2,951 research outputs found
Topological phase in topological Kondo insulator: topological insulator, Haldane-like phase and Kondo breakdown
We have simulated a half-filled -wave periodic Anderson model with
numerically exact projector quantum Monte Carlo technique, and the system is
indeed located in the Haldane-like state as detected in previous works on the
-wave Kondo lattice model, though the soluble non-interacting limit
corresponds to the conventional topological insulator. The
site-resolved magnetization in an open boundary system and strange correlator
for the periodic boundary have been used to identify the mentioned topological
states. Interestingly, the edge magnetization in the Haldane-like state is not
saturated to unit magnetic moment due to the intrinsic charge fluctuation in
our periodic Anderson-like model, which is beyond the description of the Kondo
lattice-like model in existing literature. The finding here underlies the
correlation driven topological state in this prototypical interacting
topological state of matter and naive use of non-interacting picture should be
taken care. Moreover, no trace of the surface Kondo breakdown at zero
temperature is observed and it is suspected that frustration-like interaction
may be crucial in inducing such radical destruction of Kondo screening. The
findings here may be relevant to our understanding of interacting topological
materials like topological Kondo insulator candidate SmB.Comment: 11 pages, 9 figures, accepted by EPJ
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Transversus abdominis plane block reduces remifentanil and propofol consumption, evaluated by closed-loop titration guided by bispectral index.
The present prospective, randomized, double-blind study aimed to determine the impact of transversus abdominis plane (TAP) block on propofol and remifentanil consumption, when administered by closed-loop titration guided by processed electroencephalography, i.e., bispectral index (BIS) values. Following institutional review board approval, 60 patients were scheduled for laparoscopic colectomy under general anesthesia. Patients were randomly assigned to receive bilateral TAP block with 20 ml 0.375% ropivacaine (TAP group) or 20 ml 0.9% saline [control (CON) group]. General anesthesia was maintained with propofol and remifentanil administration using closed-loop titration guided by BIS values. The primary outcome was perioperative propofol and remifentanil consumption. The secondary outcomes were hypertensive or hypotensive events requiring treatment, recovery time in PACU and time to first rescue analgesia following surgery. A total of 58 patients participated in the present study. At similar depths of anesthesia, as measured by BIS during the maintenance phase (45-55), patients who received TAP blocks required less propofol (4.2±1.3 vs. 5.5±1.6 mg/kg/h; P<0.001) and remifentanil (0.16±0.05 vs. 0.21±0.05 µg/kg/min; P<0.001). Time to extubation was significantly shorter in the TAP group (9.8±3.2 min) than in the CON group (14.2±4.9 min) (P<0.05). The requirement to treat hemodynamic change was also significantly lower (P<0.05). Pain score at 2 h after surgery was also significantly reduced in the TAP group compared with the CON group (P<0.05), whereas the time to first rescue analgesia was delayed in patients who received TAP block (P<0.05). Postoperative nausea and vomiting occurred at comparable rates in each group (P>0.05). In conclusion, TAP block combined with general anesthesia reduced propofol and remifentanil consumption, shortened time to tracheal extubation and promoted hemodynamic stability in laparoscopic colectomy
Universal linear-temperature resistivity: possible quantum diffusion transport in strongly correlated superconductors
The strongly correlated electron fluids in high temperature cuprate
superconductors demonstrate an anomalous linear temperature () dependent
resistivity behavior, which persists to a wide temperature range without
exhibiting saturation. As cooling down, those electron fluids lose the
resistivity and condense into the superfluid. However, the origin of the
linear- resistivity behavior and its relationship to the strongly correlated
superconductivity remain a mystery. Here we report a universal relation
, which bridges the slope of the
linear--dependent resistivity () to the London penetration depth
at zero temperature among cuprate superconductor
BiSrCaCuO and heavy fermion superconductors
CeCoIn, where is vacuum permeability, is the Boltzmann
constant and is the reduced Planck constant. We extend this scaling
relation to different systems and found that it holds for other cuprate,
pnictide and heavy fermion superconductors as well, regardless of the
significant differences in the strength of electronic correlations, transport
directions, and doping levels. Our analysis suggests that the scaling relation
in strongly correlated superconductors could be described as a hydrodynamic
diffusive transport, with the diffusion coefficient () approaching the
quantum limit , where is the quasi-particle effective
mass.Comment: 8 pages, 2 figures, 1 tabl
Correlated metallic state in honeycomb lattice: Orthogonal Dirac semimetal
A novel gapped metallic state coined orthogonal Dirac semimetal is proposed
in the honeycomb lattice in terms of slave-spin representation of
Hubbard model. This state corresponds to the disordered phase of slave-spin and
has the same thermaldynamical and transport properties as usual Dirac semimetal
but its singe-particle excitation is gapped and has nontrivial topological
order due to the gauge structure. The quantum phase transition from
this orthogonal Dirac semimetal to usual Dirac semimetal is described by a
mean-field decoupling with complementary fluctuation analysis and its
criticality falls into the universality class of 2+1D Ising model while a large
anomalous dimension for the physical electron is found at quantum critical
point (QCP), which could be considered as a fingerprint of our fractionalized
theory when compared to other non-fractionalized approaches. As byproducts, a
path integral formalism for the slave-spin representation of Hubbard
model is constructed and possible relations to other approaches and the
sublattice pairing states, which has been argued to be a promising candidate
for gapped spin liquid state found in the numerical simulation, are briefly
discussed. Additionally, when spin-orbit coupling is considered, the
instability of orthogonal Dirac semimetal to the fractionalized quantum spin
Hall insulator (fractionalized topological insulator) is also expected. We hope
the present work may be helpful for future studies in slave-spin theory
and related non-Fermi liquid phases in honeycomb lattice.Comment: 12 pages,no figures, more discussions added. arXiv admin note: text
overlap with arXiv:1203.063
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