TDPAC spectrum of111In in a single crystal of cadmium

TDPAC spectra of 111 In in a single crystal of Cd are measured as a function of its. orientation relative to the -direction. The results are compared with the theoretical calculation by Alder et. al.     

Temperature dependence of the reflectance spectrum of the single crystal of tetrathiafulvalene-chloranil

Near-infrared and visible reflectance spectrum was measured on the tetrathiafulvalene-chloranil (TTF-CA) crystal at temperatures in the range of 40–290 K. An abrupt change of reflectivity was found at about 80 K, and new dispersions associated with the intramolecular transitions of TTF⁺ and CA^? gradually grew up on lowering temperature below 80 K, indicating the increase of the ionized fraction.     

Angular dependence of vortex matter phase transition in MgB2 single crystal

The vortex matter phase transitions and intrinsic pinning effect were investigated in an MgB₂ single crystal using the torque magnetometry. For the field directions apart from the ab plane, we succeed in the observation of the vortex lattice melting transitions, which are transformed from the order-disorder transitions at low temperatures. Both transition fields with field directions can be describe by the GL effective mass model. For the field direction along the ab plane, these transitions become unobservable. Instead, the sudden increase in the hysteresis of magnetization curve occurs, indicating the existence of the intrinsic pinning coming from the layer structure.     

Angular dependence of the ferromagnetic resonance spectrum in continuous/heterogeneous multilayers

We present here a study of the angular dependence of the ferromagnetic resonance (FMR) spectra in trilayers formed by two continuous ferromagnetic layers, Fe and Ni₈₀Fe₂₀ (permalloy), separated by a granular film of Fe(x)–SiO₂(1–x). The study of the Fe/Fe-SiO₂/Ni₈₀Fe₂₀ trilayer was made for an Fe volume concentration x=0.75 and two thicknesses (t=1 and 18 nm) of the granular layer. One microwave absorption line is in general found close to the field expected for Fe, while the other is coincident with the resonance field of permalloy. However, the Fe-like absorption is considerably wider than what is usually observed in pure Fe films, which suggests the presence of a strong exchange interaction between this layer and the granular spacer. The angular dependence of the resonance field and the line width could be very well fitted with a model that assumes an effective in-plane anisotropy for each layer, indicating that the shape anisotropy dominates the angular response of both modes. When the excitation frequency is increased, the line width of the permalloy-like mode increases by a similar factor. The width of the Fe-like mode is very similar at different frequencies because of the effect of the granular layer.     

Angular dependence of diffusional broadening of the Mössbauer line in a 57Co—copper single crystal

The angular dependence of the diffusional broadening of the Mössbauer line in a copper single crystal doped with cobalt-57 at 1030°C is obtained experimentally. A qualitative discussion of the results is presented.     

纳米静态随机存储器质子单粒子多位翻转角度相关性研究

器件特征尺寸的减小带来单粒子多位翻转的急剧增加, 对现有加固技术带来了极大挑战. 针对90 nm SRAM(static random access memory, 静态随机存储器)开展了中高能质子入射角度对单粒子多位翻转影响的试验研究, 结果表明随着质子能量的增加, 单粒子多位翻转百分比和多样性增加, 质子单粒子多位翻转角度效应与质子能量相关. 采用一种快速计算质子核反应引起单粒子多位翻转的截面积分算法, 以Geant4中Binary Cascade模型作为中高能质子核反应事件发生器, 从次级粒子的能量和角度分布出发, 揭示了质子与材料核反应产生的次级粒子中, LET(linear energy transfer)最大, 射程最长的粒子优先前向发射是引起单粒子多位翻转角度相关性的根本原因. 质子能量、临界电荷的大小是影响纳米SRAM器件质子多位翻转角度相关性的关键因素. 质子能量越小, 多位翻转截面角度增强效应越大; 临界电荷的增加将增强质子多位翻转角度效应.     

Electron spin resonance spectrum of trapped in a single crystal matrix

The radical , labelled with ¹³C in the position shown, has been prepared by X-irradiation of single crystals of . The ¹³C hyperfine coupling tensor of this radical confirms previous conclusions from a study of the corresponding unlabelled species that the electron is essentially localized on the carbon atom. At room temperature the methylene group undergoes rapid reorientation about the P-C bond while comparison of the ¹³C tensors at 300 K and 77 K suggests that the barrier to rotation has a strong two-fold component but contains intermediate minima.     

