86 research outputs found
^{31}P and ^{75}As NMR evidence for a residual density of states at zero energy in superconducting BaFe_2(As_{0.67}P_{0.33})_2
^{31}P and ^{75}As NMR measurements were performed in superconducting
BaFe_2(As_{0.67}P_{0.33})_2 with T_c = 30 K. The nuclear-spin-lattice
relaxation rate T_1^{-1} and the Knight shift in the normal state indicate the
development of antiferromagnetic fluctuations, and T_1^{-1} in the
superconducting (SC) state decreases without a coherence peak just below T_c,
as observed in (Ba_{1-x}K_{x})Fe_2As_2. In contrast to other iron arsenide
superconductors, the T_1^{-1} \propto T behavior is observed below 4K,
indicating the presence of a residual density of states at zero energy. Our
results suggest that strikingly different SC gaps appear in
BaFe_2(As_{1-x}P_{x})_2 despite a comparable T_c value, an analogous phase
diagram, and similar Fermi surfaces to (Ba_{1-x}K_{x})Fe_2As_2.Comment: 4 pages, 5 figure
Identification of a Kitaev Quantum Spin Liquid by Magnetic Field Angle Dependence
Quantum spin liquids realize massive entanglement and fractional
quasiparticles with localized spins, proposed as an avenue for quantum science
and technology. In particular, topological quantum computations are suggested
in the non-abelian phase of Kitaev quantum spin liquid with Majorana fermions,
and detection of Majorana fermions is one of the most outstanding problems in
modern condensed matter physics. Here, we propose a concrete way to identify
the non-abelian Kitaev quantum spin liquid by magnetic field angle dependence.
Topologically protected critical lines exist on a plane of magnetic field
angles, and their shapes are determined by microscopic Hamiltonian information.
A chiral spin operator plays a key role to detect the critical lines varying
with magnetic field angles, and experimental criteria for the non-abelian spin
liquid state are provided. Our proposal may be employed as a new route to probe
a non-abelian quantum spin liquid in addition to the half-quantization of
thermal Hall conductivity.Comment: 12 pages, 8 figures, 2 table
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