90 research outputs found
Magnetization plateaux cascade in the frustrated quantum antiferromagnet CsCoBr
We have found an unusual competition of two frustration mechanisms in the 2D
quantum antiferromagnet CsCoBr. The key actors are the alternation of
single-ion planar anisotropy direction of the individual magnetic Co
ions, and their arrangement in a distorted triangular lattice structure. In
particular, the uniquely oriented Ising-type anisotropy emerges from the
competition of easy-plane ones, and for a magnetic field applied along this
axis one finds a cascade of five ordered phases at low temperatures. Two of
these phases feature magnetization plateaux. The low-field one is supposed to
be a consequence of a collinear ground state stabilized by the anisotropy,
while the other plateau bears characteristics of an "up-up-down" state
exclusive for lattices with triangular exchange patterns. Such coexistence of
the magnetization plateaux is a fingerprint of competition between the
anisotropy and the geometric frustration in CsCoBr.Comment: 10 pages, 8 figure
Electron Spin Resonance in a Spin-1/2 Heisenberg Strong-rung Ladder
Cu(CHN)Cl, a strong-rung spin-1/2 Heisenberg ladder compound,
is probed by means of electron spin resonance (ESR) spectroscopy in the
field-induced gapless phase above . The temperature dependence of the
ESR linewidth is analyzed in the quantum field theory framework, suggesting
that the anisotropy of magnetic interactions plays a crucial role, determining
the peculiar low-temperature ESR linewidth behavior. In particular, it is
argued that the uniform Dzyaloshinskii-Moriya interaction (which is allowed on
the bonds along the ladder legs) can be the source of this behavior in
Cu(CHN)Cl
Modes of magnetic resonance in the spin liquid phase of Cs2CuCl4
We report the observation of a frequency shift and splitting of the electron
spin resonance (ESR) mode of the low-dimensional S=1/2 frustrated
antiferromagnet Cs2CuCl4 in the spin-correlated state below the Curie-Weiss
temperature 4 K but above the ordering temperature 0.62 K. The shift and
splitting exhibit strong anisotropy with respect to the direction of the
applied magnetic field and do not vanish in zero field. The low-temperature
evolution of spin resonance response is a result of the specific modification
of one-dimensional spinon continuum under the action of the uniform
Dzyaloshinskii-Moriya interaction (DM) within the spin chains. Parameters of
the uniform DM interaction are derived from the experiment.Comment: 10 pages, 12 figure
Confinement of fractional excitations in a triangular lattice antiferromagnet
High-resolution neutron and THz spectroscopies are used to study the magnetic
excitation spectrum of CsCoBr, a distorted-triangular-lattice
antiferromagnet with nearly XY-type anisotropy. What was previously thought of
as a broad excitation continuum [Phys. Rev. Lett. 129, 087201 (2022)] is shown
to be a series of dispersive bound states reminiscent of "Zeeman ladders" in
quasi-one-dimensional Ising systems. At wave vectors where inter-chain
interactions cancel at the Mean Field level, they can indeed be interpreted as
bound finite-width kinks in individual chains. Elsewhere in the Brillouin zone
their true two-dimensional structure and propagation are revealed.Comment: 11 pages, 8 figure
Environmentally friendly organic synthesis using bismuth compounds. Bismuth(III) bromide catalyzed synthesis of substituted tetrahydroquinoline derivatives
Intramolecular Imino Diels−Alder Reaction: Progress toward the Synthesis of Uncialamycin
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