Studies on Electronic Structure and Magnetic Properties of an Organic Magnet with Metallic Mn2+ and Cu2+ Ions

The electronic structure and the magnetic properties of the non-pure organic ferromagnetic compound MnCu(pbaOH)(H2O)3 with pbaOH = 2-hydroxy-1, 3-propylenebis (oxamato) are studied by using the density-functional theory with local-spin-density approximation. The density of states, total energy, and the spin magnetic moment are calculated. The calculations reveal that the compound MnCu(pbaOH)(H20)3 has a stable metal-ferromagnetic ground state, and the spin magnetic moment per molecule is 2.208 μB, and the spin magnetic moment is mainly from Mn ion and Cu ion. An antiferromagnetic order is expected and the antiferromagnetic exchange interaction of d-electrons of Cu and Mn passes through the antiferromagnetic interaction between the adjacent C, O, and N atoms along the path linking the atoms Cu and Mn.     

Ab-Initio Study of Electronic Structure and Magnetic Properties of Pipz-H2 [MnF4（HF2）]

The full-potential linearized augmented plane wave method was applied to study the electronic and the magnetic properties of the compound pipz-H2[MnF4(HF2)](pipz=piperazine). The band structure, the total density of states, the partial density of states and the electron density were calculated to explain the electronic and the magnetic properties of pipz-H2[MnF4(HF2)] in the ferromagnetic state. It is found that the magnetic moment of the molecule mainly comes from the Mn atoms with partial contribution from the F atoms. The symmetrical σ/σ bonds via H atoms along Mn-F-H-F-Mn chains and the weak direct-exchange interaction between F(2), F(3) and Mn atoms have effect on the electronic structure and the magnetism of pipz-H2 [MnF4(HF2)].     

Electronic structure and magnetic properties of substitutional transition-metal atoms in GaN nanotubes

The electronic structure and magnetic properties of the transition-metal(TM) atoms(Sc–Zn, Pt and Au) doped zigzag GaN single-walled nanotubes(NTs) are investigated using first-principles spin-polarized density functional calculations. Our results show that the bindings of all TM atoms are stable with the binding energy in the range of 6–16 eV. The Sc- and V-doped GaN NTs exhibit a nonmagnetic behavior. The GaN NTs doped with Ti, Mn, Ni, Cu and Pt are antiferromagnetic. On the contrary, the Cr-, Fe-, Co-, Zn- and Au-doped GaN NTs show the ferromagnetic characteristics. The Mn- and Codoped GaN NTs induce the largest local moment of 4μB among these TM atoms. The local magnetic moment is dominated by the contribution from the substitutional TM atom and the N atoms bonded with it.     

Magnetic and Electronic Properties of Double Perovskite Ba_2SmNbO_6 without Octahedral Tilting by First Principle Calculations

The structural, magnetic and electronic properties of the double perovskite Ba_2 SmNbO_6(for the simple cubic structure where no octahedral tilting exists anymore) are studied using the density functional theory within the generalized gradient approximation as well as taking into account the on-site Coulomb repulsive interaction.The total energy, the spin magnetic moment, the band structure and the density of states are calculated. The optimization of the lattice constants is 8.5173 A, which is in good agreement with the experimental value 8.5180 A.The calculations reveal that Ba_2 SmNbO_6 has a stable ferromagnetic ground state and the spin magnetic moment per molecule is 5.00μB/f.u. which comes mostly from the Sm~(3+) ion only. By analysis of the band structure,the compound exhibits the direct band gap material and half-metallic ferromagnetic nature with 100% spin-up polarization, which implies potential applications of this new lanthanide compound in magneto-electronic and spintronic devices.     

Magnetic interactions in a proposed diluted magnetic semiconductor(Ba_(1-x)K_x)(Zn_(1-y)Mn_y)_2P_2

