Equilibrium and nonequilibrium dynamics of a hole in a bilayer antiferromagnet

Nyhegn，Jens H.1; Nielsen，Kristian K.1,2; Bruun，Georg M.1,3

2022-10-15

10.1103/PhysRevB.106.155160

Physical Review B   影响因子和分区

2469-9950

2469-9969

The dynamics of charge carriers in lattices of quantum spins is a long standing and fundamental problem. Recently, a new generation of quantum simulation experiments based on atoms in optical lattices has emerged that gives unprecedented insights into the detailed spatial and temporal dynamics of this problem, which compliments earlier results from condensed matter experiments. Focusing on observables accessible in these new experiments, we explore here the equilibrium as well as nonequilibrium dynamics of a mobile hole in two coupled antiferromagnetic spin lattices. Using a self-consistent Born approximation, we calculate the spectral properties of the hole in the bilayer and extract the energy bands of the quasiparticles, corresponding to magnetic polarons that are either symmetric or antisymmetric under layer exchange. These two kinds of polarons are degenerate at certain momenta due to the antiferromagnetic symmetry, and we, furthermore, examine how the momentum of the ground-state polaron depends on the interlayer coupling strength. The long time dynamics of a hole initially created in one layer is shown to be characterized by oscillations between the two layers with a frequency given by the energy difference between the symmetric and the antisymmetric polaron. We finally demonstrate that the expansion velocity of a hole initially created at a given lattice site is governed by the ballistic motion of polarons for long times, and that it increases as a quantum phase transition to a disordered state is approached. While our linear spin wave theory does not include interlayer dimer correlations important close to the phase transition, this speedup is a physically robust prediction as it reflects the decreasing energy cost of hopping when the magnetic order decreases.

SCI

英语

通讯

WOS:000879247600003

PHYSICS

2-s2.0-85141303786

Scopus

1.Center for Complex Quantum Systems,Department of Physics and Astronomy,Aarhus University,Aarhus C,Ny Munkegade,DK-8000,Denmark
2.Max-Planck Institute for Quantum Optics,Garching,Hans-Kopfermann-Strasse 1,D-85748,Germany
3.Shenzhen Institute for Quantum Science and Engineering,Department of Physics,Southern University of Science and Technology,Shenzhen,518055,China

Nyhegn，Jens H.,Nielsen，Kristian K.,Bruun，Georg M.. Equilibrium and nonequilibrium dynamics of a hole in a bilayer antiferromagnet[J]. Physical Review B,2022,106(15).

Nyhegn，Jens H.,Nielsen，Kristian K.,&Bruun，Georg M..(2022).Equilibrium and nonequilibrium dynamics of a hole in a bilayer antiferromagnet.Physical Review B,106(15).

Nyhegn，Jens H.,et al."Equilibrium and nonequilibrium dynamics of a hole in a bilayer antiferromagnet".Physical Review B 106.15(2022).