64 research outputs found
Ground-state phase diagram of an anisotropic spin- model on the triangular lattice
Motivated by the recent experiment on a rare-earth material YbMgGaO [Y.
Li \textit{et al.}, Phys. Rev. Lett. \textbf{115}, 167203 (2015)], which found
that the ground state of YbMgGaO is a quantum spin liquid, we study the
ground-state phase diagram of an anisotropic spin- model that was proposed
to describe YbMgGaO. Using the density-matrix renormalization group method
in combination with the exact diagonalization, we calculate a variety of
physical quantities, including the ground-state energy, the fidelity, the
entanglement entropy and spin-spin correlation functions. Our studies show that
in the quantum phase diagram there is a phase and two distinct
stripe phases. The transitions from the two stripe phases to the
phase are of the first order. However, the transition between the two stripe
phases is not the first order, which is different from its classical
counterpart. Additionally, we find no evidence for a quantum spin liquid in
this model. Our results suggest that additional terms may be also important to
model the material YbMgGaO. These findings will stimulate further
experimental and theoretical works in understanding the quantum spin liquid
ground state in YbMgGaO.Comment: minor change
Eficacia del esquema inmunosupresor con MTORI en la preservación de la función renal en el paciente trasplantado hepático
The evolution of magnetic structure driven by a synthetic spin-orbit coupling in two-component Bose-Hubbard model
We study the evolution of magnetic structure driven by a synthetic spin-orbit
coupling in a one-dimensional two-component Bose-Hubbard model. In addition to
the Mott insulator-superfluid transition, we found in Mott insulator phases a
transition from a gapped ferromagnetic phase to a gapless chiral phase by
increasing the strength of spin-orbit coupling. Further increasing the
spin-orbit coupling drives a transition from the gapless chiral phase to a
gapped antiferromagnetic phase. These magnetic structures persist in superfluid
phases. In particular, in the chiral Mott insulator and chiral superfluid
phases, incommensurability is observed in characteristic correlation functions.
These unconventional Mott insulator phase and superfluid phase demonstrate the
novel effects arising from the competition between the kinetic energy and the
spin-orbit coupling.Comment: 9 fig; English polished, note adde
Ground-state phase diagram of the frustrated spin-1/2 two-leg honeycomb ladder
We investigate a spin- two-leg honeycomb ladder with frustrating
next-nearest-neighbor (NNN) coupling along the legs, which is equivalent to two
- spin chains coupled with at odd rungs. The full parameter
region of the model is systematically studied using conventional and infinite
density-matrix renormalization group as well as bosonization. The rich phase
diagram consists of five distinct phases: A Haldane phase, a NNN-Haldane phase
and a staggered dimer phase when ; a rung singlet phase and a
columnar dimer phase when . An interesting reentrant behavior
from the dimerized phase into the Haldane phase is found as the frustration
increases. The universalities of the critical phase transitions are fully
analyzed. Phase transitions between dimerized and disordered phases belong to
the two-dimensional Ising class with central charge . The transition
from the Haldane phase to NNN-Haldane phase is of a weak topological first
order, while the continuous transition between the Haldane phase and rung
singlet phase has central charge .Comment: 14 pages, 17 figures, for latest version and additional information
see https://www.physik.uni-kl.de/eggert/papers/index.htm
Theoretical Investigation of the Black-body Zeeman Shift for Microwave Atomic Clocks
With the development of microwave atomic clocks, the Zeeman shifts for the
spectral lines of black-body radiation need to be investigated carefully. In
this Letter, the frequency shifts of hyperfine splittings of atomic ground
states due to the magnetic field of black-body radiation are reported. The
relative frequency shifts of different alkali atoms and alkali-like ions, which
could be candidates of microwave atomic clocks, were calculated. The results
vary from to
for different atoms considered. These
results are consistent with previous work but with greater precision, detailed
derivations, and a clear physical picture
Critical entanglement of XXZ Heisenberg chains with defects
We study the entanglement properties of anisotropic open spin one-half
Heisenberg chains with a modified central bond. The entanglement entropy
between the two half-chains is calculated with the density-matrix
renormalization method (DMRG).We find a logarithmic behaviour with an effective
central charge c' varying with the length of the system. It flows to one in the
ferromagnetic region and to zero in the antiferromagnetic region of the model.
In the XX case it has a non-universal limit and we recover previous results.Comment: 8 pages, 15 figure
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