ELFT HÍRADÓ

[Szeminárium koordinátor <szfi-seminar AT wigner.hun-ren.hu>]

PhD házivédés
Vörös Dániel
(Wigner FK SZFI)
Kvantum spinfolyadékok SU(N) Heisenberg-modellekben: dinamikus korrelációk 
vizsgálata Variációs Monte Carlo módszerekkel
During my PhD, I examined the dynamic spin structure factor of quantum spin 
liquids using a numerical variational Monte Carlo method. In this method, the 
ground state is approximated by a Gutzwiller-projected Fermi sea obtained 
from mean-field theory, and the excited states are constructed in the 
subspace of Gutzwiller-projected particle-hole excitations.  First, I 
validated the method on the SU(3) symmetric Heisenberg chain by comparing the 
results against exact diagonalization, Bethe ansatz, DMRG, and conformal 
field theory, all of which showed excellent agreement [1].  Next, I applied 
the method to the SU(4) antiferromagnetic Heisenberg model on the honeycomb 
lattice—previously proposed to host a Dirac spin liquid (DSL) ground state. 
The calculations revealed a gapless continuum of fractionalized excitations 
[2].  Finally, I proposed a Dirac spin liquid as the ground state of the 
SU(6) antiferromagnetic Heisenberg model on the kagome lattice. To reach this 
conclusion, I investigated the energetical stability of the DSL against 
perturbations of the mean-field ansatz. The dynamical spin structure factor 
also shows a gapless continuum of fractionalized excitations [3]. These 
findings may help experimental identification of Dirac spin liquids, 
particularly in ultracold atom systems on optical lattices and 
spin-orbit-entangled materials.[1] D. Vörös and K. Penc, Dynamical structure 
factor of the SU(3) Heisenberg chain: Variational Monte Carlo approach 
Physical Review B 104 184426/1-19 (2021)[2] D. Vörös and K. Penc, Dynamical 
structure factor of the SU(4) algebraic spin liquid on the honeycomb lattice 
Physical Review B 108 214407/1-10 (2023)[3] D. Vörös, P. Kránitz and K. Penc, 
The algebraic spin liquid in the SU(6) Heisenberg model on the kagome 
lattice, Physical Review B 110 144437/1-29 (2024)2025. január 9. csütörtök, 
10.00
Wigner FK SZFI, 1. ép. 1. em. nagy előadóterem
Az előadás nyelve: magyar
Minden érdeklődőt szívesen látunk!
Nagy Attilaszfi-seminar AT wigner.hun-ren.hu