2,705 research outputs found
Phase diagram of Kondo-Heisenberg model on honeycomb lattice with geometrical frustration
We calculated the phase diagram of the Kondo-Heisenberg model on
two-dimensional honeycomb lattice with both nearest-neighbor and
next-nearest-neighbor antiferromagnetic spin exchanges, to investigate the
interplay between RKKY and Kondo interactions at presence of magnetic
frustration. Within a mean-field decoupling technology in slave-fermion
representation, we derived the zero-temperature phase diagram as a function of
Kondo coupling and frustration strength . The geometrical frustration
can destroy the magnetic order, driving the original antiferromagnetic (AF)
phase to non-magnetic valence bond state (VBS). In addition, we found two
distinct VBS. As is increased, a phase transition from AF to Kondo
paramagnetic (KP) phase occurs, without the intermediate phase coexisting AF
order with Kondo screening found in square lattice systems. In the KP phase,
the enhancement of frustration weakens the Kondo screening effect, resulting in
a phase transition from KP to VBS. We also found a process to recover the AF
order from VBS by increasing in a wide range of frustration strength. Our
work may provide deeper understanding for the phase transitions in
heavy-fermion materials, particularly for those exhibiting triangular
frustration
Design of three-dimensional photoelectric stylus micro-displacement measuring system
AbstractA novel method of three-dimensional photoelectric stylus micro-displacement measuring system was proposed in this paper. The micro-displacement which was got by cantilever was amplified through optics method, and experiment showed that the max error of measurement was 4um. The experimental prototype of micro-displacement measuring system was built and the working theory of micro-displacement measuring system was analyzed. The design of the main parts such as cantilever and probe of the system was completed and the parameters of the system were calibrated by using gauge blocks. The measurement experiment of thread and cylinder followed. The results showed the system has the capability of guiding experimental teaching task for undergraduates and completing middle or low accuracy measurement in the laboratory
Dyson-Schwinger Equations with a Parameterized Metric
We construct and solve the Dyson-Schwinger equation (DSE) of quark propagator
with a parameterized metric, which connects the Euclidean metric with the
Minkowskian one. We show, in some models, the Minkowskian vacuum is different
from the Euclidean vacuum. The usual analytic continuation of Green function
does not make sense in these cases. While with the algorithm we proposed and
the quark-gluon vertex ansatz which preserves the Ward-Takahashi identity, the
vacuum keeps being unchanged in the evolution of the metric. In this case,
analytic continuation becomes meaningful and can be fully carried out.Comment: 10 pages, 7 figures. To appear in Physical Review
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