923 research outputs found
Magnetic excitations, phase diagram and order-by-disorder in the extended triangular-lattice Hubbard model
The dynamical structure factor is an important observable of quantum magnets
but due to numerical and theoretical limitations, it remains a challenge to
make predictions for Hubbard-like models beyond one dimension. In this work, we
study the magnetic excitations of the triangular lattice Hubbard model
including next-nearest neighbor hopping. Starting from the 120 and
stripe magnetic orders we compute the magnon spectra within a self-consistent
random phase approximation. In the stripe phase, we generically find accidental
zero modes related to a classical degeneracy known from the corresponding
- Heisenberg model. We extend the order-by-disorder mechanism to
Hubbard systems and show how quantum fluctuations stabilize the stripe order.
In addition, the frustration-induced condensation of magnon modes allows us to
map out the entire phase diagram which is in remarkable agreement with recent
numerical works. We discuss connections to experiments on triangular lattice
compounds and the relation of our results to the proposed chiral spin liquid
phase
Prethermal nematic order and staircase heating in a driven frustrated Ising magnet with dipolar interactions
Many-body systems subject to a high-frequency drive can show intriguing
thermalization behavior. Prior to heating to a featureless infinite-temperature
state, these systems can spend an exponentially long time in prethermal phases
characterized by various kinds of order. Here, we uncover the rich
non-equilibrium phase diagram of a driven frustrated two-dimensional Ising
magnet with competing short-range ferromagnetic and long-range dipolar
interactions. We show that the ordered stripe and nematic phases, which appear
in equilibrium as a function of temperature, underpin subsequent prethermal
phases in a new multi-step heating process en route towards the ultimate heat
death. We discuss implications for experiments on ferromagnetic thin films and
other driving induced phenomena in frustrated magnets.Comment: 4 pages + 2 figure
Quantum liquids of the S=3/2 Kitaev honeycomb and related Kugel-Khomskii models
The Kitaev honeycomb model (KHM) is unique among the spin- Kitaev
models due to a massive ground state quasi-degeneracy that hampered previous
numerical and analytical studies. In a recent work~\cite{jin2022unveiling}, we
showed how an SO(6) Majorana parton mean-field theory of the isotropic
KHM explains the anomalous features of this Kitaev spin liquid (KSL) in terms
of an emergent low-energy Majorana flat band. Away from the isotropic limit,
the KSL generally displays a quadrupolar order with gapped or gapless
Majorana excitations, features that were quantitatively confirmed by DMRG
simulations. In this paper, we explore the connection between the KHM
with Kugel-Khomskii models and discover new exactly soluble examples for the
latter. We perform a symmetry analysis for the variational parton mean-field
\emph{Ans{\"a}tze} in the spin and orbital basis for different quantum liquid
phases of the KHM. Finally, we investigate a proposed time-reversal
symmetry breaking spin liquid induced by a {[}111{]} single ion anisotropy and
elucidate its topological properties as well as experimental signatures, e.g.
an unquantized thermal Hall response.Comment: 17 pages, 9 figure
Sound field separation method with single holographic surface based on particle velocity measurement
All the current sound field separation methods based on particle velocity are apply measurement surfaces or a single measurement surface with pressure-velocity. In order to acquire less measurement data and efficient calculation, a sound field separation method with single holographic surface based on particle velocity is proposed. According to the principle of equivalent sources near-field acoustical holography technique, this method can separate directly the sound filed information radiated by target source from coherent sound fields. Numerical simulation analyzed the results with different frequencies and signal-to-noise ratio (SNR). The results show that this method can separate the coherent sources accurately and efficiently
- …