共查询到20条相似文献,搜索用时 109 毫秒
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如今在Heusler合金中发现了众多适用于自旋电子学领域的半金属材料及自旋无隙半导体,与此同时也伴随发现了一系列不能简单归类为半金属或金属的材料.为了促进这些化合物在自旋电子学领域的应用,本文提出了一种关于Heusler合金中近半金属性质的评估标准,即当一种材料的带隙在费米能级附近0.30 eV或0.2个电子态以内,具有一定的磁矩且没有高的电导时,可以判定其为近半金属材料.这项标准能够帮助Heusler合金在自旋电子学领域得到更全面地应用,并举一些示例加以说明. 相似文献
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具有高自旋极化率的半金属材料是一类极具应用前景的自旋电子材料.立方BaCrO3具有非常稳定的半金属性,而四方BaTiO3则是一种多功能绝缘体.因此,本研究采用基于密度泛函的第一性原理方法,探究BaTi1-xCrxO3(x=0,0.125,0.25,0.5,0.75,1)体系中Cr、Ti互掺导致的晶体结构和电子结构的变化.研究表明,Cr离子的掺杂会使体系发生四方相到立方相结构相变;同时,受Cr-Ti轨道杂化的影响,体系存在绝缘态-半金属态转变.此外,Cr掺杂调控了体系的磁性,掺入的Cr离子表现为+4价态,提供2μB的局域磁矩.最后,本文构建了d-p杂化分子轨道模型,基本解释了体系半金属性的产生机制.本研究预测了BaTi1-xCrxO3体系中丰富的物理性质,为其在自旋电子器件方面的应用提供了理论指导. 相似文献
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本文基于密度泛函理论的第一性原理方法, 在广义梯度近似(GGA)下计算了掺杂过渡金属Cr原子后AlN晶体自旋极化的能带结构、分态密度等性质. 结果表明, 半金属能隙随着掺杂浓度的增大而减小. 文中以掺杂浓度为12.5%的Cr-AlN(2×2×1)为例, 分析了其自旋极化的能带结构、分态密度和磁矩等性质, 发现Cr-3d电子对自旋向下子带导带底的能量位置起决定作用. 随着掺杂浓度的增大, Cr原子间相互作用增强, Cr-3d能带向两边展宽, 导致自旋向下子带导带底的能量位置下降, 从而半金属能隙变窄. 相似文献
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本文基于密度泛函理论的第一性原理方法, 在广义梯度近似(GGA)下计算了掺杂过渡金属Cr原子后AlN晶体自旋极化的能带结构、分态密度等性质. 结果表明, 半金属能隙随着掺杂浓度的增大而减小. 文中以掺杂浓度为12.5%的Cr-AlN(2×2×1)为例, 分析了其自旋极化的能带结构、分态密度和磁矩等性质, 发现Cr-3d电子对自旋向下子带导带底的能量位置起决定作用. 随着掺杂浓度的增大, Cr原子间相互作用增强, Cr-3d能带向两边展宽, 导致自旋向下子带导带底的能量位置下降, 从而半金属能隙变窄. 相似文献
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采用基于密度泛函理论(DFT)框架下的第一性原理平面波赝势(PWP)方法,结合广义梯度近似(GGA),对三元化合物ZnVSe2晶体的电子结构进行了计算,分析了ZnVSe2晶体自旋极化的能带结构、电子态密度、电荷布居、磁矩等.计算结果表明,三元化合物ZnVSe2会产生自旋极化状态,能带结构和态密度显示为半金属特征,表现出显著的铁磁性行为,具有高达近100%的传导电子自旋极化率,其半金属能隙为0.443eV,理论预测其可能是一种具有一定应用潜能
关键词:
2')" href="#">ZnVSe2
平面波赝势方法
半金属铁磁性
第一性原理 相似文献
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G. Bergmann 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,54(1):19-25
A new method is suggested to investigate the mechanism of the anomalous Hall
effect (AHE) in ferromagnetic metals. Using a double layer of a ferromagnet
and a normal metal of increasing thickness one can manipulate the AHE in the
ferromagnet without changing the ferromagnet's structure and electronic
properties. The conduction electrons from the normal metal carry their drift
velocity across the interface into the ferromagnetic film and induce an
additional AHE conductance ΔGxy. Its dependence on the mean free
path in the normal metal distinguishes between the side jump and the skew
scattering mechanisms for the AHE in the ferromagnet. 相似文献
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In recent years, transition metal borides (TMBs) have attracted much attention because they are considered as potential superhard materials and have more abundant crystal structures compared with traditional superhard materials. So far, however, no superhard materials have been found in TMBs. A large number of structures and potential new properties in TMBs are induced by the various hybridization ways of boron atoms and the high valence electrons of transition metals, which provide many possibilities for its application. And most TMBs have layered structures, which make TMBs have the potential to be a two-dimensional (2D) material. The 2D materials have novel properties, but the research on 2D TMBs is still nearly blank. In this paper, the research progress of TMBs is summarized involving structure, mechanical properties, and multifunctional properties. The strong covalent bonds of boron atoms in TMBs can form one-dimensional, two-dimensional, and three-dimensional substructures, and the multiple electron transfer between transition metal and boron leads to a variety of chemical bonds in TMBs, which are the keys to obtain high hardness and multifunctional properties of TMBs. Further research on the multifunctional properties of TMBs, such as superconductors, catalysts, and high hardness ferromagnetic materials, is of great significance to the discovery of new multifunctional hard materials. 相似文献
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Yasufumi Araki 《Annalen der Physik》2020,532(2):1900287
Recent theoretical and experimental attempts have been successful in finding magnetic Weyl semimetal phases, which show nodal-point structure in the electronic bands as well as magnetic orders. Beyond uniform ferromagnetic or antiferromagnetic orders, nonuniform magnetic textures, such as domain walls and skyrmions, enrich the properties of the Weyl electrons even more in such materials. Here, a topical review on interplay between Weyl electrons and magnetic textures in those magnetic Weyl semimetals is given. The basics of magnetic textures in nontopological magnetic metals are reviewed first, and then the effect of magnetic textures in Weyl semimetals is discussed, regarding the recent theoretical and experimental progress therein. The idea of the fictitious “axial gauge fields” is pointed out, which effectively describes the effect of magnetic textures on the Weyl electrons and can well account for the properties of the electrons localized around magnetic domain walls. 相似文献
