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1.
We calculated the chemical trends of transition metal-doped chalcopyrite DMS (diluted magnetic semiconductors) by the use of KKR–CPA–LDA method. The ferromagnetism was stable in V- and Cr-doped chalcopyrite DMS. In the case of Fe and Co doping, however, the spinglass-like state was realized. On the other hand, in the cases of Mn doped I-III-VI2 and II-IV-V2 type DMS, the ground state was ferromagnetic and spinglass-like, respectively. 相似文献
2.
We investigated the transport and optical properties of diluted magnetic semiconductors theoretically by using a simple model where carriers move in a single band. In this model the carrier feels a nonmagnetic potential at a magnetic impurity site, and its spin interacts with the localized spins of the magnetic impurities through exchange interactions. The electronic states of a carrier were calculated by using the coherent potential approximation (CPA). The magnetism was investigated by minimizing the free-energy and the electrical conductivity was calculated by using the Kubo formula. We examined the results in several typical cases which correspond to (Ga1–xMnx)As with x = 0.05. 相似文献
3.
ZnO是一种宽带隙Ⅱ-Ⅵ族半导体,具有良好的光电耦合特性和稳定性,在光、电、磁功能集成等新型器件方面可获得重要应用.近来的研究表明,过渡金属掺杂的ZnO基半导体有望成为实现高居里温度稀磁半导体的候选材料,是目前研究的热点.总结了近几年人们在Fe、Co、Ni、Cu、Mn等过渡金属掺杂的ZnO基稀磁半导体的发光特性研究结果,讨论了过渡金属掺杂后ZnO中观察到的可见发光机制,分析认为过渡金属掺杂ZnO的可见光发射主要与这些发光过渡金属引入后所产生的缺陷有关,而紫外发光峰的变化则与过渡金属掺入后ZnO晶体质量与禁带宽度的改变相关. 相似文献
4.
采用电化学沉积法,在氧化铝模板中成功制备了直径50nm的Fe纳米线的高度有序阵列。纳米线的结构和磁学特性分别用透射电子显微镜(TEM),扫描电子显微镜(SEM),X射线衍射仪(XRD)和振动样品磁力计(VSM)测试。结果表明,Fe纳米线是以fcc结构存在。当外加磁场与纳米线的线轴平行时,测得的矫顽力为21000e,剩磁比为0.89,而当外加磁场与纳米线线轴垂直时,所测得的矫顽力仅为1600e,剩磁比为0.2。这表明纳米线阵列具有明显的各向异性,纳柴癌的易妯方向为纳粜姥姥妯方向. 相似文献
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R. Masrour E. K. Hlil M. Hamedoun A. Benyoussef O. Mounkachi H. El Moussaoui 《Journal of Superconductivity and Novel Magnetism》2014,27(11):2581-2584
Self-consistent ab initio calculations, based on density functional theory (DFT) approach and using full-potential linear augmented plane wave (FLAPW) method, are performed to investigate both electronic and magnetic properties of the MnAu nanowire. Polarized spin and spin-orbit coupling are included in calculations within the framework of the antiferromagnetic state between two adjacent Mn layers in MnAu nanowire. Magnetic moments considered to lie along the c-axes are computed. Obtained data from ab initio calculations are used as input for the high temperature series expansions (HTSEs) calculations to compute other magnetic parameters. The zero-field high temperature static susceptibility series of the magnetic moment (m) and nearest neighbour Ising model on a MnAu nanowire is thoroughly analyzed by means of a power series coherent anomaly method (CAM) for different layers. The exchanges interactions between the magnetic atoms, the critical exponent associated with the magnetic susceptibility are obtained for MnAu nanowire with different layers. 相似文献
7.
