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61.
62.
J.A. Hodges P. Bonville A. Forget J.P. Sanchez P. Vulliet M. Rams K. Królas 《The European Physical Journal B - Condensed Matter and Complex Systems》2003,33(2):173-181
Using 170Yb and 155Gd M?ssbauer measurements down to ∼ 0.03 K, we have examined the semiconducting pyrochlore Yb2Mo2O7 where the Mo intra-sublattice interaction is anti-ferromagnetic and the metallic pyrochlore Gd2Mo2O7 where this interaction is ferromagnetic. Additional information was obtained from susceptibility, magnetisation and 172Yb perturbed angular correlation measurements. The microscopic measurements evidence lattice disorder which is important in
Yb2Mo2O7 and modest in Gd2Mo2O7. Magnetic irreversibilities occur at 17 K in Yb2Mo2O7 and at 75 K in Gd2Mo2O7 and below these temperatures the rare earths carry magnetic moments which are induced through couplings with the Mo sublattice.
In Gd2Mo2O7, we observe the steady state Gd hyperfine populations at 0.027 K are out of thermal equilibrium, indicating that Gd and Mo
spin fluctuations persist at very low temperatures. Frustration is thus operative in this essentially isotropic pyrochlore
where the dominant Mo intra-sublattice interaction is ferromagnetic.
Received 13 January 2003 Published online 4 June 2003
RID="a"
ID="a"e-mail: hodges@drecam.saclay.cea.fr 相似文献
63.
This article elucidates the pitfalls identified in the software package SIMPRE recently developed by Baldoví et al. (J. Comput. Chem. 2013, 34, 1961) for modeling the spectroscopic and magnetic properties of single ion magnets as well as single‐molecule magnets. Analysis of the methodology used therein reveals that the crystal field parameters (CFPs), expressed nominally in the Stevens formalism, exhibit features characteristic for the CFPs expressed in the Wybourne notation. The resemblance of the two types of CFPs introduces a serious confusion that may lead to wrong comparisons of the CFPs taken from various sources. To clarify this confusion, the properties of the CFPs ( , ) associated with the Stevens operators ( X = S , J , or L ), which belong to the class of the tesseral‐tensor operators, are contrasted with those of the CFPs Bkq associated with the Wybourne operators , which belong to the class of the spherical‐tensor operators. Importantly, the confused properties of Stevens and Wybourne operators may bear on reliability of SIMPRE calculations. To consider this question independent calculations are carried out using the complete approach and compared with those of the restricted approach utilized earlier. It appears that the numerical results of the package SIMPRE are formally acceptable, however, the meaning of the CFPs must be properly reformulated. Several other conceptual problems arising from misinterpretations of the crucial notions and the CFP notations identified therein are also discussed and clarified. © 2014 Wiley Periodicals, Inc. 相似文献
64.
Yu-Jia Sun 《中国物理 B》2021,30(11):117104-117104
Ultrathin van der Waals (vdW) magnets provide a possibility to access magnetic ordering in the two-dimensional (2D) limit, which are expected to be applied in the spintronic devices. Raman spectroscopy is a powerful characterization method to investigate the spin-related properties in 2D vdW magnets, including magnon and spin-lattice interaction, which are hardly accessible by other optical methods. In this paper, the recent progress of various magnetic properties in 2D vdW magnets studied by Raman spectroscopy is reviewed, including the magnetic transition, spin-wave, spin-lattice interaction, symmetry tuning induced by spin ordering, and nonreciprocal magneto-phonon Raman scattering. 相似文献
65.
采用MonteCarlo方法对由异类自旋组成混合Heisenberg自旋体系进行了数值计算,以模拟和预测基于交换耦合模型纳米双相(硬磁软磁)磁性体系的磁性.区别于以往所报道的那些直接针对硬磁NdFeB与软磁纳米αFe复合磁体的微磁学计算工作,着眼于符合Heisenberg模型的两类完全不同的原子自旋集团(硬磁自旋和软磁自旋)之间的直接交换耦合作用,模拟计算了由这两类自旋组成的复合自旋体系的内禀矫顽力Hc、剩余磁化强度Mr、最大磁能级(M×H)max等宏观磁性参量随软磁自旋集团的尺度和体积百分比、两类自旋集
关键词:
Heisenberg模型
MonteCarlo模拟
纳米复合磁体
Nd-Fe-B 相似文献
66.
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper. 相似文献
67.
BHOWMICK Indrani HARRIS T. David DECHAMBENOIT Pierre HILLARD Elizabeth A. PICHON Cline JEON Ie-Rang CLéRAC Rodolphe 《中国科学:化学(英文版)》2012,(6):1004-1011,1192,1197
Three new cyanido-bridged heterometallic ReIVNiII and ReIVCuII one-dimensional systems were synthesized and extensively characterized both structurally and magnetically. Single-crystal X-ray diffraction analysis revealed that these compounds display a common topology, with chains composed of alternating [ReⅣCl4(CN)2]2- and [MⅡ(cyclam)]2+ (M = Ni in 1, Cu in 2) or [CuⅡ(N,N′-dimethylcyclam)]2+ (in 3) building units. Two different chain orientations with a tilt angle of ca. 51° to 55° are present in the crystal packing of these compounds. The magnetic susceptibility measurements suggest the presence of intrachain ferromagnetic interactions between the S = 3/2 ReIV centers and the 3d metal ions: S = 1 NiII or S = 1/2 CuII. At low temperature, a three-dimensional ordered magnetic phase induced by interchain antiferromagnetic interactions (antiferromagnetic for 1 and 2; canted antiferromagnetic for 3) is detected for the three compounds. 相似文献
68.
69.
Zhipeng Hou Jinbao Zhang Shifeng Xu Chunji Wu Jingjing Zhang Zihan Wang Kunlong Yang Wenquan Wang Xiaobo Du Feng Su 《Journal of magnetism and magnetic materials》2012
The phases, microstructure, and magnetic properties of Co80Zr18−xNbxB2 (x=1, 2, 3, and 4) melt-spun ribbons were investigated. The small substitution of Nb for Zr in the Co–Zr–B melt-spun ribbons resulted in the improvement of magnetic properties, especially the coercivity. The main effect of added Nb on the coercovity of Co–Zr–Nb–B melt-spun ribbons, originated from modification of the grain size of Co11Zr2 phase. The coercivity of the Co–Zr–Nb–B melt-spun ribbons depends on the annealing temperature. The optimal magnetic properties of Hc=5.1 kOe, and (BH)max=3.4 MGOe were obtained in the Co80Zr15Nb3B2 melt-spun ribbons annealed at 600 °C for 3 min. 相似文献
70.
The single domain size of BaFe12O19 powder with crystallite sizes less than 200 nm was produced using a citric acid precursor method. Fe3+ and Ba2+, in a molar ratio of 12, were chelated by COOH− in an aqueous solution. After ethylene glycol additions, esterification, dehydration, and calcination led to the formation of ester-derived BaFe12O19 powder. High pH and/or high citric acid contents in the starting solution are required to complete chelate metallic ions in the solution and to form pure barium ferrite powder at 1073 K. Pure single magnetic domain BaFe12O19 particles of M(30 kOe)≈54 emu/g, Mr≈28 emu/g, and Hc≈3.7 kOe were produced using [citric acid]/[metallic ions]=1.5 and pH7. 相似文献