8,260 research outputs found
Antiferromagnetic Order in Pauli Limited Unconventional Superconductors
We develop a theory of the coexistence of superconductivity (SC) and
antiferromagnetism (AFM) in CeCoIn5. We show that in Pauli-limited nodal
superconductors the nesting of the quasi-particle pockets induced by Zeeman
pair-breaking leads to incommensurate AFM with the moment normal to the field.
We compute the phase diagram and find a first order transition to the normal
state at low temperatures, absence of normal state AFM, and coexistence of SC
and AFM at high fields, in agreement with experiments. We also predict the
existence of a new double-Q magnetic phase
Spin Supersolid in Anisotropic Spin-One Heisenberg Chain
We consider an S=1 Heisenberg chain with strong exchange (Delta) and
single--ion uniaxial anisotropy (D) in a magnetic field (B) along the symmetry
axis. The low energy spectrum is described by an effective S=1/2 XXZ model that
acts on two different low energy sectors for a given window of fields. The
vacuum of each sector exhibits Ising-like antiferromagnetic ordering that
coexists with the finite spin stiffness obtained from the exact solution of the
effective XXZ model. In this way, we demonstrate the existence of a spin
supersolid phase. We also compute the full Delta-B quantum phase diagram by
means of a quantum Monte Carlo simulation.Comment: 4+ pages, 2 fig
Vortex Viscosity in Magnetic Superconductors Due to Radiation of Spin Waves
In type-II superconductors that contain a lattice of magnetic moments,
vortices polarize the magnetic system inducing additional contributions to the
vortex mass, vortex viscosity, and vortex-vortex interaction. Extra magnetic
viscosity is caused by radiation of spin waves by a moving vortex. Like in the
case of Cherenkov radiation, this effect has a characteristic threshold
behavior and the resulting vortex viscosity may be comparable to the well-known
Bardeen-Stephen contribution. The threshold behavior leads to an anomaly in the
current-voltage characteristics, and a drop in dissipation for a current
interval that is determined by the magnetic excitation spectrum.Comment: 4 pages, 1 figur
Hamiltonian Reduction and the Construction of q-Deformed Extensions of the Virasoro Algebra
In this paper we employ the construction of Dirac bracket for the remaining
current of deformed Kac-Moody algebra when constraints similar to
those connecting the -WZW model and the Liouville theory are imposed and
show that it satisfy the q-Virasoro algebra proposed by Frenkel and
Reshetikhin. The crucial assumption considered in our calculation is the
existence of a classical Poisson bracket algebra induced, in a consistent
manner by the correspondence principle, mapping the quantum generators into
commuting objects of classical nature preserving their algebra.Comment: 6 pages, late
Electron Spin Resonance of SrCu2(BO3)2 at High Magnetic Field
We calculate the electron spin resonance (ESR) spectra of the
quasi-two-dimensional dimer spin liquid SrCu2(BO3)2 as a function of magnetic
field B. Using the standard Lanczos method, we solve a Shastry-Sutherland
Hamiltonian with additional Dzyaloshinsky-Moriya (DM) terms which are crucial
to explain different qualitative aspects of the ESR spectra. In particular, a
nearest-neighbor DM interaction with a non-zero D_z component is required to
explain the low frequency ESR lines for B || c. This suggests that crystal
symmetry is lowered at low temperatures due to a structural phase transition.Comment: 4 pages, 4 b&w figure
Characterization in bi-parameter space of a non-ideal oscillator
The authors thank scientific agencies CAPES, CNPq (112952/2015-1), and FAPESP (2011/ 19269-11). M. S. Baptista also thanks EPSRC (EP/I03 2606/1).Peer reviewedPostprin
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