77 research outputs found
Tuning the magnetic and structural phase transitions of PrFeAsO via Fe/Ru spin dilution
Neutron diffraction and muon spin relaxation measurements are used to obtain
a detailed phase diagram of Pr(Fe,Ru)AsO. The isoelectronic substitution of Ru
for Fe acts effectively as spin dilution, suppressing both the structural and
magnetic phase transitions. The temperature of the tetragonal-orthorhombic
structural phase transition decreases gradually as a function of x. Slightly
below the transition temperature coherent precessions of the muon spin are
observed corresponding to static magnetism, possibly reflecting a significant
magneto-elastic coupling in the FeAs layers. Short range order in both the Fe
and Pr moments persists for higher levels of x. The static magnetic moments
disappear at a concentration coincident with that expected for percolation of
the J1-J2 square lattice model
Spin-dynamics of the low-dimensional magnet (CH3)2NH2CuCl3
Dimethylammonium copper (II) chloride (also known as DMACuCl3 or MCCL) is a
low dimensional S=1/2 quantum spin system proposed to be an alternating
ferro-antiferromagnetic chain with similar magnitude ferromagnetic (FM) and
antiferromagnetic (AFM) exchange interactions. Subsequently, it was shown that
the existing bulk measurements could be adequately modeled by considering
DMACuCl3 as independent AFM and FM dimer spin pairs. We present here new
inelastic neutron scattering measurements of the spin-excitations in single
crystals of DMACuCl3. These results show significant quasi-one-dimensional
coupling, however the magnetic excitations do not propagate along the expected
direction. We observe a band of excitations with a gap of 0.95 meV and a
bandwidth of 0.82 meV.Comment: 3 pages, 2 figures included in text, submitted to proceedings of
International Conference on Neutron Scattering, December 200
Anisotropy of thermal conductivity oscillations in relation to the Kitaev spin liquid phase
In the presence of external magnetic field, the Kitaev model could either
hosts gapped topological anyon or gapless Majorana fermions. In
-RuCl, the gapped and gapless cases are only separated by a
thirty-degree rotation of the in-plane magnetic field vector. The
presence/absence of the spectral gap is key for understanding the thermal
transport behavior in -RuCl. Here, we study the anisotropy of the
oscillatory features of thermal conductivity in -RuCl. We examine
the oscillatory features of thermal conductivities (k//a, k//b) with fixed
external fields and found distinct behavior for the gapped (B//a) and gapless
(B//b) scenarios. Furthermore, we track the evolution of thermal resistivity
() and its oscillatory features with the rotation of in-plane
magnetic fields from B//b to B//a. The thermal resistivity
display distinct rotational symmetries before and after the emergence of the
field induced Kitaev spin liquid phase. These experiment data suggest close
correlations between the oscillatory features of thermal conductivity, the
underlying Kitaev spin liquid phase and the fermionic excitation it holds
SpinWaves in the Frustrated Kagomé Lattice Antiferromagnet KFe\u3csub\u3e3\u3c/sub\u3e(OH)\u3csub\u3e6\u3c/sub\u3e(SO\u3csub\u3e4\u3c/sub\u3e)\u3csub\u3e2\u3c/sub\u3e
The spin wave excitations of the S = 5/2 kagomé lattice antiferromagnet KFe3(OH)6(SO4)2 have been measured using high-resolution inelastic neutron scattering. We directly observe a flat mode which corresponds to a lifted ‘‘zero energy mode,’’ verifying a fundamental prediction for the kagomé lattice. A simple Heisenberg spin Hamiltonian provides an excellent fit to our spin wave data. The antisymmetric Dzyaloshinskii-Moriya interaction is the primary source of anisotropy and explains the low-temperature magnetization and spin structure
The planar thermal Hall conductivity in the Kitaev magnet {\alpha}-RuCl3
We report detailed measurements of the Onsager-like planar thermal Hall
conductivity in -RuCl, a spin-liquid candidate of
topical interest. With the thermal current and magnetic field
(zigzag axis), the observed varies strongly
with temperature (1-10 K). The results are well-described by bosonic edge
excitations which evolve to topological magnons at large . Fits to
yield a Chern number and a band energy 1
meV, in agreement with sharp modes seen in electron spin-resonance experiments.
The bosonic character is incompatible with half-quantization of
.Comment: 7 pages, 3 figure
- …