Antiresonance Effect in Electronic Tunnelling through a One-Dimensional Quantum Dot Chain

Electronic tunnelling through a one-dimensional quantum dot chain is theoretically studied, when two leads couple to the individual component quantum dots of the chain arbitrarily. If there are some dangling quantum dots in the chain outside the leads, the electron tunnelling through the quantum dot chain is wholly forbidden while the energy of the incident electron is just equal to the molecular energy levels of the dangling quantum dots, which is known as the antiresonance effect. In addition, the influence of electron interaction on the antiresonance effect is discussed within the Hartree-Fock approximation.     

NiMnCo-C-S系中掺硫金刚石单晶的研究

本文在5.5～5.7 GPa,1450～1550℃的条件下由镍锰钴-石墨-硫体系中合成金刚石单晶.合成的金刚石晶体具有完整的{111}和{100}面,内部有少量包裹体.晶体表面有凹坑,凹坑内有许多细小的孔洞,且有连晶出现.X射线荧光光谱检测结果表明,随着反应体系中硫含量的增加,晶体中硫和锰的含量明显增加,而镍和钴的含量却降低.这由于硫与触媒中的锰发生了反应,改变了合成触媒的成分配比,进而改变了触媒的性质.     

The hysteresis loops of a ferroelectric bilayer film with surface transition layers

Based on the transverse Ising model in the framework of the mean field approximation,this paper discusses a ferroelectric bilayer film with the surface transition layers within each constituent slab and an antiferroelectric interfacial coupling between two slabs.The hysteresis loop of a bilayer film is investigated.The results show that the surface transition layer in a ferroelectric bilayer film plays a significant role in realizing the multiple-state memory.     

α粒子散射实验与原子核的发现——"最美丽"的十大物理实验之三

1实验背景 自1897年汤姆孙(J.J.Thomson 1856～1940年)从实验中发现电子;1896年亨利·贝克勒(H.A.Becquere1 1852～1908年)发现铀的放射性现象;1898年居里夫人(M.Curie 1867～1934年)发现镭的放射性现象;1897年卢瑟福(E.Rutherford 1871～1937年,英藉新西兰人)发现放射性中的α射线和β射线;1900年维拉德(P.U.Villard 1860～1934年)发现放射性中第三种射线--γ射线以后,使人们认识到原子是可分的,原子是有结构的.因此,各国物理学家们便开始探索原子的复杂结构.     

Combined effect of the transition layer and interfacial coupling on the properties of ferroelectric bilayer film

Within the framework of modified Ginzburg--Landau--Devonshire phenomenological theory, a ferroelectric bilayer film with a transition layer within each constituent film and an interfacial coupling between two materials has been studied. Properties including the Curie temperature and the spontaneous polarization of a bilayer film composed of two equally thick ferroelectric constituent films are discussed. The results show that the combined effect of the transition layer and the interfacial coupling plays an important role in explaining the interesting behaviour of ferroelectric multilayer structures consisting of two ferroelectric materials.     

160Tb β-衰变纲图研究

对由160Tb的β-衰变而产生的γ射线利用GeLi和HpGe探测器进行了单谱和γ γ符合谱的测量.根据单谱和γ-γ符合谱的测量结果给出了160Tb的β-衰变纲图.并用绝热对称转动模型对160Dy中转动带与振动带的耦合参数Zγ值进行了计算,得出从振动带到转动带的γ跃迁几率B(E2)值之比不能通过唯一的Zγ值来描述.Tb/β-衰变;衰变纲图;带耦合参数 The γtransitions in 160Tb decay has been studied by γ ray spectroscopy and γ γ coincidence measurements with high efficiency Ge(Li) and HpGe detectors. The β- decay scheme of 160Tb was proposed according to the results of γ ray spectroscopy and γ γ coincidence measurement. The band mixing parameter Zγ for 160Dy is determined and it is observed that the measured γ ray branching ratios do not lead to a unique value of Zγ for 160 Dy.     

160Tb β-衰变纲图研究

对由160Tb的β-衰变而产生的γ射线利用GeLi和HpGe探测器进行了单谱和γ-γ符合谱的测量. 根据单谱和γ-γ符合谱的测量结果给出了160Tb的β-衰变纲图. 并用绝热对称转动模型对160Dy 中转动带与振动带的耦合参数Zγ值进行了计算,得出从振动带到转动带的γ跃迁几率B(E2)值之比不能通过唯一的Zγ值来描述.     

Influence of Surface Transition Layers on Phase Transformation and Pyroelectric Properties of Ferroelectric Thin Film

Taking into account surface transition layers （STLs）, we study the phase transformation and pyroelectric properties of ferroelectric thin films by employing the transverse Ising model （TIM） in the framework of the mean field approximation. The distribution functions representing the intra-layer and inter-layer couplings between the two nearest neighbour pseudo-spins are introduced to characterize STLs. Compared with the results obtained by the traditional treatments for the thin films using only the single surface transition layer （SSL）, it is shown that the STL model reflects a more realistic and comprehensive situation of films. The effects of various parameters on the phase transformation properties have shown that STL can make the Curie temperature of the film higher or lower than that of the corresponding Sulk material, and the thickness of STL is a key factor influencing the film properties. For a film with definite thickness, there exists a critical STL thickness at which ferroelectricity will disappear when the intra-layer and inter-layer interactions are weak.