Parity odd magnetism and spin-phonon coupling in the pseudo-gap phase of cuprate superconductors

MPSD Seminar

  • Datum: 11.05.2016
  • Uhrzeit: 11:00 - 12:00
  • Vortragende(r): Michael Fechner
  • Materials Theory, ETH Zurich
  • Ort: CFEL (Bldg. 99)
  • Raum: Seminar Room IV, O1.111
  • Gastgeber: Andrea Cavalleri
Parity odd magnetism and spin-phonon coupling in the pseudo-gap phase of cuprate superconductors
A characteristic of ferroic materials is the emergence of a temporally static finite expectation value of an order parameter. Here, we introduce a new mechanism [1] for ferroic order, in which a non-zero quasi-static magnetoelectric quadrupolar order appears, mediated by a strong coupling of spin and phonon fluctuations. We show that our proposed mechanism is consistent, to our knowledge, with many experimental observations for the onset of the pseudo-gap phase in cuprate superconductors and therefore propose the quasi-static magnetoelectric quadrupole as a possible pseudo-gap order parameter. By using first-principles calculations in combination with our recent developed formalism [2,3], to calculate multipole moments within a Berry phase approach, we calculate the magnitude of the effect for the the prototypical cuprate superconductor, HgBa2CuO4+δ. Using these results we finally show that our mechanism embraces several key findings of experimental reports and in addition also aspects of previous theoretical models.

[1] M. Fechner, M. J. A. Fierz, F. Thöle, U. Staub, and N. A. Spaldin, arXiv:1510.04844 [cond-mat.supr-con] (2015).

[2] F. Thöle, M. Fechner, and N. A. Spaldin, arXiv:1603.03280 [cond-mat.mtrl-sci] (2016).

[3] N. A. Spaldin, M. Fechner, E. Bousquet, A. Balatsky, and L. Nordström, Phys. Rev. B 88, 094429 (2013).

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