S. Salimian S. Farjami Shayesteh 《Journal of Superconductivity and Novel Magnetism》2012,25(6):2009-2014
Diluted magnetic CdS:Mn nanoparticles were synthesized by the aqueous solution method with different manganese (Mn2+) concentrations (x=7?C10?atom?%) at room temperature in nitrogen atmosphere and capped with Thiogelycerol. The X-ray diffraction patterns of CdS nanoparticles with different Mn doping concentration indicated that samples have hexagonal structure at room temperature. Energy dispersive X-ray spectroscopy confirmed incorporative of Mn ions in CdS nanoparticles. UV-Visible spectroscopy is used to investigate optical absorption of Mn-doped CdS. From photoluminescence measurement it was found that the intensity of the luminescence spectra decreases by increasing Mn2+ dopant ions at high precursor concentration. Also, the room temperature ferromagnetic behavior of Mn-doped CdS nanoparticles is discussed by using hysteresis measurement results. 相似文献
8.
V. Fallahi M. Ghanaatshoar N. Tajielyato 《Journal of Superconductivity and Novel Magnetism》2013,26(5):1759-1763
We have investigated the influence of spin accumulation on the domain wall resistance in the presence of the Rashba and the Dresselhaus spin–orbit interactions. In this order, we have employed a quantum kinetic model based on the Wigner distribution function formalism. Using the single-electron Hamiltonian and following the approach of ?imánek and Rebei (Phys. Rev. B 71:172405, 2005), we derive the coupled differential equations for transverse spin accumulation components and then calculate its contribution to the resistance of a domain wall. The results show that both the Rashba and the Dresselhaus spin–orbit interactions enhance the transverse spin accumulation and consequently increase the domain wall resistance. 相似文献
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We report the magnetic and magnetotransport properties of Ga1−x
Mn
x
Sb crystals grown with different Mn doping concentrations (x=0.01, 0.02, 0.03 and 0.04) by the horizontal Bridgman technique. A systematic reduction in lattice parameter with increase
in Mn concentration is observed through X-ray diffraction studies. The crystals show negative magnetoresistance and anomalous
Hall effect below 10 K. Anomalous Hall coefficient is negative and decreases with increasing Mn concentration. Temperature
dependence on magnetization measurement shows a magnetic ordering below 10 K which could arise from GaMnSb alloy formation.
Also, ferromagnetism is observed till room temperature due to the presence of MnSb clusters. Existence of MnSb clusters is
verified through scanning electron microscopy. The carrier concentration increases with Mn doping and this results in decrease
of resistivity. The observed magnetic and transport properties indicate the presence of ferromagnetic phase below 10 K in
the studied system.
相似文献
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Babak Jaleh Fatemeh Koosha Afshan Omidvar Dezfuli 《Journal of Superconductivity and Novel Magnetism》2014,27(4):1065-1071
Ni/Pd multilayer nanowire arrays have been electrodeposited into the nanochannels of porous polycarbonate (PC) template. Current–time profiles obtained during the deposition process were analyzed to understand the mechanism of growth. Synthesized nanowires were fully characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), and scanning electron microscopy (SEM). The X-ray diffraction pattern showed that Pd and Ni grow in their face-centered-cubic (FCC) structures. Each nanowire had the same length of ≈4 μm and a diameter of 90 nm. The magnetic properties of the prepared nanowires are different under different electrodepositing conditions. A vibration sample magnetometer (VSM) was used to determine the effect of the Pd content on magnetic properties of final products. 相似文献
13.
M. Sakuma K. Hyomi I. Souma A. Murayama Y. Oka 《Journal of Superconductivity and Novel Magnetism》2005,18(3):325-329
Giant Zeeman effects of excitons were studied in hybrid nanostructures of diluted magnetic semiconductor (DMS) quantum wells
(QWs) with ferromagnetic Co, where the DMS-QW wires with the width of 200 nm were sandwiched in the Co wires with the width
of 400 nm. When the direction of the Co magnetization is normal to the wire plane, a magnetic field B
⊥
Co‐flux perpendicular to the well plane can be applied from the Co wires to all of the DMS-QW wire. In addition, the use of a Co/Pt
multilayered film with the perpendicular magnetization at zero external field was examined instead of the pure Co film. The
excitonic photoluminescence spectrum from the DMS-QW shows significant broadening in the hybrid structures, indicating the
giant Zeeman shift of excitons induced by B
⊥
Co‐flux. 相似文献
14.
