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
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).