共查询到19条相似文献,搜索用时 234 毫秒
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拓扑绝缘体的出现为寻找拓扑超导体和Majorana费米子提供了一种可能的途径. 在拓扑绝缘体Bi2Te3表面沉积极薄的不连续铅膜, 试图通过邻近效应感应出大片的超导区, 为下一步研究拓扑超导电性创造条件.借助四引线电输运测量实验, 在0.25 K的低温下看到了超流现象, 表明沉积在Bi2Te3表面的厚度小于20 nm的颗粒化铅膜能够诱导邻近效应, 并且使大片Bi2Te3超导.
关键词:
超导邻近效应
S-N-S结
拓扑绝缘体 相似文献
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采用磁控溅射,紫外线光刻和离子束刻蚀制备了La2/3Ca1/3MnO3/Eu2CuO4/La2/3Ca1/3MnO3磁性隧道结.通过对获得的磁性隧道结的I-V特性测量,发现非线性的I-V特性,显示结样品的隧穿特性.有趣的是发现在电极材料La2/3Ca1/3MnO3的金属-绝缘体转变温度(Tp)以下,I-V曲线出现一个跳变.随着温度降低,开始出现跳变的临界电流增大,但是跳变都发生在同样的电压下~209mV.当电流增大或减小在跳变点附近出现回滞.这一跳变只发生在铁磁金属态,表明这是一个磁性相关联的效应,可能对应一种新的磁性开关过程.虽然,目前对这一现象背后的物理机理还不清楚,但是,这一现象有可能在未来自旋电子学器件方面具有潜在的应用价值.
关键词:
庞磁电阻
磁性隧道结
开关效应 相似文献
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基于拓扑绝缘体材料的约瑟夫森结是寻找马约拉纳零能模的候选器件,因而受到拓扑量子计算研究领域的关注.这方面实验的关键之一,是制备具有优质结区的约瑟夫森器件.本工作在三维拓扑绝缘体Bi2Te3和Bi2(SexTe1-x)3纳米线上制作了约瑟夫森结器件,研究了其结区的超导邻近效应、多重安德列夫反射和超流-相位关系,观测到了约瑟夫森结的临界超流随磁场增大而反常地增大、其交流约瑟夫森效应出现半整数的夏皮洛台阶的实验结果.本文还讨论了这些反常现象的可能来源,特别是与结区界面处超导电极的Ti缓冲层和拓扑绝缘体纳米线中的Te元素形成TiTe铁磁性合金层的关系. 相似文献
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单层FeSe/SrTiO3界面增强超导的发现为理解高温超导机理提供了一个新的途径,也为实现新的高温超导体开拓了新思路.本文通过在SrTiO3(001)表面高温沉积Mg进而沉积单层FeSe薄膜,制备出了FeSe/MgO双层/SrTiO3异质结.利用扫描隧道显微镜研究了异质结的电学及超导特性,观测到约14–15 meV的超导能隙,比体相FeSe超导能隙值增大了5–6倍,与K掺杂双层FeSe/SrTiO3的超导能隙值相当.这一结果可理解为能带弯曲造成的界面电荷转移和界面处电声耦合共同作用导致的超导增强.FeSe/MgO界面是继FeSe/TiO2之后的一个新界面超导体系,为研究界面高温超导机理提供了新载体. 相似文献
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本文讨论了单结 SQUID 的磁通响应时间,得到了平衡态时全磁通的分布,并由此得到了热涨落使准静态磁通响应曲线不同于无噪声时的情形.热涨落可以使无迴滞单结 SQUID 的临界电流下降,电流-位相关系畸变,也可以使有迥滞单结 SQUID 的迴滞消失.最后我们讨论了相应的 RF-SQUID 的特性曲线. 相似文献
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制备了Au-SiO2-Si结构MIS隧道发光结.测试并分析了该结的发光特性及电流-电压(I-V)特性.指出结的发光是由各膜层界面激发的表面等离极化激元(Surface Plasmon Polariton.SPP)与膜层表面粗糙度相互耦合的结果.观察到MIS结I-V特性中存在的负阻现象,采用SPP对电子的束缚模型对这一现象进行了初步分析.利用原子力显微镜(AFM)对结的表面形貌进行了观测,由此讨论了MIS隧道结的发光与电子在结内的隧穿输运特性之间的内在关系.