By using first-principles electronic structure calculations, we have studied the magnetic interactions in a proposed BaZn_2P_2-based diluted magnetic semiconductor(DMS). For a typical compound Ba(Zn_(0.944)Mn_(0.056))_2P_2 with only spin doping, due to the superexchange interaction between Mn atoms and the lack of itinerant carriers, the short-range antiferromagnetic coupling dominates. Partially substituting K atoms for Ba atoms, which introduces itinerant hole carriers into the p orbitals of P atoms so as to link distant Mn moments with the spin-polarized hole carriers via the p–d hybridization between P and Mn atoms, is very crucial for the appearance of ferromagnetism in the compound. Furthermore, applying hydrostatic pressure first enhances and then decreases the ferromagnetic coupling in(Ba0.75 K0.25)(Zn_(0.944)Mn_(0.056))_2P_2 at a turning point around 15 GPa, which results from the combined effects of the pressure-induced variations of electron delocalization and p–d hybridization. Compared with the BaZn_2 As_2-based DMS, the substitution of P for As can modulate the magnetic coupling effectively. Both the results for BaZn_2 P_2-based and BaZn_2As_2-based DMSs demonstrate that the robust antiferromagnetic(AFM) coupling between the nearest Mn–Mn pairs bridged by anions is harmful to improving the performance of these Ⅱ–Ⅱ–Ⅴ based DMS materials.     

Magnetic Properties and magnetic phase diagrams of intermetallic compound GdMn2Ge2

A modified Yafet－Kittle model is applied to investigate the magnetic properties and magnetic phase transition of the intermetallic compound GdMn_2Ge_2. Theoretical analysis and calculation show that there are five possible magnetic structures in GdMn_2Ge_2. Variations of external magnetic field and temperature give rise to the first-order or second-order magnetic transitions from one phase to another. Based on this model, the magnetic curves of GdMn_2Ge_2 single crystals at different temperatures are calculated and a good agreement with experimental data has obtained. Based on the calculation, the H－T magnetic phase diagrams of GdMn_2Ge_2 are depicted. The Gd－Gd, Gd－Mn, intralayer Mn－Mn and interlayer Mn－Mn exchange coupling parameters are estimated. It is shown that, in order to describe the magnetic properties of GdMn_2Ge_2, the lattice constant and temperature dependence of interlayer Mn－Mn exchange interaction must be taken into account.     

First-principles calculations for titanium monoxide clusters TinO （n=1-9）

Based on the density-functional theory, this paper studies the geometric and magnetic properties of TinO （n=1-9） clusters. The resulting geometries show that the oxygen atom remains on the surface of clusters and does not change the geometry of Tin significantly. The binding energy, second-order energy differences with the size of clusters show that Ti7O cluster is endowed with special stability. The stability of TinO clusters is validated by the recent time-of-flight mass spectra. The total magnetic moments for TinO clusters with n=1-4, 8-9 are constant with 2 and drop to zero at n=5-7. The local magnetic moment and charge partition of each atom, and the density of states are discussed. The magnetic moment of the TinO is clearly dominated by the localized 3d electrons of Ti atoms while the oxygen atom contributes a very small amount of spin in TinO clusters.     

Magnetic Properties of Spin-Ladder Compound Sr14 （Cu1-yFey）24O41

Magnetic properties of spin-ladder compounds Sr14（Cu1-yFey）24O41 （0 ≤ y ≤ 0.05） are investigated in the temperature range from 10 to 300 K. The result reveals that all the samples exhibit magnetic crossover behavior in the paramagnetic range, and Fe^3＋ doping can efficiently increase the susceptibility due to the large moment of Fe^3＋. Both the observations are consistent with our previous investigation on transport behaviors, indicating the strong correlation between the magnetism and transport behaviors. The spin gap is evidenced in all the samples, and strengthens as Fe^3＋ doping level increases, which can be associated with the antiferromagnetic interaction between Fe^3＋ and Cu cations.     

First-Principles Study of Electronic Structure of the Laves Phase ZrFe2

We perform the ab initio calculation for obtaining the density of states and magnetic properties of ZrFe2 Laves phase compound based on the method of augmented plane waves plus local orbital The results indicate that the ferromagnetic state is more stable than the paramagnetic one, but with a slightly larger volume. The 3d - 4d exchange interactions between Fe and Zr electrons lead to the antiparallel coupling for Fe 3d and Zr 4d states, which is responsible for the ferrimagnetic ordering of the compound. The resulting magnetic moment of about 1.98μB for Fe is spatially localized near the Fe site, while around Zr a small but extended negative spin states causes a moment of about -0.44 μB. Moreover, the resulting magnetic moments with the generalized gradient approximation are more consistent with experimental values than that of the local-spin density approximation.     

