Josephson effect between p-wave superconductors with different orbital pairing symmetries

The Josephson effects in the ferromagnetic superconductor junctions of the equal spin pairing symmetry are investigated by a Furusaki–Tsukada-like formula. It is shown that the internal phase difference between the two different anisotropic superconductors plays an important role on the Josephson current. The current is predicted to be an oscillation function of the macroscopic phase difference with the period 2π, π, or π/2 depending on the different orbital pairing symmetries of the superconductors of the junction.     

Zeeman effects on d-wave superconductor and tunneling spectrum in normal-metal/d-wave superconductor tunnel junction

We study the Zeeman effect on the d-wave superconductor and tunneling spectrum in normal-metal(N)/d-wave superconductor(S) junction by applying a Zeeman magnetic field to the S. It is shown that: (1) the Zeeman magnetic field can lead to the S gap decreasing, and with the increase in Zeeman energy, the superconducting state is changed to the normal state, exhibiting a first-order phase transition; (2) the Zeeman magnetic field may make the zero-bias conductance peak split into two peaks, and the energy difference between the two splitting peaks in the conductance spectrum is equal to 2h ₀ (h ₀ is the Zeeman energy); (3) both the barrier strength of interface scattering and the temperature can lower the magnitudes of splitting peaks, of which the barrier strength can lead to the splitting peaks becoming sharp and the temperature can smear out the peaks, however, neither of them can influence the Zeeman effect.     

新型超导材料MgCNi3的电子结构与超导电性研究

用MS-Xα方法研究了非氧化物超导材料MgCNi₃的电子结构. 研究结果显示, 态密度分布曲线的主峰靠近Fermi面, 主要来自于Ni的d电子的贡献. 用T(T=Co，Mn，Cu)替代MgCNi₃中的部分Ni形成化合物MgCNi₂T，替代使Ni的价电子数减小, 价态发生变化, Fermi面处态密度N(E_F)减小. 计算结果表明：无论是电子掺杂（Cu）还是空穴掺杂（Co，Mn），MgCNi₃的超导电 关键词： 电子结构 态密度 超导电性     

Lattice strain and p-d repulsion affecting electronic structure of wurtzite Zn1-xCdxO alloys

In the paper, density of states, band structure and electron density difference of Zn1-xCdxO are calculated by first principles, here x varies from 0 to 0.75 at intervals of 0.125, and the band gap obtained from band structure changes from 0.968 eV to 0.043 eV. The lattice strain and p-d repulsion theory are used to investigate variation of the band gap, the results obtained show that the variation is mainly due to the lattice tensile strain. The p-d repulsion in Zn1-xCdxO cannot be neglected. In addition, electron density difference can be used to verify the results.     

Spectral characteristics of the impurity band in the structural disorder model

The density and character of the quantum states in the impurity band arising from broadening of the local impurity level are studied. When the impurity concentration is small, the energy levels and states in the impurity band admit an apparent geometric systematics in the main approximation. In this systematics, the wave functions are localized at one or two centers, though the energy levels depend on the positions of orther centers. The density of states and the space correlators calculated in the main approximation are of universal nature, i.e., are represented in a certain scale as universal functions independent of the concentration. In the immediate vicinity of the local level, where in terms of the geometric systematics the density of states has a gap, different states become significant, which collectivize a larger number of centers. They fill the gap, the filling degree essentially depending on the impurity concentration. The general structure of the impurity band spectrum is discussed.     

Study on the p-type QWIP-LED device

A p-type quantum well infrared photodetector (QWIP) integrated with a light-emitting diode (LED) (named QWIP-LED) was fabricated and studied. The infrared photo-response spectrum was obtained from the device resistance variation and the near-infrared photo-emission intensity variation. A good agreement between these two spectra was observed, which demonstrates that the long-wavelength infrared radiation around 7.5 μm has been transferred to the near-infrared light at 0.8 μm by the photo-electronic process in the QWIP-LED structure. Moreover, the experimentally observed infrared response wavelength is in good agreement with the theoretical calculation value of 7.7 μm. The results on the upconversion of the infrared radiation will be very useful for the new infrared focal plane array technology.     

