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1.
考虑界面粗糙散射,在Blonder-Tinkham-Klapwijk(BTK)理论框架下,通过求解Bogoliubov-de-Gennes(BdG)方程,分别计算T=0K和有限温度下,d(x2-y2)+idxy混合波正常金属绝缘层超导体结中的准粒子输运系数和隧道谱.研究表明:隧道谱中的电导峰的劈裂程度强烈地依赖于dxy波分量的强度、超导体的晶轴方位和界面粗糙强度,而温度的升高能压低电导峰.
关键词:
NIS结
(x2-y2)+idxy混合波超导体')" href="#">d(x2-y2)+idxy混合波超导体
隧道谱 相似文献
2.
3.
Differential conductance in normal-metal/insulator/metal/d-wave superconductor junction carrying a supercurrent
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This paper applies the Bogoliubov--de Gennes equation and
the Blonder--Tinkham--Klapwijk approach to study the oscillatory
behaviour of differential conductance in a normal metal/insulator/metal/d-wave
superconductor junction carrying a
supercurrent Is. We find that (i) a three-humped structure
appears at a nearly critical supercurrent Is and z ≈
0.5 for the normal metal/insulator/metal/d_x2 + y2-wave
superconductor junction; (ii) the zero-bias conductance peak splits
into two peaks with sufficiently large applied current for the normal
metal/insulator/metal/dxy-wave superconductor junction; (iii)
the conductance spectrum exhibits oscillating behaviour with the
bias voltage and the peaks of the resonances are suppressed by
increasing supercurrent Is. 相似文献
4.
Analytical potential energy function for the electronic states 2^∏1/2 and 2^∏3/2 of O^x2 (x=+1, -1)
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The splitting of potential energy levels for ground state X^2∏g of O^x2 (x = +1,-1) under spin-orbit coupling (SOC) has been calculated by using the spin-orbit (SO) multi-configuration quasi-degenerate perturbation theory (SO-MCQDPT). Their Murrell-Sorbie (M S) potential functions are gained, and then the spectroscopic constants for electronic states 2^∏1/2 and 2^∏3/2 are derived from the M S function. The vertical excitation energies for O^x2 (x = +1,-1) are v[O2+1^(2∏3/2→X^2∏1/2)] =195.652cm^-1, and v[O2^-1(2^∏1/2 →X^2∏3/2)] =182.568cm^-1, respectively. All the spectroscopic data for electronic states 2^∏1/2 and 2^∏3/2 are given for the first time. 相似文献
5.
Eu2+-doped Sr3Al2O6 (Sr3−xEuxAl2O6) was synthesized by a solid-state reaction under either H2 and N2 atmosphere or CO atmosphere. When H2 was used as the reducing agent, the phosphor exhibited green emission under near UV excitation, while CO was used as the reducing agent, the phosphor mainly showed red emission under blue light excitation. Both emissions belong to the d-f transition of Eu2+ ion. The relationship between the emission wavelengths and the occupation of Eu2+ at different crystallographic sites was studied. The preferential substitution of Eu2+ into different Sr2+ cites at different reaction periods and the substitution rates under different atmospheres were discussed. Finally, green-emitting and red-emitting LEDs were fabricated by coating the phosphor onto near UV- or blue-emitting InGaN chips. 相似文献
6.
《Superlattices and Microstructures》1999,25(5-6)
Recently, there has been tremendous interest on a tunneling feature called zero bias conductance peak (ZBCP) commonly found in high Tcsuperconductor tunnel junctions. The interest stemmed from the feature’s root in the d-wave symmetry of high Tcsuperconductors. In this paper we will review results of our study on ZBCP within a Pb/Bi2Sr2CaCu2O8(BSCCO) tunneling junction. This allows us to investigate the intricate interactions between s- and d-wave superconductivity. The ZBCP indeed demonstrates interesting properties when Pb becomes superconducting. We attribute these results to the suppression of the d-wave phase on the surface of BSCCO by the s-wave superconductivity from Pb through a proximity effect. We will also report some recent results on the magnetic field dependence of the ZBCP. 相似文献
7.
Based on the density functional theory(DFT),using the scheme of the linearized augmented plane wave and the improved local orbital(APW + lo),the structure,the electronic bands and the magnetism of superconducting compounds Ca1-xKxFe2As2(x = 0,0.25,0.5,0.75,1) are optimized and calculated.The calculation results indicate that with K-doping the lengths of the a,b axes can decrease,and the length of the c axis,the volume,the energy of spin-down valence bands,and the DOS at the Fermi level can increase,which leads the magnetic moment of the system to increase. 相似文献
8.
9.
