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1.
K. Chafai H. Lassri M. Abid E. K. Hlil 《Journal of Superconductivity and Novel Magnetism》2012,25(1):117-123
Magnetic properties of Fe/Ag multilayer films are investigated and examined versus Fe layer thickness t
Fe. As a result, spontaneous magnetization M(T) temperature dependence has been revealed to be well described by a T
3/2 law in all multilayer films (7 ?≤t
Fe≤60 ?). Spin-wave theory based on anisotropic ferromagnetic system has been also used to explain magnetization temperature
dependence. For Fe layer thickness, approximate values for J
0 bulk exchange interaction and J
s
surface exchange interaction have been estimated. First principle calculations based on density functional theory (DFT) and
Korringa–Kohn–Rostoker (KKR)—coherent potential approximation (CPA) method—combined with Local Spin Density Approximation
(LSDA), are performed as well. Magnetic moment, in fcc Ag1−x
Fe
x
and bcc Fe1−x
Ag
x
systems, versus x is presented and discussed in terms of Fe content on magnetic coupling. Reasonable agreement between experimental data and
theoretical calculations is highlighted. 相似文献
2.
In this paper, we have calculated the spin wave gap and the angular dependence of magnetization reversal in a single-layer thin magnetic film that includes the strong perpendicular magnetic anisotropy and in-plane anisotropy. The film is assumed to be under the influence of the out-of-plane direction of the applied magnetic field at zero temperature. Using the quantum model, it is shown that the calculated equations present a nonzero spin wave gap at zero magnetic field which is strongly affected by anisotropies. The effects of the in-plane anisotropy and the role of the applied field were examined. We also discussed a simple theoretical model for the angular variation of switching field by using a quasi-classical argument. We used some constants in connection with experimental data which are reported for chromium telluride thin films grown by molecular beam epitaxy. 相似文献
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以巯基丙酸为稳定剂, 在水相中合成了表面带负电荷、具有良好的分散性、平均粒径为5nm的CdTe量子点. 通过CdTe量子点与阳离子聚电解质聚二烯丙基二甲基氯化铵(PDDA)和阴离子聚电解质聚苯乙烯磺酸钠(PSS)之间的静电相互作用, 在石英基片表面通过层层静电自组装方法制备了多层CdTe量子点纳米薄膜. 以荧光分光光度计、UV-Vis、XPS、AFM等测试手段对所得的CdTe量子点纳米薄膜进行了表征. 研究结果表明, CdTe量子点自组装多层薄膜的UV-Vis吸光度与组装层数基本呈线性关系, 薄膜成膜质量良好. 自组装薄膜基本上规整并均匀地覆盖在石英基底表面, 但薄膜中存在部分CdTe量子点聚集现象. 通过在相邻的两层CdTe量子点之间引入基本结构单元为PDDA/PSS/PDDA的聚电解质复合层, 可有效提高CdTe量子点纳米薄膜的成膜质量. 所得的CdTe量子点纳米薄膜具有良好的荧光光致发光性. 相似文献
5.
Takuro Tomita Ayahito Uetake Tsutomu Asahina Kentaro Kayanuma Akihiro Murayama Yasuo Oka 《Journal of Superconductivity and Novel Magnetism》2005,18(3):405-410
Spin injection processes in the double quantum dots of ZnSe-based diluted magnetic semiconductors are discussed. Double quantum
dots are fabricated from ZnSe-based double quantum wells by electron beam lithography and wet etching. In these samples, the
photo-excited carriers in the magnetic dots are injected into the non-magnetic dots. The circular polarization degrees of
photoluminescence from the non-magnetic dots are measured by micro-photoluminescence measurement system under the magnetic
field up to 5 T. The maximum spin polarization degrees of injected carriers determined from our experiment are 10% for double
quantum wells and 15% for double quantum dots. The spin injection efficiency was estimated both from the observed circular
polarization degree and the diffusion length of carriers. We concluded that the spin injection efficiency is increased in
the double quantum dots. 相似文献
6.
理论分析了传播在层状磁性薄膜开槽波导中的表面静磁波,具体计算了具有不同饱和磁化情况下,表面静磁波传播在开槽波导中的磁场分布和能量分布。 相似文献
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S. Sugai Y. Mizuno R. Watanabe T. Kawaguchi K. Takenaka H. Ikuta K. Kiho M. Nakajima C. H. Lee A. Iyo H. Eisaki S. Uchida 《Journal of Superconductivity and Novel Magnetism》2013,26(4):1179-1183
The electronic and magnetic excitations at the spin density wave (SDW) transition are investigated by Raman scattering. The multi-orbital electronic states induce the Dirac nodes in the SDW gap. The excitations near the nodes and anti-nodes are separately detected in accordance with the two-orbital tight-binding model. The exchange interactions are found to be given by the second derivative of the total energy with respect to the angle of the moment from two-magnon scattering. The two-magnon peak has the large spectral weight above twice the maximum energy of magnon. It is interpreted by the magnetic self-energy of the electron spectral function in the localized spin model or particle-hole excitations in the itinerant spin model. 相似文献
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含自旋—轨道相互作用的碱金属原子的精确量子论 总被引:1,自引:1,他引:0
根据新量子变换理论 ,结合创新的SU(1,1)Lie代数理论及SO(3)Lie代数理论 ,对含自旋—轨道相互作用的碱金属原子的量子力学问题进行系统的研究。结果表明 ,碱金属原子的能级为双能级结构 ,并且是精确的 相似文献
12.