Non-magnetic impurity effect in two-gap superconductor Lu2Fe3Si5

We report detailed study of non-magnetic impurity effects in a two-gap superconductor Lu₂Fe₃Si₅ by replacing Lu with Sc. We find that the superconducting transition temperature T_c is drastically suppressed by slight substitution of Sc, while lattice constants change linearly with the substitution. These results strongly indicate that a slight substitution of Sc increases the inter-band scattering and causes averaging the amplitude of two gaps, which leads to the drastic suppression of T_c.     

Measuring the optical parameters of thin films by p-polarized laser beams

The refractive index n_f, extinction coefficient k_f and thickness d_f of a dip coated film are measured by using p-polarized laser beams. A sample is oblique illuminated with a p-polarized laser beam, and then two reflected beams, from the front and back surfaces, are received with a detector. After measuring their intensity ratio versus the angle of incidence, it is convenient to obtain the parameters of the film by means of data fitting. The films of polymethyltriethoxy silane (PMTES), which were made on a BK-7 glass substrate by dip coating, were measured. The method is non-contact, non-destructive and has the advantages of simplicity of both equipment and understanding. It is also shown that the values measured by this method are coincident with those measured by ellipsometry.     

The (γ,p) reaction in Au

Proton energy spectra of the ¹⁹⁷Au(e,p) reaction were measured in the region between 17 and 30 MeV at three angles: 40°, 90° and 140°. Two prominent bumps were observed in the (γ,p) spectra converted using virtual photon theory. The higher-energy bump shifts with photon energies and the lower-energy one stays at 10.5 MeV. The higher-energy bump is much larger at 40° than at 140°; on the contrary the angular dependence of the lower-energy bump is small. Neither bump can be described by a statistical calculation. A calculation of a microscopic shell model shows that the lower-energy bump is attributed to the decay of proton-particle–neutron-hole pairs in the T_> states, leaving a neutron hole around the Fermi surface. The higher-energy bump can be ascribed to the direct–semidirect mechanism. This paper gives the solution to a part of the long-standing question about the origin of photo-proton emission in heavy nuclei.     

Extended triplet set C343 of DNA sequences and its application to the p53 gene

Recently, much research has indicated that more and more cancers pose a threat to human life. Cancers are caused by oncogenes. Many human oncogenes have been found and most of them are located on chromosomes. The discovery of the oncogene plays a significant role in the treatment of cancer. The p53 tumor suppressor gene has received much attention because it frequently mutates or deletes in tumor cells of most people. Thus, the study of oncogenes is significant. In order to establish the Galois field (GF(7)), the indefinite gene is introduced as D and oncogene is introduced as O, and P. Taking the polynomial coefficients a₀, a₁, a₂ ∈ GF(7) and the bijective function f:GF(7) → {D,A,C,O,G,T,P}, where f(0) = D, f(1) = A, f(2) = C, f(3) = O, f(4) = G, f(5) = T, and f(6) = P, the bijective φ may be written as φ(a₀ + a₁x + a₂x²). Based on the algebraic structure, we can not only analyse the DNA sequence of oncogenes, but also predict possible new cancers.     

载流子在金属/聚对苯乙炔/金属结构中注入及输运的动力学研究

采用紧束缚的Su-Schrieffer-Heeger模型,利用非绝热动力学方法研究了载流子在金属/聚对苯乙炔(poly(p-phenylene vinylene,简记为PPV))/金属三明治结构中注入与输运的动力学过程.发现由于强的电子-晶格相互作用,注入的电荷在PPV链中形成波包,波包的形成与施加在金属电极上的偏压、PPV链上的电场强度及金属电极与PPV之间的界面耦合强度密切相关.在无外电场的情况下,当偏压达到临界值时电荷能够从金属电极注入到PPV链中并形成波包.随着电场强度的增大,波包能 关键词： 金属/聚对苯乙炔/金属结构 载流子输运 波包     

Reduction dependence of superconductivity in the end-member T′ cuprates

We have recently achieved superconductivity in T′-RE₂CuO₄ (RE: Pr, Nd, Sm, Eu, and Gd), using epitaxial thin films by metal organic decomposition. The key recipes to achieve superconductivity are low-P_O2 firing and subsequent vacuum reduction to minimize the amount of impurity oxygen atoms, which are very harmful to high-T_c superconductivity. In this article, we report our investigation on the reduction dependence of superconductivity of T′-RE₂CuO₄. For thin films, the amount of remnant O_ap atoms is difficult to evaluate but we propose that one good measure for this may be the c-axis lattice constant, which tells us whether the reduction is insufficient or excessive.     

