4,977 research outputs found
Quantum phase transitions in the Kane-Mele-Hubbard model
We study the two-dimensional Kane-Mele-Hubbard model at half filling by means
of quantum Monte Carlo simulations. We present a refined phase boundary for the
quantum spin liquid. The topological insulator at finite Hubbard interaction
strength is adiabatically connected to the groundstate of the Kane-Mele model.
In the presence of spin-orbit coupling, magnetic order at large Hubbard U is
restricted to the transverse direction. The transition from the topological
band insulator to the antiferromagnetic Mott insulator is in the universality
class of the three-dimensional XY model. The numerical data suggest that the
spin liquid to topological insulator and spin liquid to Mott insulator
transitions are both continuous.Comment: 13 pages, 10 figures; final version; new Figs. 4(b) and 8(b
Comment on "Novel Superfluidity in a Trapped Gas of Fermi Atoms with Repulsive Interaction Loaded on an Optical Lattice"
In a recent letter Machida et al. [Phys. Rev. Lett. 93, 200402 (2004)]
concluded that in a trapped gas of fermions with repulsive interactions a
superfluid phase appears around the Mott-insulator at the center of the trap.
They base their conclusion on a negative binding energy, and a large weight for
a singlet formed by particles located at opposite sides of the Mott-insulator.
We show here that the observed effects are not related to superfluidity.Comment: Revtex file, 1 page, 1 figure, published versio
Robertsonian chromosome polymorphism found in a local herd of the Japanese Black cattle
International audienc
Midkine in Inflammation
The 13 kDa heparin-binding growth factor midkine (MK) was originally identified as a molecule involved in the orchestration of embryonic development. Recent studies provided evidence for a new role of MK in acute and chronic inflammatory processes. Accordingly, several inflammatory diseases including nephritis, arthritis, atherosclerosis, colitis, and autoimmune encephalitis have been shown to be alleviated in the absence of MK in animal models. Reduced leukocyte recruitment to the sites of inflammation was found to be one important mechanism attenuating chronic inflammation when MK was absent. Furthermore, MK was found to modulate expression of proinflammatory cytokines and the expansion of regulatory T-cells. Here, we review the current understanding of the role of MK in different inflammatory disorders and summarize the knowledge of MK biology
Mott Domains of Bosons Confined on Optical Lattices
In the absence of a confining potential, the boson Hubbard model in its
ground state is known to exhibit a superfluid to Mott insulator quantum phase
transition at commensurate fillings and strong on-site repulsion. In this
paper, we use quantum Monte Carlo simulations to study the ground state of the
one dimensional bosonic Hubbard model in a trap. We show that some, but not
all, aspects of the Mott insulating phase persist when a confining potential is
present. The Mott behavior is present for a continuous range of incommensurate
fillings, a very different situation from the unconfined case. Furthermore the
establishment of the Mott phase does not proceed via a quantum phase transition
in the traditional sense. These observations have important implications for
the interpretation of experimental results for atoms trapped on optical
lattices. Initial results show that, qualitatively, the same results persist in
higher dimensions.Comment: Revtex file, five figures, include
New Superconducting and Magnetic Phases Emerge on the Verge of Antiferromagnetism in CeIn
We report the discovery of new superconducting and novel magnetic phases in
CeIn on the verge of antiferromagnetism (AFM) under pressure () through
the In-nuclear quadrupole resonance (NQR) measurements. We have found a
-induced phase separation of AFM and paramagnetism (PM) without any trace
for a quantum phase transition in CeIn. A new type of superconductivity
(SC) was found in GPa to coexist with AFM that is magnetically
separated from PM where the heavy fermion SC takes place. We propose that the
magnetic excitations such as spin-density fluctuations induced by the
first-order magnetic phase transition might mediate attractive interaction to
form Cooper pairs.Comment: 4 pages, 4 EPS figures, submitted to J. Phys. Soc. Jp
- …