Effects of oxygen vacancy location on the electronic structure and spin density of Co-doped rutile TiO₂ dilute magnetic semiconductors

According to density functional theory (DFT) using the plane wave base and pseudo-potential, we investigate the effects of the specific location of oxygen vacancy (VO) in a (Ti,Co)O 6 distorted octahedron on the spin density and magnetic properties of Co-doped rutile TiO2 dilute magnetic semiconductors. Our calculations suggest that the V O location has a significant influence on the magnetic moment of individual Co cations. In the case where two Co atoms are separated far away from each other, when the V O is located at the equatorial site of a Co-contained octahedron, the ground state of the two Co cations is d6 (t3 2g ↑, t 3 2g ↓) without any magnetic moment. However, if the V O is located at the apical site, these two Co sites have different ground states and magnetic moments. The spin densities are also observed to be modified by the exchange coupling between the Co cations and the location of V O . Some positive spin polarization is induced around the adjacent O ions.     

Ab initio study of electronic structure and magnetic properties of copper (II) terephthalate

The first principles within the full potential linearized augmented plane wave (FP-LAPW) method was applied to study the compound of Cutp(OH₂)₂. The density of states, the electronic band structure and the spin magnetic moment are calculated. The calculations reveal that the compound has a ferromagnetic interaction arising from the bridging water molecule. The spin magnetic moment 1.0μ_B per molecule mainly comes from the Cu ion with little contribution from O, C anion.     

ab initio Study of Electronic Structure and Magnetic Properties of a Novel Two-Dimensional Copper(II)-Radical Complex [Cu(NTTmPy)2(N3)2]n

The full-potential linearized augmented plane wave (FPLAPW) method with the generalized gradient approximations (GGA) is applied to study the compound [Cu(NTTmPy)₂(N₃)₂]_n (NITmPy=2-(3'-Pyridy1)-4, 4, 5, 5-tetramethylimidazolin-1-oxy1-3-oxide). The total density of states (DOS) and the partial density of states (pDOS) are calculated to explain the electronic and the magnetic properties of [Cu(NTTmPy)₂(N₃)₂]_n. It is found that [Cu(NTTmPy)₂(N₃)₂]_n is stable in the ferromagnetic state and the magnetic moment of the molecule mainly comes from the Cu atoms (0.518 μ_B) with partial contribution from N, O atoms of nitronyl nitroxide radicals. There exist orbital hybridization between 3d orbital of Cu and p orbitals of N(1) (from pyridyl rings of the NITmPy ligands) and N(4) (from azido group) and the weak direct exchange interactions between Cu and O atoms of nitronyl nitroxides. In addition, the bridging carbon atom (C(6)) carries a significant negative spin density (-0.019μ_B). The sign alternation of the magnetic moment along the pyridyl ring is obtained, which agrees with experiments.     

Magnetic properties of the intermetallic compounds Gd(Mn1−xNix)2

The magnetic properties of pseudobinary compounds Gd(Mn_1−xNi_x)₂ were studied to understand the type of magnetic interaction among the constituent atoms of the parent binary compound. The Arrott plot for GdMn₂ indicates no spontaneous magnetization. The magnetization and the Curie temperature increase with increasing concentration of Ni on the Mn rich side. The collapse of the Mn moment makes the Gd moment dominant in magnetization with increasing Ni concentration.     

Ab initio Study of Electronic Structure and Magnetic Properties of Two Novel Neptunium （V） Sulfates： iaK3（ipO2）4（SO4）4（H2O）2 and iaipO2SO4H2O

Ab initio within the full potential linearized augmented plane wave （FP-LAPW） method with the GGA＋U approach is applied to study the electronic structures of two compounds NaK3（NpO2）4（SO4）4（H2O）2 and NaNpO2SO4H2O. The present calculations show that the major part of the spin magnetic moment in these two compounds is from Np（V） ions, and the origin of the cation-cation interactions between Np comes from the spin polarization effect within Np-ONv-Np bonds.     

2,4,6-三吡啶基三嗪-芳香羧酸镝配合物的合成及其荧光性能

分别以2,4,6-三吡啶基三嗪( TPTZ)、对羟基苯甲酸和对苯二甲酸为配体,以Dy3+为中心合成了不同组成的5种配合物.对其进行了元素分析、紫外光谱、红外光谱、荧光激发和发射光谱的测定.推测配合物的组成分别为:(1)Dy(TPTZ)(NO3)3(C2H5OH)·H2O; (2) Dy (TPTZ)2 (NO3)3 (...     

