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Low-energy spin dynamics of orthoferrites AFeO<sub>3</sub> (A = Y, La, Bi)
Park, Kisoo,Sim, Hasung,Leiner, Jonathan C,Yoshida, Yoshiyuki,Jeong, Jaehong,Yano, Shin-ichiro,Gardner, Jason,Bourges, Philippe,Klicpera, Milan,Sechovský,, Vladimí,r,Boehm, Martin,Park, Je IOP 2018 Journal of physics, an Institute of Physics journa Vol.30 No.23
<P>YFeO<SUB>3</SUB> and LaFeO<SUB>3</SUB> are members of the rare-earth orthoferrites family with <I>Pbnm</I> space group. Using inelastic neutron scattering, the low-energy spin excitations have been measured around the magnetic Brillouin zone center. Splitting of magnon branches and finite magnon gaps (∼2 meV) are observed for both compounds, where the Dzyaloshinsky–Moriya interactions account for most of this gap with some additional contribution from single-ion anisotropy. We also make comparisons with multiferroic BiFeO<SUB>3</SUB> (<I>R3c</I> space group), in which similar behavior was observed. By taking into account all relevant local Dzyaloshinsky–Moriya interactions, our analysis allows for the precise determination of all experimentally observed parameters in the spin-Hamiltonian. We find that different properties of the <I>Pbnm</I> and <I>R3c</I> space group lead to the stabilization of a spin cycloid structure in the latter case but not in the former, which explains the difference in the levels of complexity of magnon band structures for the respective compounds.</P>
Masatoshi Sato,Yoshiaki Kobayashi,Takayuki Kawamata,Yukio Yasui,Kazunori Suzuki,M. Itoh,Ryoichi Kajimoto,Kazuhiko Ikeuchi,M. Arai,Phillipe Bourges 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12
To identify the superconducting symmetry of Fe-based superconductors, we studied effects ofnonmagnetic-impurities on Tc, magnetic excitation spectra 00 and NMR 1/T1 − T curve, whichare sensitive to the relative signs between the order parameters on the disconnected Fermi surfacesin reciprocal space, because the symmetry is closely connected with the pairing mechanism:If the signs are opposite (symmetry S±), the mechanism is considered to be a magneticone, but when the signs are the same (symmetry S++), a novel mechanism is plausible becausethe ordinary phonon mechanism cannot realize the Tc value as high as 55 K found in Ln1111(Ln=lanthanide). Results are as follows: (a) The very small rates of Tc-suppression by impurityatoms M of LnFe1−yMyAs0.89−xF0.11+x (M=Ni, Co, Ru) can be explained only by S++. (b) The00-data for Ba(Fe, Co)2As2 (Tc 23 K) and Ca-Fe-Pt-As crystals seem to be well explained byS++ rather than by S±. (c) The nuclear magnetic resonance data can be consistently understoodby S++, too. These results suggest the S++ symmetry and a novel pairing mechanism, which canbe considered to be related to the elastic softening of C66 induced by the orbital fluctuation of thesystem.
Josefina Consuelo Morales-Guerrero,Reina Rosas-Romero,Ma Amanda Mariscal-Gálvez,Fabiola Ayala-Alcántara,Héctor Bourges-Rodríguez 한국식품영양과학회 2023 Journal of medicinal food Vol.26 No.6
Correct nutrition is important for keeping good health; to attain that, the diet has to include vegetables such as quelites. The objective of this study was to determine the glycemic index (GI) and glycemic load (GL) of rice and a tamal prepared with and without two species of quelites: “alache” (Anoda cristata) and “chaya” (Cnidoscolus aconitifolius). The GI was measured in 10 healthy subjects, 7 women and 3 men, with the following mean metrics: age, 23 years old; body weight, 61.3 kg; height, 1.65 m; body mass index, 22.7 kg/m2; and basal glycemia, 77.4 mg/dL. Capillary blood samples were collected within 2 h after the meal. White rice (rice with no quelites) had a GI of 75.35 ± 15.6 and a GL of 36.17 ± 7.8; rice with alache had a GI of 33.74 ± 5.85 and a GL 33.74 ± 1.85. White tamal had a GI of 57.33 ± 10.23 and a GC of 26.65 ± 5.12; tamal with chaya had a GI of 46.73 ± 22.1 and a GL of 23.36 ± 11. The GI and GL values recorded for the combination of quelites with rice and tamal confirmed that quelites could be a good alternative for healthy diets.
Li, Y.,Balé,dent, V.,Bariš,ić,, N.,Cho, Y.,Fauqué,, B.,Sidis, Y.,Yu, G.,Zhao, X.,Bourges, P.,Greven, M. Macmillan Publishers Limited. All rights reserved 2008 Nature Vol.455 No.7211
The pseudogap region of the phase diagram is an important unsolved puzzle in the field of high-transition-temperature (high-T<SUB>c</SUB>) superconductivity, characterized by anomalous physical properties. There are open questions about the number of distinct phases and the possible presence of a quantum-critical point underneath the superconducting dome. The picture has remained unclear because there has not been conclusive evidence for a new type of order. Neutron scattering measurements for YBa<SUB>2</SUB>Cu<SUB>3</SUB>O<SUB>6+δ</SUB> (YBCO) resulted in contradictory claims of no and weak magnetic order, and the interpretation of muon spin relaxation measurements on YBCO and of circularly polarized photoemission experiments on Bi<SUB>2</SUB>Sr<SUB>2</SUB>CaCu<SUB>2</SUB>O<SUB>8+δ</SUB>(refs 12, 13) has been controversial. Here we use polarized neutron diffraction to demonstrate for the model superconductor HgBa<SUB>2</SUB>CuO<SUB>4+δ</SUB> (Hg1201) that the characteristic temperature T* marks the onset of an unusual magnetic order. Together with recent results for YBCO, this observation constitutes a demonstration of the universal existence of such a state. The findings appear to rule out theories that regard T* as a crossover temperature rather than a phase transition temperature. Instead, they are consistent with a variant of previously proposed charge-current-loop order that involves apical oxygen orbitals, and with the notion that many of the unusual properties arise from the presence of a quantum-critical point.