High-temperature superconductivity in bismuth-copper oxides of the type Bi m M n Cu p O x (M=Mg,Ca, Sr,Ba, Bi)

Several oxides of the Bi _m M _n Cu _p O _x family (m=2, 3;n=2, 3, 4;p=1, 2, 3 and M=alkaline earth or Bi), possessing structures similar to the Aurivillius family of oxides, show highT _c superconductivity. Contribution No. 514 from the Solid State and Structural Chemistry Unit.     

多量子位Heisenberg XX链中的杂质纠缠

通过分析系统的杂质位与其余部分间的纠缠N_1-A以及单个正常位与其余部分间的纠缠N_L-A研究了匀强磁场作用下含杂质Heisenberg XX链的纠缠特性.研究表明三量子位时纠缠存在的临界温度依赖于杂质参数J₁和匀强磁场B.研究发现,当量子位L为奇数时,纠缠N_1-A随量子位的增加而增大,而L为偶数时则相反,并且量子位L为偶数时的纠缠大于量子位L为奇数时的纠缠;对N_L-A, 量子位L为奇数时,纠缠随杂质参数J₁的变化与L=3类似,而L为偶数时纠缠随杂质参数|J₁|的增加而增加.     

Quasi-particle structure around a single vortex in high-Tc superconductors

For analyzing the checker-board like modulation of the local density of states (LDOS) around a vortex observed in the slightly overdoped Bi₂Sr₂CaCu₂O_x, we examined the effect of pseudogap state of high-T_c superconductors to the LDOS around the vortex. We first derived the Bogoliubov-de Gennes equation for d-wave superconductivity (d-SC) in the presence of d-spin density wave (d-SDW). Using the Fourier–Bessel expansion, we solved this equation for a single vortex state, numerically. We found that the peak of the bound states around E = 0 becomes small and modulation of the LDOS is observed for larger d-SDW order parameter.     

Analysis of numerical limits in 2-D simulations of a ferromagnetic/antiferromagnetic interface using the random field Ising model

This paper explains the Random Field Ising Model simulations of a two-dimensional ferromagnetic/antiferromagnetic interface, influenced by the exchange-bias interaction. Exchange-biased shifts, coercivity fields, the number of unreversed spins as well as the numerical errors are provided. These were tested for different structure dimensions and boundary conditions in order to find limitations of the method. The algorithm developed is simple, very effective, and provides deeper insight into the nature of the exchange-bias phenomenon.     

自旋为1的三粒子Heisenberg XXX链中杂质对热纠缠的影响

采用纠缠的度量方法Negativity研究了匀强磁场下自旋为1的含杂质三粒子Heisenberg XXX链的热纠缠特性.通过计算系统的杂质位与其余部分间的两体纠缠N_1-23及正常位与其余部分间的两体纠缠N_12-3,发现纠缠存在的临界温度T_c的改变来自杂质参数J₁的变化,随杂质参数J₁的增加而增加,外界磁场B< 关键词： 热纠缠 XXX链')" href="#">Heisenberg XXX链 杂质     

Ab initio study on magnetoelectric and electronic properties in Pb2TiVO6

First principles calculations within the projected augmented-wave (PAW) method, using the local spin density approximation plus U (LSDA+U) scheme, show that the tetragonal Pb2TiVO6 is a potential multiferroic material with antiferromagnetic (AFM) spin configuration. It has a magnetic moment of 1 μB in a one unit cell originating from the non-bonding orbital dxy in a majority spin channel and a band gap of 1.45 eV with proper U. The large BEC (Born effective charge) of Pb and Ti shows that the stereochemical activity of Pb and Ti may provide the possibility of switchable paths for the ferroelectricity in this hypothetical material. The insulating property and the lower resistivity in the recent prepared PbVO3 can be significantly improved by adopting the Ti.     

Control of the shape and duration of a laser pulse in the case of nonlinear total internal reflection

A nonlinear device based on nonlinear total internal reflection is suggested which provides a more than ten-fold shortening of the laser pulse and smooth variation of the pulse duration due to double reflection from the interface between transparent and absorbing media. Results are presented for the shape and duration of the pulse components that have been reflected and transmitted by the interface. B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., 220072, Minsk, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 325–328, May–June, 1997.     

Relationship between the diffusion rate constant and rate constant of triplet-triplet annihilation for porphyrins in liquid solutions

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70. F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 63, No. 4, pp. 613–621, July–August, 1996.