveni

Ključne riječi
magnetic excitation; pseudogap; high-Tc superconductor

Sažetak
The elucidation of thepseudogap phenomenonof the high-transitiontemperature (high-Tc) copper oxides—a set of anomalous physical properties below the characteristic temperature T* and above Tc— has been a major challenge in condensed matter physics for the past two decades1. Following initial indications of broken time-reversal symmetry in photoemission experiments2, recent polarized neutron diffraction work demonstrated the universal existence of an unusual magnetic order belowT* (refs 3, 4). These findings have the profound implication that the pseudogap regime constitutes a genuine new phase of matter rather than a mere crossover phenomenon. They are furthermore consistent with a particular type of order involving circulating orbital currents, and with the notion that the phase diagram is controlled by a quantum critical point5. Here we report inelastic neutron scattering results for HgBa2CuO41d that reveal a fundamental collective magnetic mode associated with the unusual order, and which further support this picture. The mode’s intensity rises below the same temperature T* and its dispersion is weak, as expected for an Ising-like order parameter6. Its energy of 52–56meV renders it a new candidate for the hitherto unexplained ubiquitous electron–bosoncouplingfeaturesobservedinspectroscopicstudies7–10.1. Norman, M. R., Pines, D. & Kallin, C. The pseudogap: friend or foe of high Tc? Adv. Phys. 54, 715–733 (2005). 2. Kaminski, A. et al. Spontaneous breaking of time-reversal symmetry in the pseudogap state of a high-Tc superconductor. Nature 416, 610–613 (2002). 3. Fauque´, B. et al. Magnetic order in the pseudogap phase of high-Tc superconductors. Phys. Rev. Lett. 96, 197001 (2006). 4. Li, Y. et al.Unusualmagnetic order in the pseudogap region of the superconductor HgBa2CuO41d. Nature 455, 372–375 (2008). 5. Varma, C. M. Non-Fermi-liquid states and pairing instability of a general model of copper oxide metals. Phys. Rev. B 55, 14554–14580 (1997). 6. Varma, C. M. Theory of the pseudogap state of the cuprates. Phys. Rev. B 73, 155113 (2006). 7. Lanzara, A. et al. Evidence for ubiquitous strong electron-phonon coupling in hightemperature superconductors. Nature 412, 510–514 (2001). 8. Yang, J. et al. Exchange boson dynamics in cuprates: optical conductivity of HgBa2CuO41d. Phys. Rev. Lett. 102, 027003 (2009). 9. van Heumen, E. et al. Optical determination of the relation between the electronboson coupling function and the critical temperature in high-Tc cuprates. Phys. Rev. B 79, 184512 (2009). 10. Lee, J. et al. Interplay of electron-lattice interactions and superconductivity in Bi2Sr2CaCu2O81d. Nature 442, 546–550 (2006).

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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