Electronic Structure and Magnetic Properties of Cu[C(CN)3]2 and Mn[C(CN)3]2 Based on First Principles

The electronic structure and the magnetic properties of the molecule-based ferromagnets Cu[C(CN)₃]₂ and Mn[C(CN)₃]₂ are studied accordingto first principles within density-functional theory (DFT) and the full potential linearized augmented plane wave (FP-LAPW) method. The total energy, atomic spin magnetic moments, and density of states (DOS) of Cu[C(CN)₃]₂ and Mn[C(CN)₃]₂ are all calculated. The calculations reveal that the compounds have a stable ferromagnetic ground state and half-metallic properties. The total spin magnetic moment is 1.0 μ_B for Cu[C(CN)₃]₂ and 5.0 μ_B for Mn[C(CN)₃]₂ per molecule, the magnetic moment mainly comes from metal atoms, although there is a slight contribution from N and C atoms.     

Neutron diffraction study of magnetic ordering in ErMn2Si2, ErMn2Ge2 and ErFe2Si2

Neutron diffraction study of polycrystalline compounds ErMn₂Si₂, ErMn₂Ge₂ and ErFe₂Si₂ was performed in the temperature range between 1.8 and 293 K. All compounds have tetragonal, ThCr₂Si₂-type crystal structure. The antiferromagnetic collinear structure of ErMn₂Si₂ and ErMn₂Ge₂ at both RT and LNT, consists of a sequence + - + - of ferromagnetic layers of Mn atoms. The magnetic moment of an Mn atom (≈2μ_B) is parallel to the c-axist. At low temperatures (LHT and lower), the ferromagnetic ordering within the Er sublattice is observed. The magnetic moment (μ_Er ≈ 9μ_B) is perpendicular to the c-axis. From the temperature dependence of the intensities of the magnetic peaks, the following values for the Curie temperatures were obtained: (10±5) K for ErMn₂Si₂ and (8.5±3) K for ErMn₂Ge₂. For ErFe₂Si₂ a collinear antiferromagnetic structure of the + - - + type was found, the magnetic unit cell consisting of the chemical one, doubled along the c-axis.     

Mn掺杂(ZnSe)12团簇物性研究

采用密度泛函理论研究Mn原子单掺杂和双掺杂（ZnSe）₁₂团簇的结构、电子性质和磁性质.考虑三种掺杂方式：替代掺杂,外掺杂和内掺杂.比较掺杂团簇的稳定性.结果表明：无论是单掺杂还是双掺杂,替代掺杂团簇是最稳定结构.在结构优化的基础上对掺杂团簇进行磁性计算.团簇磁矩主要来自Mn原子3d态的贡献,4s和4p态贡献了一小部分磁矩.由于轨道杂化,相邻的Zn和Se原子上产生少量自旋.研究发现：内双掺杂团簇是铁磁耦合,在纳米量子器件领域有潜在的应用价值.     

The first-principle study on the electronic structure and magnetic properties of polymer Cu(HCO 2 )(NO 3 )(pyz) {pyz = Pyrazine}

The first principle method was applied to study the electronic structure and magnetic properties of the compound of Cu(HCO₂)(NO₃)(pyz). The density of states, the electronic structure and the spin magnetic moments are calculated. The results reveal that the compound has a ferromagnetic interaction arising from the bridging μ- HCO₂⁻ and pyz ligands, and the ferromagnetic properties come from the spin delocalization effect. The spin magnetic moment per molecule mainly comes from the Cu ion, but has little contribution from O, N and C anion.     

Pr2(Fe0.8Co0.2)14B磁结构的中子衍射研究

本文报道用中子衍射测定的含硼稀土过渡族金属间化合物Pr₂(Fe_0.8Co_0.2)₁₄B的晶体结构与磁结构。将中子三轴谱仪用作二轴粉末衍射仪,在室温测该化合物粉末样品的中子衍射强度,用轮廓精化法弥合衍射数据。该化合物属Nd₂Fe₁₄B类四方结构,α=8.8110?,c=12.2307?。设Pr,Fe和Co原子磁矩间为铁磁耦合,同一晶位的Fe,Co原子磁矩相等,存在沿c轴的易磁化 关键词：