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Half-metallic, Magnetic, and Optical Properties for the (001) Surface of Binary Heusler Alloy MgCl3
摘要： The half-metallic (HM), magnetic, and optical properties for the (001) surface of binary Heusler alloy MgCl3 were investigated by the first-principles method. The Mg*Mg*-term and Mg*Mg-term had the lower surface energies among the ClCl-term, Mg*Mg*-term, ClMg-term, ClCl*-term, and Mg*Mg-term (001) surfaces, thus, they were the more stable surfaces. The band decomposed charge density showed clearly the valence band maximum was contributed not only by the ClB-3p states but also the ClA-3p and ClC-3p states. The HM character was destroyed in all the five terminations of the (001) surface. The stable Mg*Mg*-term (001) surface had the largest spin polarization (≈ 83.0%). The hydrogen-termination effect showed an effective method to enlarge the spin polarizations for the ClCl-term and ClCl*-term surfaces to produce thin films which had potential applications in spintronics. There were great changes of atomic magnetic moments for Cl atoms in any layer. In energy range of 1.6–3.1 eV for the visible light, the Mg*Mg*-term had superiority in the absorption for purple light.
关键词： binary Heusler alloy,Half-metallic property,magnetic property,optical property
更新于2025-09-23 15:22:29
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The electronic and elasticity properties of new half-metallic chalcogenides Cu <sub/>3</sub> TMCh <sub/>4</sub> (TM?=?Cr, Fe and Ch?=?S, Se, Te): an <i>ab initio</i> study
摘要： The ternary copper-based chalcogenides Cu3TMCh4 (TM = Cr, Fe and Ch = S, Se, Te), which have simple cubic (SC) crystal structure and conform to P(cid:1)43m space group with 215 space number, have been investigated by spin-polarised generalised gradient approximation (GGA) in the framework of density functional theory (DFT). All systems have been considered in ferromagnetic (FM) order. The mechanical and thermal properties and the electronic band structures of these systems have been investigated after the well-optimised structural parameters have been obtained. The spin-polarised electronic band structures of all the systems exhibit half-metallic behaviour with band gaps in minority spin channel from 0.29 eV for Cu3FeTe4 to 1.08 eV for Cu3CrS4, while metallic band structures are observed for majority spins. This agrees with the calculated total magnetic moments which are close to integer values. The calculated negative formation enthalpies indicate the energetic and thermodynamic stability of these compounds. Moreover, the calculated elastic constants verify that these materials are stable mechanically due to satisfying Born stability criteria. The estimated anisotropy shear factors show that Cu3FeS4, Cu3FeSe4 and Cu3CrSe4 systems have nearly isotropic character with 1.004, 0.910, and 0.958 values, respectively, whereas other compounds have relatively low anisotropic behaviour.
关键词： electronic structure of bulk materials,density functional theory,chalcogenides,Half-metallic,mechanical properties of solids
更新于2025-09-23 15:21:21
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Prediction of a Dynamically Stable New Half-Metallic Phase for the BaN and BaC Compounds
摘要： The structural, magnetic, elastic, mechanical, and thermodynamic properties of BaC and BaN compounds in different phases were studied using first-principle calculations based on spin-polarized density functional theory within the generalized gradient approximation (GGA-PBEsol) and the modified Becke–Johnson approach (mBJ-GGA-PBEsol) for the exchange-correlation energy and potential. The following phases—rock-salt (NaCl), CsCl, zinc blende (ZB), NiAs- and WZ-type hexagonal, tetragonal (P4/nmm), and orthorombic (Pnma) phases of BaC and BaN compounds—were considered. We obtained that Pnma phase has the lowest energy configuration as a function of the volume for both the BaN and BaC compounds. The ferromagnetic phase is energetically favored with respect to the non-magnetic phase in the BaN and BaC compounds, except for the CsCl phase in the BaC compound. Considering the phonon dynamics of BaN and BaC compounds in the Pnma, NaCl, ZB, and WZ phases, we observed that the BaN and BaC compounds in the Pnma, NaCl, and ZB phases are dynamically stable. The calculated elastic properties for the Pnma, NaCl, and ZB phases show that they are elastically stable. The Pnma phase for the BaN and BaC compounds, which is a new phase was found to be dynamically and elastically stable. The BaN and BaC compounds exhibit half-metallic behavior in the Pnma, NaCl, and ZB phases. The half-metallic and magnetic character found in the BaN and BaC compounds are attributed to the presence of spin-polarized 2p orbitals of the nitrogen and carbon atoms, respectively. We found that BaN and BaC compounds are half-metallic ferromagnets with magnetic moment of 1 μB and 2 μB per formula unit, respectively. Using the GGA-PBEsol (mBJ-GGA-PBEsol) approach, our calculated half-metallic gaps for BaN and BaC compounds are 0.22 eV (0.54 eV) and 0.32 eV (0.44 eV) in the Pnma phase, 0.23 eV (1.32 eV) and 0.35 eV (1.00 eV) in the NaCl phase, and 0.38 eV (1.54 eV) and 0.50 eV (1.57 eV) in the ZB phase, respectively.