关键词: 相似文献
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The effect of superconducting fluctuations on quasi-particle current of tunneling junction is discussed. The anomalous contribution in tunneling current from interacting across the barrier fluctuations is found. It gives rise to pseudogap minimum in Rd(V). Similar dependence is observed experimentally in NbN-I-Pb junctions. Reasons are given to suggest that there is some ultrathin layer on the surface of NbN films whose properties drastically differ from the bulk one. 相似文献
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I. A. Devyatov M. Yu. Kupriyanov 《Journal of Experimental and Theoretical Physics》1998,87(2):375-381
Elastic resonant tunneling through a single localized state in an insulating layer (I-layer) situated in the constriction
zone between two thick superconducting electrodes is investigated theoretically, and the current-voltage characteristic (IVC)
of the structure is calculated. The accompanying analysis leads to the prediction that an appreciable current can flow through
the structure, not at |eV|=2Δ (Δ is the modulus of the order parameter of the superconducting electrodes) as in the case of an ordinary SIS junction,
but at |eV|⩾Δ, and also that the IVC can acquire segments of negative differential resistance in the case of tunneling through a single
localized state. Averaging of the IVC over an ensemble of localized states distributed uniformly throughout the volume of
the I-layer and with respect to the energy near the chemical potential min the limit Γ0/Δ≫1 (Γ0 is the half-width of the resonance line of the localized state) produces a smaller excess current than in a junction of the
SNS type. It is shown that the IVC’s exhibit a transition from an excess current to a deficit current as Γ0 decreases in the high-voltage range.
Zh. éksp. Teor. Fiz. 114, 687–699 (August 1998) 相似文献
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Focused ion beam (FIB) and ion milling techniques are developed for the fabrication of Bi2Sr2CaCu2O8+1d
(Bi-2212) stacked junctions with in-plane size L ab ranging from several microns down to the submicron scale without degradation of superconducting transition temperature T
c. It is found that the behavior of submicron junctions (L
ab<1 μm) is quite different from that of larger ones. The critical current density is considerably suppressed, the hysteresis
and multibranched structure of the current-voltage (I-V) characteristics are eliminated, and a periodic structure of current
peaks appears reproducibly on the I-V curves at low temperatures. The period ΔV of the structure is consistent with the Coulomb charging energy of a single pair, ΔV=e/C, where C is the effective capacitance of the stack. It is considered that this behavior originates from the Coulomb blockade of the
intrinsic Josephson tunneling in submicron Bi-2212 stacks.
Pis’ma Zh. éksp. Teor. Fiz. 69, No. 1, 75–80 (10 January 1999)
Published in English in the original Russian journal. Edited by Steve Torstveit. 相似文献
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制备了Cu-Al2O3-MgF2-Au双势垒隧道发光结,分析了结加上一定偏压后的电子隧穿过程.指出由于构成隧道结的绝缘栅薄膜的厚度及禁带宽度的不同而导致双势垒中能级产生分裂,使电子通过栅区时产生共振隧穿现象.根据这一现象,并结合结的I-V特性,对结的发光性能进行了讨论.这种结构的结与普通单势垒MIM结相比,其发光效率(10-6—10-5)提高了近一个数量级,且发光光谱的波长范围及谱峰均向短波长方向
关键词: 相似文献
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在约瑟夫森结跳变电流统计分布的理论拟合过程中,通常考虑的是宏观量子隧穿与热激活这两种过程. 对Bi2Sr2CaCu2O8+δ表面本征约瑟夫森结的结果分析表明,在宏观量子隧穿与热激活的交界区域内,若考虑量子修正能使实验曲线与理论曲线符合得更好. 这种较为完整的拟合方法,对研究本征约瑟夫森器件中的宏观量子现象及其在超导量子比特中的应用具有积极的意义.
关键词:
约瑟夫森结
跳变电流分布
量子修正 相似文献
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《Physica C: Superconductivity and its Applications》1999,311(1-2):93-97
The Josephson coupling between two identical high-temperature superconductors was studied theoretically based on a superconducting–normal (SN) bilayer model with s+id-wave pairing in the S layer. It is indicated that due to the proximity effect between S and N layers as the interlayer hopping t⊥ decreases, the product of the tunneling current through the junction and the normal-state resistance of the junction can be substantially reduced from the value described by the Ambegaokar–Baratoff (AB) theory. Our theoretical result is in good agreement with the experiments. 相似文献