Equilibrium and non-equilibrium dynamics of highly frustrated quantum magnets

09/29/2020 - 3:30pm to 5:00pm
Speaker(s) / Presenter(s): 
Professor Hitesh Changlani

Professor Hitesh Changlani

Department of Physics 

Florida State University

and The National High Magnetic Field Laboratory

Host:  Kaul



Geometrically frustrated magnets harbor novel phases of strongly interacting quantum matter, including those with fractionalized excitations, such as quantum spin liquids.  While there is tremendous progress on understanding their ground state properties, I will primarily focus on their dynamics by highlighting two directions that my group is pursuing. First, I will present our work (done in collaboration with experimentalists) on a newly synthesized pyrochlore, NaCaNi2F7, which we find to be an almost ideal realization of a spin-1 three-dimensional highly frustrated antiferromagnet with no magnetic order and a continuum of excitations, as seen in inelastic neutron scattering [1]. We determine its effective Hamiltonian and show the presence of characteristic "pinch points”, along with good quantitative agreement at intermediate energy scales, from three different theoretical techniques [2]. In the second part of my talk, I switch my focus to the dynamical non-equilibrium effect of ``quantum scarring” which was first reported in a one dimensional Rydberg atom setup [3], with no known real material analog. I demonstrate that this effect is not restricted to 1D, and can be realized in higher dimensional systems [4], which I explain with the help of an exactly solvable point (that we recently discovered) in the XXZ-Heisenberg model on the frustrated kagome lattice [5]. Within the framework of this proposal, I suggest what would be needed to realize scarring in real materials.

[1] K. W. Plumb, H.J. Changlani, A. Scheie, S. Zhang, J. Krizan, J. A. Rodriguez-Rivera, Y.Qiu, B.Winn, R.J. Cava, C.L. Broholm, Nature Physics, 15, 54-59 (2019)

[2] S. Zhang, H.J. Changlani, K. Plumb, O. Tchernyshyov, R. Moessner, Phys. Rev. Lett. 122, 167203 (2019)

[3] H. Bernien et al., Nature 551, 579–584 (2017); C. Turner et al., Nature Physics 14, 745-749 (2018)

[4] K. Lee, R. Melendrez, A. Pal, H.J. Changlani, Phys. Rev. B 101, 241111(R) (2020)

[5] H.J. Changlani, D. Kochkov, K. Kumar, B. Clark, E. Fradkin, Phys. Rev. Lett. 120, 117202 (2018)




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