主要介绍了AlN基稀磁半导体(DMS)的研究进展,包括其发展过程、AlN基DMS的研究现状,描述了理想的AlN基DMS材料应具备的特征,并展望了其未来的研究方向. 相似文献
15.
Alirezaei B. Samanifar S. Ghasemi A. Rashidi A. J. Paimozd E. 《Journal of Superconductivity and Novel Magnetism》2021,34(12):3199-3208
Journal of Superconductivity and Novel Magnetism - The better understanding of magnetization reversal in impurity added magnetic nanowires (NWs) would allow for their efficient use in future... 相似文献
16.
采用二步阳极氧化法制备孔结构高度有序的多孔氧化铝(AAO)模板。在不同Fe2+/Co2+摩尔比的电解液中,利用交流电化学沉积,在模板孔内成功制备了FeCo合金纳米线阵列。分别采用透射电子显微镜(TEM),场发射扫描电子显微镜(FE-SEM),X射线衍射仪(XRD)和震动样品磁强计(VSM)对样品的形貌,结构及磁学性能进行了表征。结果表明,制备的FeCo合金纳米线排列有序,粗细均匀;其直径与模板孔径一致,填充率较高,且具有明显的[110]择优取向。VSM测试结果表明,不同溶液浓度下制备的FeCo合金纳米线阵列均具有良好的垂直磁各向异性,易磁化轴沿着纳米线轴线方向。随着电解液Fe2+/Co2+摩尔比的不同,可在一定范围内对FeCo合金纳米线阵列的磁性进行调控,并对其原因进行了讨论。 相似文献
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分别采用固相烧结法及激光液相烧蚀(LAL)技术,成功制备出Co掺杂CeO_2稀磁氧化物陶瓷块体和纳米颗粒。XRD和SEM研究发现所制备的材料具有良好的结晶性和形貌。Co掺杂CeO_2稀磁氧化物陶瓷块体和纳米颗粒均为多晶立方结构,与纯立方相的CeO_2结构相同,说明Co掺杂未形成其他结构和杂相。磁性测量表明固相烧结法和激光烧蚀液相法制备的Co掺杂CeO_2样品均具有较高的室温铁磁性,且远高于文献中报道的结果。将陶瓷块材经激光烧蚀成纳米颗粒后,纳米颗粒的铁磁性与陶瓷块材保持一致。这说明激光烧蚀法制备的纳米材料可以很好地保持母材的特性,是一种很好的纳米颗粒制备方法。根据XRD和SEM研究结果,笔者认为Co掺杂CeO_2陶瓷块材及纳米颗粒的室温铁磁性是内禀性质;磁性产生的机理源于氧空位诱导的铁磁性耦合。 相似文献
19.
O. Mounkachi M. Boujnah H. Labrim M. Hamedoun A. Benyoussef A. El Kenz M. Loulidi B. Belhourma M. Bhihi E. K. Hlil 《Journal of Superconductivity and Novel Magnetism》2012,25(5):1515-1521
Structural and magnetic properties of Zn0.8(Fe0.1, Co0.1)O bulk diluted magnetic semiconductor have been investigated using X-ray diffraction (XRD) and magnetic measurements. TEM (Transmission Electron Microscopy) images confirmed the high crystallinity and grain size of Zn0.8(Fe0.1,Co0.1)O powder, the samples were characterized by energy dispersive spectroscopy (EDS) to confirm the expected stoichiometry. This sample has been synthesized by co-precipitation route. The study of magnetization hysteresis loop measurements infers that the bulk sample of Zn0.8(Fe0.1,Co0.1)O shows a well-defined hysteresis loop at T c (200?K) temperature, which reflects its ferromagnetic behavior. Hydrogenation treatment was used for the control of phase separation. Based on first-principles spin-density functional calculations, using the Korringa?CKohn?CRostoker method (KKR) combined with the coherent potential approximation (CPA), the ferromagnetic state energy was calculated and compared with the local-moment-disordered (LMD) state energy. The mechanism of hybridization and interaction between magnetic ions in Zn0.8(Fe0.1,Co0.1)O is also investigated. 相似文献