424 research outputs found
Gapped ground state in the zigzag pseudospin-1/2 quantum antiferromagnetic chain compound PrTiNbO6
We report a single-crystal study on the magnetism of the rare-earth compound
PrTiNbO that experimentally realizes the zigzag pseudospin-
quantum antiferromagnetic chain model. Random crystal electric field caused by
the site mixing between non-magnetic Ti and Nb, results in the
non-Kramers ground state quasi-doublet of Pr with the effective
pseudospin- Ising moment. Despite the antiferromagnetic intersite
coupling of about 4 K, no magnetic freezing is detected down to 0.1 K, whilst
the system approaches its ground state with almost zero residual spin entropy.
At low temperatures, a sizable gap of about 1 K is observed in zero field. We
ascribe this gap to off-diagonal anisotropy terms in the pseudospin
Hamiltonian, and argue that rare-earth oxides open an interesting venue for
studying magnetism of quantum spin chains.Comment: 11 pages, 10 figures, 1D correlated magnetism of non-Kramers Ising
quasi-doublets in PrTiNbO
Electrical transport and magnetic properties of the triangular-lattice compound ZrNiP
We report the first investigation of the electrical and magnetic properties
of the triangular-lattice compound ZrNiP (space group 6/).
The temperature evolution of electrical resistivity follows the
Bloch-Gr\"uneisen-Mott law, and exhibits a typically metallic behavior. No
transition is visible by both electrical and magnetic property measurements,
and nearly no magnetization is detected ( 0.002/Ni)
down to 1.8 K up to 7 T. The metallic and nonmagnetic characters are well
understood by the first-principles calculations for ZrNiP.Comment: 16 pages, 4 figure
Crystalline Electric Field Randomness in the Triangular Lattice Spin-Liquid YbMgGaO
We apply moderate-high-energy inelastic neutron scattering (INS) measurements
to investigate Yb crystalline electric field (CEF) levels in the
triangular spin-liquid candidate YbMgGaO. Three CEF excitations from the
ground-state Kramers doublet are centered at the energies = 39,
61, and 97\,meV in agreement with the effective \mbox{spin-1/2} -factors and
experimental heat capacity, but reveal sizable broadening. We argue that this
broadening originates from the site mixing between Mg and Ga
giving rise to a distribution of Yb--O distances and orientations and, thus, of
CEF parameters that account for the peculiar energy profile of the CEF
excitations. The CEF randomness gives rise to a distribution of the effective
spin-1/2 -factors and explains the unprecedented broadening of low-energy
magnetic excitations in the fully polarized ferromagnetic phase of YbMgGaO,
although a distribution of magnetic couplings due to the Mg/Ga disorder may be
important as well.Comment: Accepted in Phys. Rev. Let
Nearest-neighbor resonating valence bonds in YbMgGaO4
Since its proposal by Anderson, resonating valence bonds (RVB) formed by a
superposition of fluctuating singlet pairs have been a paradigmatic concept in
understanding quantum spin liquids (QSL). Here, we show that excitations
related to singlet breaking on nearest-neighbor bonds describe the high-energy
part of the excitation spectrum in YbMgGaO4, the effective spin-1/2 frustrated
antiferromagnet on the triangular lattice, as originally considered by
Anderson. By a thorough single-crystal inelastic neutron scattering (INS)
study, we demonstrate that nearest-neighbor RVB excitations account for the
bulk of the spectral weight above 0.5 meV. This renders YbMgGaO4 the first
experimental system where putative RVB correlations restricted to nearest
neighbors are observed, and poses a fundamental question of how complex
interactions on the triangular lattice conspire to form this unique many-body
state.Comment: To be published in Nature Communication
Crystalline Electric Field Randomness in the Triangular Lattice Spin-Liquid YbMgGaO
We apply moderate-high-energy inelastic neutron scattering (INS) measurements
to investigate Yb crystalline electric field (CEF) levels in the
triangular spin-liquid candidate YbMgGaO. Three CEF excitations from the
ground-state Kramers doublet are centered at the energies = 39,
61, and 97\,meV in agreement with the effective \mbox{spin-1/2} -factors and
experimental heat capacity, but reveal sizable broadening. We argue that this
broadening originates from the site mixing between Mg and Ga
giving rise to a distribution of Yb--O distances and orientations and, thus, of
CEF parameters that account for the peculiar energy profile of the CEF
excitations. The CEF randomness gives rise to a distribution of the effective
spin-1/2 -factors and explains the unprecedented broadening of low-energy
magnetic excitations in the fully polarized ferromagnetic phase of YbMgGaO,
although a distribution of magnetic couplings due to the Mg/Ga disorder may be
important as well.Comment: Accepted in Phys. Rev. Let
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