关键词： BaN,Density functional theory,Half-metallic,BaC,Phase stability,Phonon dynamics
更新于2025-09-23 15:21:01
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Electrically tunable spin diode effect in a tunneling junction of quantum dot
摘要： Control over the tunneling current in spintronic devices by electrical methods is an interesting topic, which is experiencing a burst of activity. In this paper, we theoretically investigate the transport property of electrons in a spin-diode structure consisting of a single quantum dot (QD) weakly coupled to one nonmagnetic (NM) and one half-metallic ferromagnet (HFM) leads, in which the QD has an artificial atomic nature. By modulating the gate voltage applied on the dot, we observe a pronounced decrease in the current for one bias direction. We show that this rectification is spin-dependent, which stems from the interplay between the spin accumulation and the Coulomb blockade on the quantum dot. The degree of such spin diode behavior is fully and precisely tunable using the gate and bias voltages. The present device can be realized within current technologies and has potential application in molecular spintronics and quantum information processing.
关键词： half-metallic ferromagnet,quantum dots,spin blockade,spin dependent electron tunneling
更新于2025-09-12 10:27:22
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revealed by resonant photoelectron spectroscopy
摘要： Resonant photoelectron spectroscopy at the Co and Mn 2p core absorption edges of half-metallic Co2MnGe has been performed to determine the element-speci?c density of states (DOS). A signi?cant contribution of the Mn 3d partial DOS near the Fermi level (EF) was clari?ed by measurement at the Mn 2p absorption edge. Further analysis by ?rst-principles calculation revealed that it has t2g symmetry, which must be responsible for the electrical conductivity along the line perpendicular to the ?lm plane. The dominant normal Auger contribution observed at the Co 2p absorption edge indicates delocalization of photoexcited Co 3d electrons. The difference in the degrees of localization of the Mn 3d and Co 3d electrons in Co2MnGe is explained by the ?rst-principles calculation. Our ?ndings of the element-/orbital-speci?c electronic states near EF will pave the way for future interface design of magnetic tunneling junctions to overcome the temperature-induced reduction of the magnetoresistance.
关键词： first-principles calculation,magnetic tunneling junctions,normal Auger contribution,half-metallic Co2MnGe,magnetoresistance,Resonant photoelectron spectroscopy,Mn 3d partial DOS,element-speci?c density of states,electrical conductivity
更新于2025-09-11 14:15:04
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Electronic Structures and Ferromagnetic Properties of 3d (Cr)-Doped BaSe Barium Selenide
摘要： In this study, we have employed the first-principle methods based on spin-polarized density functional theory to investigate the structural parameters, the electronic structures, and the half-metallic ferromagnetic behavior of chromium (Cr)-doped barium selenide (BaSe) such as Ba1 ? xCrxSe at concentrations x = 0.25, 0.5, and 0.75. The exchange and correlation potential is described by the generalized gradient approximation of Wu and Cohen (GGA-WC). The calculated structural parameters of BaSe are in good agreement with theoretical data. Our findings reveal that the p-d exchange coupling is ferromagnetic for Ba0.75Cr0.25Se and Ba0.5Cr0.5S, but it becomes anti-ferromagnetic for Ba0.25Cr0.75S. The electronic structures exhibit that the Ba1 ? xCrxSe materials for all concentrations are half-metallic ferromagnets with spin polarization of 100% and total magnetic moment per Cr atom of 4 μB. Therefore, the Ba1 ? xCrxSe compounds are suitable candidates for possible spintronics applications.
关键词： DFT,Cr-doped BaSe,Half-metallic ferromagnetic,Electronic structures
更新于2025-09-09 09:28:46
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Investigation of half-metallic ferromagnetism in hafnium and tantallum doped NiO for spintronic applications: A DFT study
摘要： Full Potential Linearised Augmented Plane Wave (FP-LAPW) method was used to investigate the electronic and magnetic properties of NiO doped with Hf and Ta within the frame work of density functional theory(DFT). NiO is found to be stable in rock salt structure. NiO shows metallic character for the lattice constant of 4.155?. Doping Hf and Ta in the metallic super cell of NiO separately in the doping concentration of 12.5%, the compounds Hf0.125Ni0.875O and Ta0.125Ni0.875O are formed. These compounds of Hf0.125Ni0.875O and Ta0.125Ni0.875O are found to be stable in the ferromagnetic phase. The density of states and band structure plots predict that these compounds exhibit half metallic character with formation of energy gap in one of the spins at the Fermi level. The total spin magnetic moments found in these compounds are 12.00689 μB and 10.97628 μ B.
关键词： DFT,Hf and Ta doping,spintronics,Half-metallic ferromagnetism,NiO
更新于2025-09-09 09:28:46
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Magnetic, half-metallicity and electronic studies of Cd1-xZnxCr2Se4 chromium selenospinels
摘要： We have studied the magnetism of crystalline Cd1-xZnxCr2Se4 spinels with (0.35 ≤ x ≤ 0.55) under magnetic field up to 15 T. The total magnetic moment, Curie temperature, lattice parameter and exchange integrals were found to decrease with Zn substitution. Ab-initio calculations carried out using full potential augmented plane wave (FP-LAPW) method were performed to study the magnetic, and electronic structure using generalized gradient approximation (GGA) and the modified Becke-Johnson (mBJ) to correct the gap’s energy. The obtained results were in good agreement with the experimental ones. It is shown that there is a competition between ferromagnetic (FM) and antiferromagnetic (AFM) interactions: the super-exchange mechanism slightly increases the AFM contribution and keeps the FM the dominant mechanism in this range of substitution. From the density of states, we demonstrate that the system keeps the half-metallic state for the composition range 0.125 ≤ x ≤ 0.55 with 100% spin polarization. Our results highlight that it is possible to obtain a half-metallic semiconductor with tunable magnetic state which is promising for applications in spintronics.
关键词： magnetic competition,half-metallic,DOS,magnetization,mBJ,magnetic moment,Spinels
更新于2025-09-04 15:30:14