11,232 research outputs found
Upper Pseudogap Phase: Magnetic Characterizations
It is proposed that the upper pseudogap phase (UPP) observed in the high-Tc
cuprates correspond to the formation of spin singlet pairing under the bosonic
resonating-valence-bond (RVB) description. We present a series of evidence in
support of such a scenario based on the calculated magnetic properties
including uniform spin susceptibility, spin-lattice and spin-echo relaxation
rates, which consistently show that strong spin correlations start to develop
upon entering the UPP, being enhanced around the momentum (\pi, \pi) while
suppressed around (0, 0). The phase diagram in the parameter space of doping
concentration, temperature, and external magnetic field, is obtained based on
the the bosonic RVB theory. In particular, the competition between the Zeeman
splitting and singlet pairing determines a simple relation between the
"critical" magnetic field, H_{PG}, and characteristic temperature scale, T0, of
the UPP. We also discuss the magnetic behavior in the lower pseudogap phase at
a temperature Tv lower than T0, which is characterized by the formation of
Cooper pair amplitude where the low-lying spin fluctuations get suppressed at
both (0, 0) and (\pi, \pi). Properties of the UPP involving charge channels
will be also briefly discussed.Comment: 11 pages, 5 figures, final version to appear in PR
Topological nodal states in circuit lattice
The search for artificial structure with tunable topological properties is an
interesting research direction of today's topological physics. Here, we
introduce a scheme to realize `topological semimetal states' with a
three-dimensional periodic inductor-capacitor (LC) circuit lattice, where the
topological nodal-line state and Weyl state can be achieved by tuning the
parameters of inductors and capacitors. A tight-binding-like model is derived
to analyze the topological properties of the LC circuit lattice. The key
characters of the topological states, such as the drumhead-like surface bands
for nodal-line state and the Fermi-arc-like surface bands for Weyl state, are
found in these systems. We also show that the Weyl points are stable with the
fabrication errors of electric devices.Comment: 4 figure
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