N. Srinivasa RaoP. Raghava Rao Y. GandhiCh. Srinivasa Rao G. Sahaya BaskaranV. Ravi Kumar N. Veeraiah 《Physica B: Condensed Matter》2011,406(23):4494-4499
Lead bismuth arsenate glasses mixed with different concentrations of WO3 (ranging from 0 to 6.0 mol%) were synthesized. Differential thermal analysis (DTA), optical absorption, ESR and IR spectral studies have been carried out. The results of DTA have indicated that there is a gradual decrease in the resistance of the glass against devitrification with increase in the concentration of WO3 upto 4.0 mol%.The optical absorption spectra of these glasses exhibited a relatively broad band peaking at about 880 nm identified due to dxy→dx2−y2 transition of W5+ ions; this band is observed to be more intense in the spectrum of glass containing 4.0 mol% of WO3. Further, two prominent kinks attributed to 3P0→1S0, 1D2 transitions of Bi3+ ions have also been located in the absorption spectra. The ESR spectra of these glasses recorded at room temperature exhibited an asymmetric signal at g⊥∼1.71 and gll∼1.61. The intensity of the signal is observed to be maximal for the spectrum of the glass W4. The quantitative analysis of optical absorption and ESR spectral studies have indicated that there is a maximum reduction of tungsten ions from W6+ state to W5+ state in the glass containing 4.0 mol% of WO3. The IR spectral studies have indicated that there is a increasing degree of disorder in the glass network with increase in the concentration of WO3 upto 4.0 mol%. 相似文献
10.
A series of green phosphors Zn1.92−2xYxLixSiO4:0.08Mn2+ (0≤x≤0.03) were prepared by solid-state synthesis method. Phase and lattice parameters of the synthesized phosphors were characterized by powder X-ray diffractometer (XRD) and the co-doped effects of Y3+/Li+ upon emission intensity and decay time were investigated under 147 nm excitation. The results indicate that the co-doping of Y3+/Li+ has favorable influence on the photoluminescence properties of Zn2SiO4:Mn2+, and the optimal photoluminescence intensity of Zn1.90Y0.01Li0.01SiO4:0.08Mn2+ is 103% of that of commercial phosphor when the doping concentration of Y3+/Li+ is 0.01 mol. Additionally, the decay time of phosphor is much shortened and the decay time of Zn1.90Y0.01Li0.01SiO4:0.08Mn2+ is 3.39 ms, shorter by 1.83 ms than that of commercial product after Y3+/Li+ co-doping. 相似文献
11.
12.
To investigate the upconversion emission,this paper synthesizes Tm3+ and Yb3+ codoped Y2O3 nanoparticles,and then coats them with TiO2 shells for different coating times.The spectral results of TiO2 coated nanoparticles indicate that upconversion emission intensities have respectively been enhanced 3.2,5.4,and 2.2 times for coating times of 30,60 and 90 min at an excitation power density of 3.21×102 W.cm 2,in comparison with the emission intensity of non-coated nanoparticles.Therefore it can be concluded that the intense upconversion emission of Y2O3:Tm3+,Yb3+ nanoparticles can be achieved by coating the particle surfaces with a shell of specific thickness. 相似文献
13.
根据密度波理论建立了stage-2有序LixTiS2(x=1/8,1/6,1/4,1/3,3/8,1/2)系统的晶胞模型.采用平面波赝势方法,对stage-2有序系统和stage-1有序LixTiS2(x=0,1/4,1/3,1/2,2/3,3/4,1)系统进行了几何结构优化和总能量计算,并进行了对比研究.发现stage-2晶胞的参量c(d
关键词:
xTiS2')" href="#">LixTiS2
阶梯结构
有序—无序相变
第一性原理计算 相似文献
14.
通过固相反应法制备了Er3+/Yb3+共掺杂ZrO2-Al2O3粉末的样品,并对样品在980nm激光激发下的上转换发光特性进行了研究.从发射光谱可以发现,在可见光范围内有3个强的发光带,一个位于654nm附近的红光带和两个分别位于545nm、525nm附近的绿光带,分别对应于Er3+离子的以下辐射跃迁:4F9/2→4I15/2、4S3/2→4I15/2、 2H11/2→4I15/2.其中又以Er3+离子的4F9/2→4I15/2跃迁产生的红色荧光辐射最强.对其上转换发光机制进行了分析,发现这三个发光过程都是双光子过程.对样品粉末进行了XRD检测,发现ZrO2主要以立方相为主,并且计算得到了这种立方结构的晶格常数.Al2O3固溶于ZrO2中,Al3+嵌入ZrO2后产生氧空位,导致ZrO2晶体的对称性降低,这种结构变化更有利于提高上转换效率,即上转换发光强度增强.
关键词:
3+/Yb3+')" href="#">Er3+/Yb3+
上转换
2-Al2O3')" href="#">ZrO2-Al2O3
荧光
稀土 相似文献
15.
The spin Hamiltonian parameters, g factors gi (i = x, y, z) and the hyperfine structure constants Ai for the interstitial Mo5+ centre in rutile TiO2 are quantitatively investigated from the perturbation formulas of these parameters for a 4d1 ion in rhombically compressed octahedra. From the studies, the local compression parameter τ′ (≈0.024) and the rhombic distortion angle δ?′ (≈1.74°) around the impurity Mo5+ are smaller than the host values (≈0.091 and 3.5°). This means that the oxygen octahedron in the impurity centre has less rhombic distortion than that on the host interstitial site due to the Jahn–Teller effect and occupation of the impurity. The above local lattice distortion of the studied impurity centre is also discussed. 相似文献
16.
