Electronic and Magnetic Properties of Os-Doped Rhodium Clusters: a Theoretical Study

The stability and electronic and magnetic properties of Rh_nOs (n=?2–12) clusters in their most stable configurations were systematically studied by using density functional theory (DFT) at M06L/aug-cc-pVDZ level. Calculation of the second-order difference of energies and fragmentation energies exhibited that Rh₃Os, Rh₅Os, Rh₇Os, and Rh₉Os clusters are more stable than any other clusters. The calculated HOMO-LUMO energy gaps of the Rh_nOs clusters are found to be in the range of 0.018 to 0.299 eV, implying that the metallic behavior can appear in these clusters. Accordingly, the Rh_nOs clusters can be employed as heterogeneous nanocatalysts in many chemical reactions. The local Fukui function (\(f_{k}^{-} )\) has also been calculated, and the obtained results reveal that the highest \(f_{k}^{-} \) values are predicted for the Rh atoms. Therefore, the Rh atoms in the clusters are considered the most reactive sites that undergo reactions with electrophilic reagents. The analysis of the magnetic properties of the Rh_nOs clusters shows that the total magnetic moment per atom of these clusters varies from 0.67 to 1.75 µ_B/atom. And, the PDOS analysis reveals that the d orbitals play a crucial role for the magnetism of the Rh_nOs clusters, and the contribution of the s and p orbitals is small.     

First Principles Study of Electronic,Magnetic, and Optical Properties of TbN and ErN Nanolayers

The electronic, magnetic, and optical properties of TbN and ErN nanolayers in the presence of spin orbit coupling using density functional theory using the WIEN2k package are investigated. The stable phase of TbN and ErN bulk using generalized gradient approximation (GGA) approach is studied. The total and partial electron density of states of ErN and TbN nanolayers with two different thicknesses in ferromagnetic phase within GGA and Engel–Vosko GGA (GGA_EV) approaches is calculated. The total and local magnetic moments of these nanolayers are studied. The calculated magnetic moment at Er atomic position of ErN nanolayer is larger than the corresponding value at Tb atomic position of TbN nanolayer. Furthermore, the real and imaginary parts of the dielectric function and the reflectivity and absorption spectra of these nanolayers within GGA_EV approach are studied.     

Magnetic Behaviors of 3d Transition Metal-Doped Silicane: a First-Principle Study

We perform a first-principle computation on the magnetic properties of 3d transition metal (TM)-doped silicane. All the substituted systems are energetically stable. Robust half-metallic properties are found in Ti-, V- and Mn-substituted silicane. At the dopant concentration of 12.5%, we evaluate that the Curie temperature of Ti- and Mn-substituted silicane is at 340 and 666 K respectively in the mean-field approximation. Consequently, room-temperature ferromagnetism is easily achievable in Ti- and Mn-substituted silicane. Our work demonstrates potential application of Ti and Mn-substituted silicane for room-temperature spintronic devices.     

Electronic and Magnetic Theoretical Investigation of Antiferromagnetically ErRh Layers

Self-consistent ab initio calculations, based on the DFT (Density Functional Theory) approach and using the FLAPW (Full potential Linear Augmented Plane Wave) method, are performed to investigate both electronic and magnetic properties of the ErRh layers. Polarized spin and spin–orbit coupling are included in calculations within the framework of the antiferromagnetic state between two sites of Er atoms. Magnetic moments considered to lie along axes are computed. The data obtained from the ab-initio calculations are then used as input for the high-temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The exchange integrals between the magnetic atoms in the same sites are given by using mean field theory. The HTSEs of the magnetic susceptibility of ErRh antiferromagnetic spin-S through two model: Heisenberg and XY for ErRh layers, are studied to sixth order series in β=1/k _B T. The critical exponent γ associated with the magnetic susceptibility is deduced for the two models.     

Theoretical Study of Electronic and Magnetic Properties of Newly Derived Iron–Pnictide Compound

A theoretical study based on DFT-LDA of the structural, electronic, and magnetic properties of the new substitution CaFe₂B₂ compound derived from BaFe₂As₂ is presented. Through a relaxation calculation, we found that this compound crystallizes in tetragonal and orthorhombic phases. Formation energies, lattice parameters, density of states, and magnetic moments are calculated. The ground state for this compound is nonmagnetic (NM). As for the anti-ferromagnetic state, more formation energy is characterized by large magnetic moment on each Fe atoms for AFM spin configuration. The results are compared with previous calculations and experimental data. The results of electronic and magnetic properties show that the partial and total density of states for NM, FM, and AFM phases are characterized by strong hybridization between Fe and B atoms. The energy band structure indicates the presence of overlapping valence and conduction bands at the Fermi level. The analyses of charge densities show that the type of bonding in the CaFe₂B₂ compound is metallic. An important resemblance with the original compound is observed which leads us to think that this compound is maybe a superconducting material.     