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D.J. Kim 《Solid State Communications》1979,30(4):249-252
Starting from a standard electron-phonon interaction model we discuss how the lattice properties depend on the magnetization of conduction electrons in ferromagnetic metals. The simple and sensitive relation between the elastic properties and the electronic structures we obtain might be used to study the electronic structure of ferromagnetic metals. 相似文献
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We have fabricated ferromagnetic/nonmagnetic (FM/NM) metal heterojunctions for the detection of the spin accumulation effect in different nonmagnetic metals. To understand the effect of spin accumulation in more detail, the switching behavior of the ferromagnetic wires was studied by means of magnetoresistance (MR) measurements and Monte Carlo simulations (MC). The polycrystalline heterojunctions were prepared by high-resolution electron beam lithography (HR-EBL) and a special oblique evaporation technique. The ferromagnetic (FM) and the nonmagnetic (NM) metal were evaporated on top of each other in a single-evaporation step to achieve an interface between the two metals of high quality. To verify the quality of the interface, we measured the spin accumulation effect in nonmagnetic copper (Cu) and aluminum (Al) and determined the spin polarization of the current at the interface between the ferromagnetic and nonmagnetic metals. 相似文献
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Elfimov IS Rusydi A Csiszar SI Hu Z Hsieh HH Lin HJ Chen CT Liang R Sawatzky GA 《Physical review letters》2007,98(13):137202
We describe a possible pathway to new magnetic materials with no conventional magnetic elements present. The substitution of nitrogen for oxygen in simple nonmagnetic oxides leads to holes in N 2p states which form local magnetic moments. Because of the very large Hund's rule coupling of Nitrogen and O 2p electrons and the rather extended spatial extent of the wave functions these materials are predicted to be ferromagnetic metals or small band gap insulators. Experimental studies support the theoretical calculations with regard to the basic electronic structure and the formation of local magnetic moments. It remains to be seen if these materials are magnetically ordered and, if so, below what temperature. 相似文献
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采用基于密度泛函理论的第一性原理平面波赝势法计算不同过渡金属(V, Cr, Mn, Fe, Co, Ni)掺杂GaN的电子结构及光学性质,分析掺杂对电子结构及光学性质的影响.结果表明,过渡金属掺杂在GaN的禁带中引入杂质能带,除掺Fe体系外其它掺杂体系都表现为半金属性.除掺Fe和Ni体系在低能区没有出现光吸收外,其它体系均在低能区杂质能级处出现光吸收. 相似文献
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The resistance switching behavior has recently attracted great attentions for its application as resistive random access memories (RRAMs) due to a variety of advantages such as simple structure, high-density, high-speed and low-power. As a leading storage media, the transition metal perovskite oxide owns the strong correlation of electrons and the stable crystal structure, which brings out multifunctionality such as ferroelectric, multiferroic, superconductor, and colossal magnetoresistance/electroresistance effect, etc. The existence of rich electronic phases, metal–insulator transition and the nonstoichiometric oxygen in perovskite oxide provides good platforms to insight into the resistive switching mechanisms. 相似文献
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目前在磁性材料磁有序现象研究中广泛使用的交换作用、超交换作用和双交换作用模型形成于1950年代及其以前,这些模型都涉及材料中的价电子状态,但那时还没有充分的价电子状态实验依据.1970年代以来,有关价电子结构实验结果的报道越来越多,这些实验结果表明传统的磁有序模型需要改进.首先,大量电子谱实验表明,在氧化物中除存在负二价氧离子之外,还存在负一价氧离子,并且负一价氧离子的含量可达30%或更多.这说明以所有氧离子都是负二价离子为基本假设的超交换和双交换作用模型需要改进.其次,一些实验证明,铁、钴、镍自由原子的一部分4s电子在形成铁磁性金属的过程中变成了3d电子,这为探讨金属磁性与电输运性质的关系提供了依据.此外,即使在现代的密度泛函计算中,仍不能给出磁性交换作用能的函数表达式,只能采取各种不同模型进行模拟计算,从而使磁性材料的模拟计算遇到严重困难.寻求一个磁有序能的函数表达式可能是解决这个困难的途径.这些研究表明磁性材料价电子结构研究面临着重大的机遇与挑战.本文首先介绍一些典型的实验例证,然后介绍了基于这些实验结果的一套典型磁性材料的磁有序新模型,随后介绍了基于新模型的磁性材料价电子结构与旧模型的主要区别,最后指出了未来研究工作面临的挑战. 相似文献
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We present a brief survey of the contemporary state of theoretical study of quasiparticles (excited electrons and holes) dynamics in bulk metals and at metal surfaces. Quasiparticle decay mechanisms are discussed in terms of electron-electron (e-e) and electron-phonon (e-ph) interactions. The e-ph decay channel is shown to be important for all materials considered. It is especially important for systems with the thickness of one monolayer. In the e-e decay channel the quasiparticle decay can be realized via one-electron transfer processes, via creation of electron-hole pairs, and via plasmon excitation. In ferromagnetic systems the electron (hole) decay via the Stoner pair excitation or/and magnon excitation is made possible. 相似文献