659 research outputs found
Evolution of Magnetism in Single-Crystal Honeycomb Iridates
We report the successful synthesis of single-crystals of the layered iridate,
(NaLi)IrO, , and a thorough study of
its structural, magnetic, thermal and transport properties. The new compound
allows a controlled interpolation between NaIrO and LiIrO,
while maintaing the novel quantum magnetism of the honeycomb Ir planes.
The measured phase diagram demonstrates a dramatic suppression of the N\'eel
temperature, , at intermediate suggesting that the magnetic order in
NaIrO and LiIrO are distinct, and that at , the
compound is close to a magnetically disordered phase that has been sought after
in NaIrO and LiIrO. By analyzing our magnetic data with a
simple theoretical model we also show that the trigonal splitting, on the
Ir ions changes sign from NaIrO and LiIrO, and the
honeycomb iridates are in the strong spin-orbit coupling regime, controlled by
\jeff=1/2 moments.Comment: updated version with more dat
Doping Evolution of Magnetic Order and Magnetic Excitations in (SrLa)IrO
We use resonant elastic and inelastic X-ray scattering at the Ir- edge
to study the doping-dependent magnetic order, magnetic excitations and
spin-orbit excitons in the electron-doped bilayer iridate
(SrLa)IrO (). With increasing
doping , the three-dimensional long range antiferromagnetic order is
gradually suppressed and evolves into a three-dimensional short range order
from to , followed by a transition to two-dimensional short range
order between and . Following the evolution of the
antiferromagnetic order, the magnetic excitations undergo damping, anisotropic
softening and gap collapse, accompanied by weakly doping-dependent spin-orbit
excitons. Therefore, we conclude that electron doping suppresses the magnetic
anisotropy and interlayer couplings and drives
(SrLa)IrO into a correlated metallic state hosting
two-dimensional short range antiferromagnetic order and strong
antiferromagnetic fluctuations of moments, with
the magnon gap strongly suppressed.Comment: 6 Pages, 3 Figures, with supplementary in Sourc
Signatures of a pair density wave at high magnetic fields in cuprates with charge and spin orders
In underdoped cuprates, the interplay of the pseudogap, superconductivity,
and charge and spin ordering can give rise to exotic quantum states, including
the pair density wave (PDW), in which the superconducting (SC) order parameter
is oscillatory in space. However, the evidence for a PDW state remains
inconclusive and its broader relevance to cuprate physics is an open question.
To test the interlayer frustration, the crucial component of the PDW picture,
we performed transport measurements on LaEuSrCuO
and LaNdSrCuO, cuprates with "striped" spin and
charge orders, in perpendicular magnetic fields (), and also with an
additional field applied parallel to CuO layers (). We
detected several phenomena predicted to arise from the existence of a PDW,
including an enhancement of interlayer SC phase coherence with increasing
. Our findings are consistent with the presence of local, PDW
pairing correlations that compete with the uniform SC order at , where is the SC transition temperature,
and become dominant at intermediate as . These data
also provide much-needed transport signatures of the PDW in the regime where
superconductivity is destroyed by quantum phase fluctuations.Comment: This is a pre-print of an article published in Nature Communications.
The final authenticated version is available online at:
https://doi.org/10.1038/s41467-020-17138-
Magnetic field reveals vanishing Hall response in the normal state of stripe-ordered cuprates
The origin of the weak insulating behavior of the resistivity, i.e.
, revealed when magnetic fields () suppress
superconductivity in underdoped cuprates has been a longtime mystery.
Surprisingly, the high-field behavior of the resistivity observed recently in
charge- and spin-stripe-ordered La-214 cuprates suggests a metallic, as opposed
to insulating, high-field normal state. Here we report the vanishing of the
Hall coefficient in this field-revealed normal state for all
, where is the zero-field
superconducting transition temperature. Our measurements demonstrate that this
is a robust fundamental property of the normal state of cuprates with
intertwined orders, exhibited in the previously unexplored regime of and
. The behavior of the high-field Hall coefficient is fundamentally different
from that in other cuprates such as YBaCuO and
YBaCuO, and may imply an approximate particle-hole symmetry that
is unique to stripe-ordered cuprates. Our results highlight the important role
of the competing orders in determining the normal state of cuprates.Comment: This is a post-peer-review, precopyedit version of an article
published in Nature Communications. The final authenticated version is
available online at: https://doi.org/10.1038/s41467-021-24000-
Effect of Consecutive Cut and Vegetation Stage on Cncps Protein Fractions in Alfalfa (Medicago Sativa L.)
Crude protein (CP) of forages can be separated into fractions of differentiated abilities to provide available amino acids in the lower gut of ruminants. This knowledge is critical to develop feeding systems and to predict animal responses. The objective of this research was to asses whether CP concentrations and the relative proportion of CP fractions by CNCPS in alfalfa (Medicago sativa L.) cv K-28 were affected by different cuts and vegetation stages. Fraction B2, which represents true protein of intermediate ruminal degradation rate, was the largest single fraction in all cuts except in the third cut. Soluble fraction A was less than 400 g kg-1 CP in all cuts except in the third cut, while the unavailable fraction C ranged from 56 g kg-1 CP in the first cut to 134.8 g kg-1 CP in the fourth cut. The remaining fraction B3 (true protein of very low degradation rate) only represented less than 60 g kg-1 of total CP. Results showed that undegraded dietary protein represented a small proportion of total CP in alfalfa from the first to the fourth cut
Lattice-Tuned Magnetism of Ru\u3csup\u3e4+\u3c/sup\u3e(4\u3cem\u3ed\u3c/em\u3e\u3csup\u3e4\u3c/sup\u3e) Ions in Single Crystals of the Layered Honeycomb Ruthenates Li\u3csub\u3e2\u3c/sub\u3eRuO\u3csub\u3e3\u3c/sub\u3e and Na\u3csub\u3e2\u3c/sub\u3eRuO\u3csub\u3e3\u3c/sub\u3e
We synthesize and study single crystals of the layered honeycomb lattice Mott insulators Na2RuO3 and Li2RuO3 with magnetic Ru4+(4d4) ions. The newly found Na2RuO3 features a nearly ideal honeycomb lattice and orders antiferromagnetically at 30 K. Single crystals of Li2RuO3 adopt a honeycomb lattice with either C2/m or more distorted P21/m below 300 K, depending on detailed synthesis conditions. We find that Li2RuO3 in both structures hosts a well-defined magnetic state, in contrast to the singlet ground state found in polycrystalline Li2RuO3. A phase diagram generated based on our results uncovers a new, direct correlation between the magnetic ground state and basal-plane distortions in the honeycomb ruthenates
Lattice-Tuned Magnetism of Ru4+(4d4) Ions in Single-Crystals of the Layered Honeycomb Ruthenates: Li2RuO3 and Na2RuO3
We synthesize and study single crystals of the layered honeycomb lattice Mott
insulators Na2RuO3 and Li2RuO3 with magnetic Ru4+(4d4) ions. The newly found
Na2RuO3 features a nearly ideal honeycomb lattice and orders
antiferromagnetically at 30 K. Single-crystals of Li2RuO3 adopt a honeycomb
lattice with either C2/m or more distorted P21/m below 300 K, depending on
detailed synthesis conditions. We find that Li2RuO3 in both structures hosts a
well-defined magnetic state, in contrast to the singlet ground state found in
polycrystalline Li2RuO3. A phase diagram generated based on our results
uncovers a new, direct correlation between the magnetic ground state and
basal-plane distortions in the honeycomb ruthenates.Comment: 4 figures, accepted for publication in Phys. Rev.
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