First-Principles Study on the Structural, Electronic, Magnetic and?Optical Properties of UFe2 and PuFe2 Compounds

The structural, electronic and magnetic properties of UFe₂ and PuFe₂ have been calculated in the presence and absence of spin?Corbit interaction using density-functional theory by the WIEN2K package. The total energy calculations indicate that at zero pressure the ferromagnetic phase is the most stable phase. Both the energy band calculation and the density of states curves indicate that spin?Corbit interaction has a considerable effect and cannot be ignored. The magnetic moment calculation within local density approximation (LDA) and generalized gradient approximation (GGA) approaches show that LDA and GGA are not good approaches for this compound. To improve the result, we have calculated the magnetic moment using the GGA+U and LDA+U approaches. The calculation of the magnetic moment as a function of pressure has been investigated.     

Cl浓度对ZnS:Cl电子结构和光学性质的影响

采用第一性原理的平面波赝势方法和广义梯度近似,研究了不同浓度Cl掺杂ZnS的电子结构和光学性质.结果表明,掺杂后带隙随杂质浓度的增大而减小,价带变窄,杂质能级展宽;Cl浓度的增大使ZnS:Cl在可见光区的吸收范围增大,吸收增强,光学吸收边出现红移,且在蓝光区形成一个新的吸收峰,与实验结果吻合,新吸收峰随着掺杂浓度的增大出现红移.     

Theoretical Investigation of Structural,Electronic, and Magnetic Properties of V-Doped MgSe and MgTe Semiconductors

In this study, we have explored the structural, electronic, and magnetic properties of V-doped zincblende MgSe and MgTe compounds using density functional calculations. The Wu-Cohen generalized gradient approximation is used for optimizing the structural properties, while the modified Becke and Johnson local (spin) density approximation functional has been employed to compute the electronic and magnetic properties. The spin dependent band structures, electronic density of state, and magnetic moments calculated for V-doped MgSe and MgTe semiconductors exhibit occurrence of 100 % spin polarization at the Fermi level which confirms stable half-metallic ferromagnetism in these materials. The spin-down gaps and the half-metallic gaps are analyzed in terms of V-3d and Se-4p (Te-5 p) hybridization, where it is observed that the V-3dstates play a key role in generating spin polarization and the magnetic moment in these compounds. The exchange constants N ₀ αand N ₀ β have been calculated to demonstrate the effects resulting from exchange splitting process. Furthermore, spin-polarized charge density calculation is presented for elucidating the bonding nature, while pressure dependence of total magnetic moment for three concentrations of V-doped MgSe and MgTe are also discussed.     

压力下纤锌矿ZnS电子结构的第一性原理研究

计算了纤锌矿ZnS以及压力体系下的电子结构,分析和比较了体系的能带结构、态密度、费米能级以及应力对ZnS体系电子结构的影响.所有计算都是基于密度泛函理论(DFT)框架下的第一原理平面波超软赝势方法.结果表明:随着压力的逐渐增大,Zn-S键长缩短,相互作用增强,价带与导带分别向低能和高能方向移动,带隙Eg展宽,这从理论上解释了ZnS带边和能隙与压力的关系.     

Spontaneous Polarization and Magnetic Investigation Of BiXO3 (X=Co,Mn, Fe,V, Zn): First-Principle Study

Spontaneous polarization and magnetic properties of BiXO3 with X = Co, Fe, Mn, V, and Zn have been studied using the full-potential, linear augmented plane wave (FP-LAPW) method with GGA and mBJ implemented in the WIEN2K code. The investigation shows that BiXO3 with X = Co, Fe, Mn, and Zn is stable in the antiferromagnetic state while for BiVO3, the magnetic stability was shown in the ferromagnetic state. The calculation shows the existence of a charge transfer between p states of oxygen and d states of Co and Fe for X = Co and Fe. The existence of Co, Fe, Mn, and V makes BiXO3 a non-absorbent compound. However, for Zn, the structure behaves as an absorbent compound especially in the visible light. We note that the spontaneous polarization is calculated with Berry phase BI and was found very close and comparable with other works.     

补偿型共掺杂ZnS电子特性的第一性原理计算

基于密度泛函理论的第一性原理平面波赝势方法,对ZnS(Cu,Cl、Br、I)共掺杂体系的晶格结构和电子性质进行了研究。结果表明,相对于单掺杂ZnS体系,补偿型的共掺ZnS体系形成能更低,更有利于提高可见光的催化效率,且由于p-d电子排斥效应使价带向高能方向展宽,而Cu的3p态与非金属原子的杂质态使导带底下移,从而使共掺杂ZnS体系的能带带隙变窄,尤其是CuZnBrS-ZnS带隙值减少了30%,从而延伸吸收边界到可见光区域。且CuZnBrS-ZnS中m*e/m*h相对较大,降低了电子-空穴对重组率,提高了量子效率。最后对补偿型共掺ZnS电子结构进行了讨论。     

Tuning of the Optical,Electronic, and Magnetic Properties of Boron Nitride Nanosheets with Oxygen Doping and Functionalization

Engineering of the optical, electronic, and magnetic properties of hexagonal boron nitride (h‐BN) nanomaterials via oxygen doping and functionalization has been envisaged in theory. However, it is still unclear as to what extent these properties can be altered using such methodology because of the lack of significant experimental progress and systematic theoretical investigations. Therefore, here, comprehensive theoretical predictions verified by solid experimental confirmations are provided, which unambiguously answer this long‐standing question. Narrowing of the optical bandgap in h‐BN nanosheets (from ≈5.5 eV down to 2.1 eV) and the appearance of paramagnetism and photoluminescence (of both Stokes and anti‐Stokes types) in them after oxygen doping and functionalization are discussed. These results are highly valuable for further advances in semiconducting nanoscale electronics, optoelectronics, and spintronics.     

