Talks

coffee, tea, cookies at 16:00 in the main hall
Monday 16:30-17:30
Seminar room 1+2
- monthly seminars -
Seminar room 4
- weekly seminars -
Monday 11:00-12:00
Room 1D1
Wednesday 16:30 - 17:30
Seminar room 1D1
Thursday 14:00-15:00
Seminar room 4

 

 

Talks in chronological order

02 Dec 2021
04:00 PM

From disorder to order and back again

José Hoyos (Instituto de Física de São Carlos)

One of the most surprising phenomena in frustrated magnets is the order-by-disorder mechanism: thermal and/or quantum fluctuations lift a macroscopic accidental degeneracy of the classical ground state of frustrated magnets. The resulting magnetically ordered-by-(thermal/quantum)disorder state often breaks a real-space symmetry of the crystal lattice. In this talk, we use symmetry arguments and Monte Carlo simulations to investigate the effects of impurities (vacancies, chemical doping, etc.). Because inhomogeneities generically break a real-space symmetry, it couples to the order-parameter as a conjugate field. As a consequence, inhomogeneities non-perturbatively destabilize an ordered-by-disorder state at sufficiently low dimensions. As an example, we apply our theory to the J1-J2 Heisenberg model on a square lattice [1] and to the easy-plane pyrochlores [2]. [1] M. Miranda, I. C. Almeida, E. C. Andrade, J. A. Hoyos, Phase diagram of a frustrated Heisenberg model: From disorder to order and back again, Phys. Rev. B 104, 054201 (2021). [2] E. C. Andrade, J. A. Hoyos, S. Rachel, and M. Vojta, Cluster-Glass Phase in Pyrochlore XY Antiferromagnets with Quenched Disorder, Phys. Rev. Lett. 120, 097204 (2018).

VIRTUAL iCal Event
09 Dec 2021
04:00 PM

tba

Andrea Young (UCSB)

VIRTUAL iCal Event
16 Dec 2021
04:00 PM

tba

Lode Pollet (LMU Munich)

VIRTUAL iCal Event