P掺杂对绿色荧光粉BaMgAl$lt;sub$gt;10$lt;/sub$gt;O$lt;sub$gt;17$lt;/sub$gt;:Mn$lt;sup$gt;2+$lt;/sup$gt;性能的影响
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采用高温固相法合成P掺杂的BaMgAl10O17:Mn2+荧光粉,其中P通过(NH4)2HPO4引入.利用X射线衍射谱、傅里叶变换红外光谱、扫描电子显微镜、能量色散谱、真空紫外光谱等研究了P掺杂对BaMgAl10O17:Mn2+晶体结构、微观形貌、发光性能等的影响.研究结果表明:(NH4)2HPO4具有助熔剂的作用,它的加入有助于荧光粉的晶化,改善荧光粉的形貌.P掺杂进入晶格,使得晶胞参数变小,从而改变了Mn2+的晶体场环境,引起发射光谱蓝移,色坐标x值降低.P掺杂能有效提高基质对真空紫外线的吸收,从而提高真空紫外激发下的发光强度.
关键词:
P掺杂
10O17:Mn2+')" href="#">BaMgAl10O17:Mn2+
晶体结构
真空紫外 相似文献
17.
Kenta Nagamine Keita Hirose Tsuyoshi Honma Takayuki Komatsu 《Solid State Ionics》2008,179(13-14):508-515
The glasses with the composition of 37.5Li2O–(25 − x)Fe2O3–xNb2O5–37.5P2O5 (mol%) (x = 5,10,15) are prepared, and it is found that the addition of Nb2O5 is effective for the glass formation in the lithium iron phosphate system. The glass–ceramics consisting of Nasicon-type Li3Fe2(PO4)3 crystals with an orthorhombic structure are developed through conventional crystallization in an electric furnace, showing electrical conductivities of 3 × 10− 6 Scm− 1 at room temperature and the activation energies of 0.48 eV (x = 5) and 0.51 eV (x = 10) for Li+ ion conduction in the temperature range of 30–200 °C. A continuous wave Nd:YAG laser (wavelength: 1064 nm) with powers of 0.14–0.30 W and a scanning speed of 10 μm/s is irradiated onto the surface of the glasses, and the formation of Li3Fe2(PO4)3 crystals is confirmed from XRD analyses and micro-Raman scattering spectra. The crystallization of the precursor glasses is considered as new route for the fabrication of Li3Fe2(PO4)3 crystals being candidates for use as electrolyte materials in lithium ion secondary batteries. 相似文献
18.
The structure and magnetic properties of Y2Fe16Al compound have been investigated by means of x-ray diffraction and magnetization measurements. The Y2Fe Fe16Al compound has a hexagonal Th$_{2}$Ni$_{17}$-type structure. Negative thermal expansion was found in Y2Fe16Al compound in the temperature range from 332 to 438K by x-ray dilatometry. The coefficient of the average thermal expansion is \alpha =-3.4\times 10-5K-1. The spontaneous magnetostrictive deformations from 293 to 427K have been calculated based on the differences between the experimental values of the lattice parameters and the corresponding values extrapolated from the paramagnetic range. The result shows that the spontaneous volume magnetostrictive deformation \textit{$\omega $}$_{\rm S}$ decreases from 5.4$\times $10-3to near zero with temperature increasing from 293 to 427K, the spontaneous linear magnetostrictive deformation \textit{$\lambda $}$_{\rm c}$ along the $c$ axis is much larger than the spontaneous linear magnetostrictive deformation \textit{$\lambda $}$_{\rm a}$ in basal-plane in the same temperature range except near 427K. 相似文献
19.
A novel green phosphor, Tb3+ doped Bi2ZnB2O7 was synthesized by conventional solid state reaction method. The phase of synthesized materials was determined using the XRD, DTA/TG and FTIR. The photoluminescence characteristics were investigated using spectrofluorometer at room temperature. Bi2ZnB2O7:Tb3+ phosphors excited by 270 nm and 485 nm wavelengths. The emission spectra were composed of three bands, in which the dominated emission of green luminescence Bi2ZnB2O7:Tb3+ attributed to the transition 5D4 → 7F5 is centered at 546 nm. The dependence of the emission intensity on the Tb3+ concentration for the Bi2−xTbxZnB2O7 (0.01 ≤ x ≤ 0.15) was studied and observed that the optimum concentration of Tb3+ in phosphor was 13 mol% for the highest emission intensity at 546 nm. 相似文献
20.
In this work, the complete matrix of optical spectral levels in trigonal symmetry of 3d2 (3d8) ions are established on basis of strong field coupling mechanism by using two spin–orbit coupling parameters model. The contribution of the spin–orbit coupling of ligand to the optical spectra has been included in these formulas. As an application, the optical spectra of Cr4+ in Y2Ti2O7 and Y2Sn2O7 have been studied by the complete diagonalization (energy matrix) method. The covalent effect has been studied and the difficulty about Dq parameter in explanation of optical spectra of Cr-doped Y2Ti2O7 and Y2Sn2O7 is removed. The theoretical results are in good agreement with observed data. 相似文献