101 research outputs found
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
Softened magnetic excitations in the s = 3/2 distorted triangular antiferromagnet alpha-CaCr2O4
The spin dynamics and magnetic excitations of the slightly distorted
triangular s = 3/2 system alpha-CaCr2O4 are investigated by means of Raman
spectroscopy and electron spin resonance (ESR) to elucidate its peculiar
magnetic properties. Two-magnon excitations in circular RL symmetry show a
multi-maximum structure with a dominant spectral weight at low energies. The
temperature dependence of the ESR linewidth is described by a critical
broadening DeltaHpp(T) ~ (T - T_N)^{-p} with the exponent p = 0.30(3) - 0.38(5)
for temperatures above T_N = 42.6 K. The exponent is much smaller than that of
other s = 3/2 triangular lattices. This is ascribed to soft roton-like modes,
indicative of the instability of a helical 120{\deg} phase. As an origin we
discuss a complex spin topology formed by four inequivalent nearest neighbor
and sizable next-nearest neighbor interactions.Comment: 7 pages, 4 figure
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