64 research outputs found
In- and out-of-plane field induced quantum spin-liquid states in a more ideal Kitaev material: BaCo(AsO)
Kitaev quantum spin liquids (QSLs) are exotic states of matter that are
predicted to host Majorana fermions and gauge flux excitations. However, so far
all known Kitaev QSL candidates are known to have appreciable non-Kitaev
interactions that pushes these systems far from the QSL regime. Using
time-domain terahertz spectroscopy (TDTS) we show that the honeycomb
cobalt-based Kitaev QSL candidate, BaCo(AsO), has dominant Kitaev
interactions. Due to only small non-Kitaev terms a magnetic continuum
consistent with Majorana fermions and the existence of a Kitaev QSL can be
induced by a small 4 T out-of-plane-magnetic field. Applying an even smaller
in-plane magnetic field 0.5 T suppresses the effects of the non-Kitaev
interactions and gives rise to a field induced intermediate state also
consistent with a QSL. These results may have fundamental impact for realizing
quantum computation. Our results demonstrate BaCo(AsO) as a far
more ideal version of Kitaev QSL compared with other candidates
Substitution of Ni for Fe in superconducting FeTeSe depresses the normal-state conductivity but not the magnetic spectral weight
We have performed systematic resistivity and inelastic neutron scattering
measurements on FeNiTeSe samples to study the
impact of Ni substitution on the transport properties and the low-energy (
12 meV) magnetic excitations. It is found that, with increasing Ni doping, both
the conductivity and superconductivity are gradually suppressed; in contrast,
the low-energy magnetic spectral weight changes little. Comparing with the
impact of Co and Cu substitution, we find that the effects on conductivity and
superconductivity for the same degree of substitution grow systematically as
the atomic number of the substituent deviates from that of Fe. The impact of
the substituents as scattering centers appears to be greater than any
contribution to carrier concentration. The fact that low-energy magnetic
spectral weight is not reduced by increased electron scattering indicates that
the existence of antiferromagnetic correlations does not depend on electronic
states close to the Fermi energy.Comment: 6 pages, 5 figure
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