3D dependence of the dielectric dispersion in a BaTiO3 single crystal

The 3D dependences ?′(log f, T) and tanδ(logf, T) of a perfect BaTiO₃ single crystal grown by the Remeika method have been studied in the ranges f = 1–2 × 10⁷ Hz and T = ?80–130°C. These dependences characterize a transition from the paraelectric phase (121.5°C) as a near-antiferroelectric transition followed by the transition to the tetragonal phase at ～79.5°C. According to a number of signs, the range 121.5–79.5°C corresponds to a metastable phase typical of first-order phase transitions. The unexpected result of this work has been discussed with invoking the hypothesis on the BaTiO₃ structure in the paraelectric phase, according to which it consists of three antiferroelectric states oriented along the crystallographic axes. Using the dielectric properties of BaTiO₃ as an example, the method of direct correct determination of the temperatures of the structural transformations from the anomaly of tanδ(logf, T) has also been demonstrated.     

Temperature dependence of the magnetoresistance of single crystal aluminium

The magnetoresistance of single crystal aluminium was measured with the magnetic field in the three main crystallographic directions [100], [110] and [111], in the temperature range 4.2–20 K and in magnetic fields up to 7 T. The exponent of a Tⁿ-law is shown to be decreasing with increasing fields.     

Absorption spectrum of VO2+ ion doped in caesium cadmium sulphate hexahydrate single crystal

Results of the optical absorption spectrum of VO²⁺ ion doped in caesium cadmium sulphate hexahydrate studied at room (300 K) and liquid nitrogen (77 K) temperatures are reported. The site symmetry of the ion is found to be C_4ν. Correlating the optical and ESR spectral data, the molecular orbital coefficients are evaluated.     

Angular tuning of defect modes spectrum in the one-dimensional photonic crystal with liquid-crystal layer

A one-dimensional ZrO₂/SiO₂ photonic crystal with a 4-n -pentyl-4' -cyanobiphenyl (5CB) nematic defect layer was used to investigate the transmission spectra of light polarized parallel and perpendicular to the liquid-crystal director at different angles of incidence. The spectra of the photonic crystal were shown to split into four polarized components T_ij at oblique incidence. When the incident angle increased, the bandgap edges and the defect modes shifted towards short wavelengths, while the amplitudes of the defect modes increased for the transverse magnetic polarization and decreased for the transverse electric polarization. The observed discrepancy between the defect mode amplitudes in the center and near the edges of the photonic bandgap was found to be related to the radiation losses inside the defect layer of a non-ideal photonic crystal. The simulated transmission spectra obtained using recurrence relations and taking into account the decay of defect modes are in good agreement with the experimental data.     

Field dependence of Young’s modulus in a gadolinium single crystal

The field dependence of Young’s modulus along the hexagonal c axis is measured in a gadolinium single crystal over a wide range of temperatures and magnitudes of the magnetic field aligned with the c axis. It is found that the isotherms of the field dependence of the ΔE effect in gadolinium are well approximated by a linear dependence on the square of the magnetization in both strong and weak strong magnetic fields, and also above and below the spin reorientation temperature. It is shown that the experimental trends obtained near the ferromagnetic transition can be interpreted within the approach based on the Landau theory of second-order phase transitions. The parameters of such an approach are determined for gadolinium on the basis of the experimental data. Zh. éksp. Teor. Fiz. 114, 2111–2121 (December 1998)     

Angular dependence of proton-induced single event transient in silicon-germanium heterojunction bipolar transistors

We investigate the angular dependence of proton-induced single event transient (SET) in silicon-germanium heterojunction bipolar transistors. Experimental results show that the overall SET cross section is almost independent of proton incident angle. However, the proportion of SET events with long duration and high integral charge collection grows significantly with the increasing angle. Monte Carlo simulations demonstrate that the integral cross section of proton incident events with high ionizing energy deposition in the sensitive volume tends to be higher at larger incident angles, which is associated with the angular distribution of proton-induced secondary particles and the geometry of sensitive volume.     

Temperature dependence of the reflectance spectrum of tetrathiafulvalenium iodide (TTF)I0.71 single crystal

The reflectance spectrum of (TTF)I_0.71 exhibits a Drude-like plasma edge near 10 × 10³ cm^-1, and the reflectivity below this region increases as the temperature is lowered from room temperature to 210 K. However, the near-infrared reflectivity decreases with lowering temperature in the semiconductive phase below 210 K, and an additional peak attributable to the charge transfer between (TTF)⁺ ions grows up as the temperature is lowered. Discussion is given on these behaviors of (TTF)I_0.71.     

Infrared reflectivity spectrum of KTiOPO4 single crystal

The kinetic theory of overlapping phase transformations is a valuable tool in the characterization of diffusion-controlled precipitation reactions. Using this approach, one can obtain the kinetic parameters (n,?k) for simultaneous diffusion-controlled precipitation reactions, based on the knowledge of a specific macroscopic parameter, P(t), chosen to study the ongoing reaction. Both large and small process overlaps are considered. This methodology calculates the kinetic parameters for defined intervals of the fraction-transformed curve rather than for the entire curve. The approach used in this study permits an evaluation of which are the best protocols for the precipitate nucleation and growth rates during tempering reactions in low-alloy steel, whereas an analysis of the total combined transformations data set could lead to erroneous conclusions.