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831.
Mustafa Burak Coban Cagdas Kocak Muhittin Aygun Asma Amjad 《Molecular Crystals and Liquid Crystals》2017,648(1):202-215
Two coordination polymers, {[Ln(2-stp)(4,4′-bipy)(H2O)].(H2O)}, [Ln = Dy (1) and Eu (2), 2-stp = 2-sulfoterephthalate and 4,4′-bipy = 4,4′-bipyridine] have been characterized by solid state UV-vis, FTIR spectra, X-ray single crystal diffraction and solid state photoluminescence. Variable-temperature magnetic susceptibility and isothermal magnetization as function of external magnetic field is also studied for both complexes. After ligand-mediated excitation, both complexes show the characteristic visible and NIR luminescence of the corresponding LnIII ions (Ln = Dy, Eu) which is due to efficient energy transfer from the ligands to the central LnIII ions via an antenna effect. The indirect energy transfer in both complexes has been investigated and discussed in detail. 相似文献
832.
A room temperature and microwave method for the preparation M-Doped ZnO, where M=Co, Cr, Fe, Mn & Ni, is described. X-ray
diffraction of the synthesized samples shows a single phase ZnO structure without any indication of the dopant. Magnetic studies
of the as prepared samples show it to be paramagnetic. However, hydrogenation of particular samples at 573 K for 6 h resulted
in transforming the samples to a room temperature ferromagnet. 相似文献
833.
用全势线性缀加平面波方法,考虑局域自旋密度近似研究虚晶掺杂MgCNi3的超导电性和磁性.计算了自旋极化能带结构、体弹性模量和它对压力的导数、原子磁矩m及其变化率.计算结果表明,对于电子掺杂的Mg1-xAlxCNi3(0≤x≤0.5),超导电性和磁涨落随掺杂量的增加逐渐减小.空穴掺杂的Mg1-xNaxCNi3,在x=0.12处出现铁磁相变,超导电性消失.在MgCNi3少量空穴掺杂区域(0≤x<0.12),表现为超导与磁涨落共存的不稳定状态.
关键词:
超导电性
能带结构
态密度
磁性 相似文献
834.
835.
Preparation, Structures, and Properties of SmBeF4 and SrBeF4 – Unusual Variants of the Baryt Type Structure SmBeF4 has been obtained as orange-yellow crystals and SrBeF4 as colourless crystals while heating mixtures of SmF3, Sm-powder, BeF2 (2 : 1 : 3) and SrF2 and BeF2 (1 : 1), respectively, under Ar after 7–10 d at about 700°C. SmBeF4 crystallizes in Pna21 (No. 33) with a = 846.1(5), b = 676.9(5), c = 524.1(4) pm and SrBeF4 in P21/n (Nr. 14) with a = 529.5(5), b = 830.9(2), c = 678.8(4) pm and β = 90.0°. The structures of SmBeF4 and the room temperature modification of SrBeF4 are related to the baryt type structure. The differences to the structure BaSO4 are mutual rotations of the BeF4 tetrahedra and their shift with respect to the Sm and Sr framework, respectively. According to the refinement of the structure of SmBeF4 at ?174°C these effects are enhanced at low temperatures. SmBeF4 exhibits sharp luminescence lines at around 690nm. Measurements of the magnetic susceptibility show the temperature dependence typically found for Sm2+. The Madelung parts of the lattice energy for SmBeF4 und SrBeF4 have been calculated and discussed. 相似文献
836.
We study theoretically the Co magnetization suppression at the Co–M (M=Ti, Nb, Mo, Re, Os, Ir and Pt) interface. We consider (1) M(1×1) overlayer on the FCC(1 1 1) or HCP(0 0 0 1) slab, (2) c(2×2) Co–M alloy above the same surfaces. In the latter case, the Co magnetization is reduced to about 0.5 μB by Ti, Nb, Mo and Re, but the effect is probably an overestimation because of compression of M–Co bonds. At Co atoms below the M(1×1) overlayer, the Co magnetization does not drop below 1 μB. We discuss also the Co–M antiferromagnetic coupling. 相似文献
837.
Takehiko Mori 《Journal of solid state chemistry》2002,168(2):433-437
Inter-dimer magnetic interactions J in BEDT-TTF (bis(ethylenedithio)tetrathiafulvalene) salts in the Mott insulator regime are estimated from the intermolecular overlap integrals. The estimated J values are compared with the experimental results, and the stable spin alignment and the dimensionality of the spin systems are discussed. 相似文献
838.
A microscopic theory of interplay of superconductivity and antiferromagnetism in rare earth ternary systems is developed from
first principles for less than half filledf atomic shells. Self consistent equations for the superconducting order parameter Δ and magnetic order parameter Γ, are derived
using a Green’s function technique and equation of motion method. The theory is applied to explain the experimental results
in the antiferromagnetic superconductor SmRh4B4. The present model explains true coexistence of superconductivity and antiferromagnetism and the suppression of superconductivity
by antiferromagnetism. The behaviour of superconducting order parameter (Δ), magnetic order parameter (Γ), the specific heat,
the density of states, free energy and critical field (H
c) is also studied for the system SmRh4B4. 相似文献
839.
强制体积磁致伸缩的数量级极小(10-10~10-9[(103/4π)(A/m)]-1),如通过测量三个互成直角方向的线磁致伸缩(10-6[(103/4π)(A/m)]-1)再正负迭加则很难测准。本文利用热力学关系:(dω/dH)T,p=-(dMs/dp)T,H,用静水压法在0.000 1~2.4 GPa范围测得七种非晶合金Fe81.6Si4.6B13.8、Fe46.3Co0.03Ni46.5Si3.75V0.92B2.5、Fe75Cr5Si5B15、Fe73.9Co8.3Si4.4B13.4、Fe75Ni5Si5B15、Fe78.75Cu1.25Si5B15和(Fe0.85Co0.15)82Cu0.4Si4.4B13.2的强制体积磁致伸缩及其随静水压p的变化。结果表明:(1)其中六种属于第一类压磁效应。(dω/dH)T,p在大部分压力下为正,p增加时Ms不断减小;(dω/dH)T,p仅在几个狭窄的压力范围为负。可归因于磁性原子与非磁性原子的化学短程序在压力下的变化。(2)非晶合金Fe78.75Cu1.25Si5B15属于第二类压磁效应。(dω/dH)T,p在绝大部分压力下为负。Ms反常升高与Cu的特殊作用有关。 相似文献
840.
Kikuo Harigaya Atsushi Yamashiro Yukihiro Shimoi Katsunori Wakabayashi 《Current Applied Physics》2004,4(6):587-590
We theoretically study the electronic states in graphene ribbons which are strongly affected by the edge states, the peculiar non-bonding molecular orbitals localized along the zigzag edges of the ribbons. New kinds of edge localized electronic states with spin and charge polarizations are found in the mean field solutions of the extended Hubbard model with onsite and nearest-neighbor Coulomb repulsions. These novel states appear due to the interplay between the edge states and the Fermi instabilities. We also examine the competition between the charge polarized state and the spin polarized state to draw a phase diagram depending on Coulomb parameters. The results obtained by the mean field calculations with the extended Hubbard model modified to include Coulomb integrals provide useful insights to understand and functionalize the nanoscale materials. 相似文献