Ferromagnetic resonance (FMR) measurements were carried out on a series of GaMnAs thin films with different thicknesses grown by low temperature molecular beam epitaxy. Clear spin wave resonances were observed in addition to FMR when the applied magnetic field was perpendicular to the film plane. The spin wave spectra show a nearly linear dependence of the resonance mode positions on the mode number, suggesting that the magnetization profile of the GaMnAs films is not uniform in the growth direction. A first-order analysis of these effects is presented along with the experimental data. 相似文献
13.
Kazuki Maruhashi Kei S. Takahashi Mohammad Saeed Bahramy Sunao Shimizu Ryosuke Kurihara Atsushi Miyake Masashi Tokunaga Yoshinori Tokura Masashi Kawasaki 《Advanced materials (Deerfield Beach, Fla.)》2020,32(24):1908315
Magnetic semiconductors are a vital component in the understanding of quantum transport phenomena. To explore such delicate, yet fundamentally important, effects, it is crucial to maintain a high carrier mobility in the presence of magnetic moments. In practice, however, magnetization often diminishes the carrier mobility. Here, it is shown that EuTiO3 is a rare example of a magnetic semiconductor that can be desirably grown using the molecular beam epitaxy to possess a high carrier mobility exceeding 3000 cm2 V−1 s−1 at 2 K, while intrinsically hosting a large magnetization value, 7 μB per formula unit. This is demonstrated by measuring the Shubnikov–de Haas (SdH) oscillations in the ferromagnetic state of EuTiO3 films with various carrier densities. Using first-principles calculations, it is shown that the observed SdH oscillations originate genuinely from Ti 3d-t2g states which are fully spin-polarized due to their energetical proximity to the in-gap Eu 4f bands. Such an exchange coupling is further shown to have a profound effect on the effective mass and fermiology of the Ti 3d-t2g electrons, manifested by a directional anisotropy in the SdH oscillations. These findings suggest that EuTiO3 film is an ideal magnetic semiconductor, offering a fertile field to explore quantum phenomena suitable for spintronic applications. 相似文献
14.
Thickness Dependence of the Quantum Anomalous Hall Effect in Magnetic Topological Insulator Films
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Xiao Feng Yang Feng Jing Wang Yunbo Ou Zhenqi Hao Chang Liu Zuocheng Zhang Liguo Zhang Chaojing Lin Jian Liao Yongqing Li Li‐Li Wang Shuai‐Hua Ji Xi Chen Xucun Ma Shou‐Cheng Zhang Yayu Wang Ke He Qi‐Kun Xue 《Advanced materials (Deerfield Beach, Fla.)》2016,28(30):6386-6390
15.
J. R. Schrieffer 《Journal of Superconductivity》2004,17(5):539-543
The properties of a wide variety of intermetallic compounds exhibiting magnetic localized spin and superconducting fluctuations near a quantum critical point (QCP) are reviewed. They show highly anomalous critical indices (anomalously small). Laws of corresponding are observed in these materials and a theory is presented which gives a fully quantitative explanation of these laws. The theory employs a gauge transformation which rotates the electron spin quantization axis
into the direction of the instantaneous staggered localized spin direction
, where
is the localized spin array wave vector. Many properties of these materials are worked out on the basis of this theory. The technological promise of these substances is truly immense, including energy generation, storage and transmission, MRI magnets, industrial and scientific magnets, maglev, cellular communications, -wave electronics, etc. 相似文献
16.
Tommaso Roscilde Paola Verrucchi Andrea Fubini Stephan Haas Valerio Tognetti 《Journal of Low Temperature Physics》2005,140(3-4):293-302
We perform an extensive quantum Monte Carlo investigation of entanglement properties in quantum spin systems close to or at a quantum critical point. Making use of the Stochastic Series Expansion method, we can systematically estimate the bipartite entanglement of the ground-state wavefunction in a large class of anisotropic spin models on unfrustrated lattices and in a uniform magnetic field. The behavior of the entanglement estimators as a function of the field shows remarkable universal features independent of the lattice dimensionality, marking both the occurrence of a field-induced quantum phase transition and of an exactly factorized state.PACS numbers: 03.67.Mn, 75.10.Jm, 73.43.Nq, 05.30.-d 相似文献
17.
I. A. Shelykh N. T. Bagraev V. K. Ivanov L. E. Klyachkin 《Journal of Superconductivity》2003,16(2):355-356
We present the results of the theoretical analysis of quasi one-dimensional electron gas within the Hartree–Fock approximation. The ground state energy for full polarized and unpolarized states is calculated at T = 0. The formation of spontaneously spin-polarized state at low linear concentration of electrons and its transformation to unpolarized state as concentration increases is discussed. 相似文献
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We present the review of our work on spin effects in single lateral quantum dots with the emphasis on the results of Coulomb blockade spectroscopy studies. Realization of a spin-based quantum bit proposal in a lateral quantum dot is discussed. Described are the ways of isolating a single electron spin in a dot containing only one as well as many electrons. Demonstrated is a current readout of spin transitions in a dot by means of spin blockade spectroscopy due to spin polarized injection/detection mechanism in a lateral dot. Discussed are transitions induced both by changing a magnetic field and a number of electrons in a dot with the emphasis on the effects observed close to filling factor in a dot = 2. 相似文献
20.
In magnetic field, KCuGaF6 can be mapped onto the quantum sine-Gordon model, for which low-energy elementary excitations are solitons, antisolitons and their bound states breathers. Using high-frequency, high-field ESR measurements, we observed these unusual magnetic excitations. 相似文献