TUNNELING INVESTIGATION OF ENERGY-GAP ANISOTROPY IN SUPERCONDUCTING BULK PB
TUNNELING INVESTIGATION OF ENERGY-GAP ANISOTROPY IN SUPERCONDUCTING BULK PB
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DOI：
10.1103/physrev.186.397
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发表时间：
1969-01-01
期刊：
影响因子：
--
通讯作者：
MARCH, RH
中科院分区：
文献类型：
--
作者：
BLACKFORD, BL;MARCH, RH
发展了一种用高真空熔炼工艺将铅薄膜隧穿成铅单晶的技术。对能隙各向异性进行了初步研究。数据来自十个不同的结，包括(001)和(111)晶面上的数据。在所有情况下，两个能隙Δ1和Δ2(Δ1和lt；Δ2)在特征上是明显的，彼此相差10-15%。在所研究的隧道方向上，Δ1的最大变化是5%，而Δ2的变化要小得多。2Δ2(0)的最大观测值为2.78±0.0 1 meV，2Δ1(0)的最小观测值为2.36±0.0 1 meV。并与已发表的能隙各向异性理论进行了比较。在某些方面，该协议相当不错，而在其他方面则很差。由于k空间中能隙表面的临界点，没有发现预测结构的证据。二阶导数测量(d2VdI2对V)显示与横向声子模相关的结构群中有一个额外的峰(与薄膜Pb结的结果相比)。
A technique has been developed for tunneling from thin Pb films into Pb single crystals formed by a high-vacuum melting process. A preliminary investigation of the energy-gap anisotropy has been carried out. Data are presented from ten separate junctions, including ones on the (001) and (111) crystal facets. In all cases, two energy gaps, Δ 1 and Δ 2 (Δ 1< Δ 2), were apparent in the characteristics and differed from each other by 10-15%. The maximum variation of Δ 1 was 5% over the tunneling directions studied, while Δ 2 varied by considerably less than this. The maximum observed value of 2 Δ 2 (0) was 2.78±0.01 meV and the minimum value of 2 Δ 1 (0) was 2.36±0.01 meV. A comparison was made with a published theory of the energy-gap anisotropy. In some respects the agreement is fairly good, while in other respects it is poor. No evidence was found for the predicted structure due to critical points of the energy-gap surface in k space. Second-derivative measurements (d 2 V d I 2 versus V) showed an extra (compared to results from thin-film Pb junctions) peak in the group of structures associated with the transverse phonon modes.