Physics at Virginia

"Spin dynamics in two distinct types of classical spin liquids "

Preetha Saha , University of Virginia - Physics
[Host: Gia-Wei Chern]

Unconventional magnetic states such as spin liquids and spin glasses continue to attract the interest of researchers in magnetism.These materials retain their magnetic disorder even at zero temperatures. We study two different cases of frustrated systems  1)In the case of Kitaev-type models frustration originates from highly anisotropic exchange interactions. We report a new classical spin liquid in which the collective flux degrees of freedom break the translation symmetry of the honeycomb lattice. This exotic phase exists in frustrated spin-orbit magnets where a dominant off-diagonal exchange, the so-called Γ term, results in a macroscopic ground-state degeneracy at the classical level [1]. We show that this phase transition actually corresponds to plaquette ordering of hexagonal fluxes. We also study the dynamical behavior of fluxes.  2) We study the deterministic spin precession dynamics using energy conserving Landau-Lifshitz equation on a geometrically frustrated magnet. The lattice constitutes of a triangular arrangement of bipyramids with classical antiferromagnetic Heisenberg interaction. Such a lattice structure is realized in frustrated SrCr9Ga12-9pO19 [SCGO(p)] compounds [2]. Monte Carlo simulations are used to thermalize the system, which is then used as the initial state for the dynamical studies. We explore the temperature, wave vector and frequency dependence in the dynamical structure factor and the corresponding time dependent correlation functions of the model. Dynamics simulations is further used to estimate the extent to which transport of spin excitations in the lattice conform with phenomenological concept of spin diffusion [1]I. Rousochatzakis and N. B. Perkins Phys. Rev. Lett. 118, 147204 (2017). [2]T. Arimori and H. Kawamura J. Phys. Soc. Jpn. 70, 3695 (2001)

Condensed Matter Seminar
Thursday, April 18, 2019
11:00 AM
Physics Building, Room 313
Note special time.
Note special room.

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