铁掺杂羟基磷灰石的制备及在强磁场中的定向研究

生物陶瓷表面纳米结构能够影响成骨细胞增殖和分化, 其表面微观结构的控制, 特别是烧结前晶粒取向调控, 是设计开发生物活性陶瓷的关键之一。针对羟基磷灰石晶粒取向调控问题, 重点研究了铁掺杂羟基磷灰石晶体在强磁场中的取向。分别采用共沉淀法和共沉淀-水热法合成了羟基磷灰石(HA)和铁-羟基磷灰石(Fe-HA), 通过XRD、SEM、TEM、PPMS和ICP等对HA和Fe-HA的物相、微观形貌、磁学性能、元素组成进行了表征和分析。研究发现：Fe-HA物相与HA相同, 没有明显的杂质相; HA为抗磁性, Fe-HA转化为顺磁性; 共沉淀法粉体为针状, 共沉淀-水热法粉体为短棒状, 针状粉体在强磁场中不能定向, 短棒状粉体能够定向; 在单一方向强磁场中, HA不能单轴定向, Fe-HA能够在一定程度上沿c轴取向。     

Study of the Structural,Electronic, Magnetic,and Optical Properties of Mn<Subscript>2</Subscript>ZrGa Full-Heusler Alloy: First-Principles Calculations

In this work, the structural, electronic, magnetic, and optical properties of Mn₂ZrGa full-Heusler alloy were investigated by using density functional theory (DFT) calculations. It is found that the spin-up states have a metallic character, but the spin-down bands have a pseudo-gap at the Fermi level. The total spin magnetic moment of Mn₂ZrGa (per formula unit) is 3.00 µ _B at an equilibrium lattice parameter of 6.15 Å. The calculations show that Mn₂ZrGa is a ferrimagnetic with 81% spin polarization at equilibrium lattice parameter. The effect of lattice parameter distortion on the magnetic properties and spin polarization is also studied. It is found that the total magnetic moment preserves its value for a lattice parameter range of 5.96–6.30 Å. The decreasing of the lattice parameter leads to improvement of spin polarization. The real and imaginary parts of dielectric function and hence the optical properties including energy absorption spectrum, reflectivity, and optical conductivity are also calculated. The value of plasma frequency for spin-up and down electrons is located at 1.78 and 0.74 eV, respectively.     

First-Principle Calculations of Structural,Electronic, and Magnetic Properties of Cubic Al1−x TM x N (TM = V,Cr, Mn,Fe)

We investigate the structural, electronic, and magnetic properties of zinc-blende diluted magnetic semiconductors (DMS) Al _1?x TM _x N for transition metals (TM) = V, Cr, Mn, and Fe at x = 0.125 and 0.25, using first-principle calculations with the full-potential linearized augmented plane wave (FP-LAPW) method within the density functional theory and local spin-density approximation, in an aim to predict properties of Al _1?x TM _x N compounds. We have analysed the reliance of structural parameter values on the composition x in the range of x= 0.125?0.25. Results of calculated electronic structures reveal that Al _1?x TM _x N have stable ferromagnetic ground state and they are ideal half-metallic (HM) ferromagnetic at their equilibrium lattice constants. We have also studied the magnetic moment of Al _1?x TM _x N by increasing the concentration of TM atom; this is the most important source of the total magnetic moment in these alloys, while the contributions from Al, N, and interstitial moments are minor.     

First-Principle Study of Electronic and Half-Metallic Ferromagnetic Properties of Vanadium (V)-Doped Cubic BP and InP

In this study, we use the first-principle calculations of density functional theory with gradient generalized approximation of Wu–Cohen to investigate the doping effect of vanadium impurity on structural, electronic and magnetic properties of In_1?x V _x P and B_1?x V _x P alloys at various concentrations x = 0.0625, 0.125 and 0.25. Owing to the metallic nature of majority spin and semiconducting minority spin, the In_1?x V _x P compounds exhibit a half-metallic character with total magnetic moments of 2 μ _B, while the B_1?x V _x P has metallic nature for all concentrations. The results of exchange parameters revealed that exchange coupling between vanadium atoms and the conduction band is ferromagnetic, confirming the magnetic feature of In_1?x V _x P and B_1?x V _x P. From our findings, we have predicted that the In_1?x V _x P alloys seem to be potential materials for spintronics.