Bi2212晶须中磁通线运动临界电流的反常现象

我们对同一Ｂｉ２２１２晶须样品加不同方向的磁场,比较了Ｈ∥ｂ和Ｈ∥ｃ两种情况下的Ｉ－Ｖ曲线。我们发现,当Ｈ∥ｃ时,驱动磁通线运动的临界电流Ｉｃ与温度的关系遵循一般的单调地随温度上升而下降的关系。但是,当Ｈ∥ｂ时,Ｉｃ在Ｔ＾＊＝２５．５Ｋ附近出现了一个峰值：当Ｔ〉Ｔ＾＊时,Ｉｃ温度的下降而升高;Ｔ〈Ｔ＾＊时,Ｉｃ随温度的下降而下降。我们在文章中对此现象进行了讨论。     

磁场对重电子金属CeCu6-xNix低温电阻的影响

测量了重电子金属CeCu6-xNix（x=0,0.5,0.1)，在1.8k-300k温度范围的电阻及磁场对电阻的影响（H=0,5T,10T),实验表明样品电阻的极大值对应的温度Tmax随着掺Ni含量的增大向温度降低的方向移动,而加磁场后Tmax随磁场的增加向高温方向移动,中从Kondo相互作用和相干散射的角度对这一现象的物理机制进行了分析.     

无序度对Au/Pd膜热电势的影响

我们用磁控溅射的方法制备了一系列无序度不同的Au50Pd50膜。在13K－300K的温度范围内，我们对不同无序度Au50Pd50膜的电阻率、热电势作了系统的测量，发现热电势随无序度的增加而减小，其温度依赖关系与同种成份的晶态合金的热电势温度依赖关系也很不相同。本文初步分析和讨论了其物理原因。     

Observation of Weak Anti-Localization and Electron-Electron Interaction on Few-Layer 1T′-MoTe_2 Thin Films

Electronic transports of few-layer 1T'-MoTe_2 films are measured at temperatures down to 0.26 K. The lowtemperature conductivity exhibits logarithmic temperature dependence and negative magneto response. The negative magnetoconductivity can be well fitted by the two-dimensional weak anti-localization theory taking a single channel of electrons into account, with the parameters α≈-0.5 and l_φ∝ T~(-0 5). The logarithmic temperature dependence has a positive slope κ≈0.75, indicating the dominance of electron-electron interaction over the weak anti-localization effect, with an apparently negative Coulomb screening factor F that demands future work for clarification.     

Transport Studies on GaAs/AlGaAs Two-Dimensional Electron Systems Modulated by Triangular Array of Antidots

Triangular antidot lattices of various periods and aspect ratios are fabricated on high mobility GaAs/AlGaAs two-dimensional electron systems(2DESs),and are characterized by magneto-transport measurements at low temperatures down to 300 mK. Commensurability peaks are generally observed in the magneto-resistivity ρ_(xx),and remarkable similarity between dρ_(xy)/dB and ρ_(xx) is found. In samples of relatively large aspect ratio d/a, the Aharonov-Bohm-type oscillations are clearly observed in both ρ_(xx) and ρ_(xy), as well as the quenching of the Hall resistivity ρ_(xy) in the vicinity of B = 0. These observations evince the good quality of our samples, and attest to the adequate preparation for fabricating antidot lattices of a reduced period to realize artificial graphene from GaAs/AlGaAs 2DESs.     

重电子金属CeCu5.8 M0.2(M=Ni,Zn,Cd) 低温物性的比较

研究了不同元素等量掺杂下重电子金属CeCu5.8M0.2(M=Ni,Zn,Cd)低温电阻、比热容和磁化率随温度的变化关系.分析讨论了掺杂元素M(M=Ni,Zn,Cd)的磁性、价态及原子尺寸对近藤温度Tk、相干温度(即电阻极大值的温度TRmax)、每个Ce离子在较高温度时的平均磁矩μB以及在温度降低时被传导电子自旋屏蔽过程的影响.     

Compositional Dependence of Electronic Specific Heat in AlCuCo Decagonal Quasicrystals： Evidence for the Hume-Rothery Mechanism of Phase Formation

There is no consensus whether the electron density of states of decagonal quasicrystals has a pseudogap at the Fermi energy similar to that of the icosahedron phase. We answer this question by measuring the electronic specific heat coefficient of AlCuCo decagonal single-quasicrystals over a wide range of composition. While the average valence electron number per atom, e/a, for all the resultant samples changes only within 1.5%, from-1.92 to less than 1.95. The specific heat coefficient decreases by 15% with the increasing e/a. The large change and the negative slope give strong evidence for Hume-Rothery mechanism of the decagonal phase.     

Spatially resolved gap closing in single Josephson junctions constructed on Bi_2Te_3 surface

Full gap closing is a prerequisite for hosting Majorana zero modes in Josephson junctions on the surface of topological insulators.Previously,we have observed direct experimental evidence of gap closing in Josephson junctions constructed on Bi_2Te_3 surface.In this paper we report further investigations on the position dependence of gap closing as a function of magnetic flux in single Josephson junctions constructed on Bi_2Te_3 surface.     

顶端加载、温度范围在300～1.4K的多功能交流测量恒温器

本文介绍了一台用于交流小讯号测量的低温恒温器.利用内液池减压,最低温度可达1.370K,并且在测量功率为0.15mW时,内液池液氦可以维持样品温度在1.4K达20小时以上.系统装置了在8T的背景磁场内最高可达0.18T的交变调制场,从而可以实现利用双交流法精细测量磁阻或霍耳系数随磁场变化的函数关系.试验结果表明,此恒温器具有低液氦蒸发量和可从1.3～300K连续控温的特点.用此装置对Co膜的霍尔系数测量的实验中,霍尔电压变化量的测量精度达到了0.5nV.     

块体金属玻璃Zr46.75Ti8.25Cu7.5Ni10Be27.5的超导与负电阻温度系数

测量了块体金属玻璃Zr46.75Ti8.25Cu7.5Ni10Be27.5在退火前后其电阻值随温度的变化,测量的温度范围为1.5-300K.样品在退火前后都发现有超导现象.零磁场下其超导转变温度Tc分别为1.84和3.76K.在5-300K温度范围内,原始样品具有负的电阻温度系数.如果取Zr,Ti,Cu,Ni及Be分别贡献出1.5,1.5,0.5,0.5及两个传导电子,则可以用扩展的Faber-Ziman理论去解释原始样品的负电阻温度系数.还对块体金属玻璃Zr46.75Ti8.25Cu7.5Ni10Be27.5在温度范围5-300K之间的R(T)曲线用一个多项式进行了拟合.