ENERGY GAP MEASUREMENTS BY TUNNELING BETWEEN SUPERCONDUCTING FILMS. II. MAGNETIC FIELD DEPENDENCE
ENERGY GAP MEASUREMENTS BY TUNNELING BETWEEN SUPERCONDUCTING FILMS. II. MAGNETIC FIELD DEPENDENCE
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通过超导薄膜之间的隧道测量能隙。
DOI：
10.1103/physrev.135.a24
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发表时间：
1964
期刊：
影响因子：
--
通讯作者：
D. Douglass
中科院分区：
文献类型：
--
作者：
R. Meservey;D. Douglass
用电子隧穿技术测量了8种铝膜（厚度d为420 ~ 9850 μ m）在Tc ≥ T≥ 0.7Tc的温度区间内的能隙2 Δ随磁场的变化关系.约化能隙与约化场的测量可以表示为具有单个参数d λ的曲线族。当d λ> 1时，[Δ（O，T）] 2与[HHC] 2的关系曲线有一个小的负曲率，然后在HHC处突然下降.对于d λ< 1，曲率总是正的，随着场的增加而减小。对于d λ <$1，我们得到一条几乎直线。当d λ≥ 1时，结果与Ginzburg-Landau（GL）方程的预言定性一致，但当d λ< 1时，结果与GL方程的预言不一致。有人建议，这种差异与GL方程的解决方案可能会出现故障的假设，序参数是独立的位置。对厚度为1000 μ m的铅膜在TTc = 0.14时的测量表明，随着H接近Hc，能隙平滑地以正曲率趋于零.
The magnetic field dependence of the energy gap 2 Δ was measured by the electron tunneling technique over the temperature interval T c≥ T≥ 0.7 T c on eight aluminum films ranging in thickness d from 420 to 9850 Å. Measurements of the reduced energy gap versus the reduced field can be represented as a family of curves with a single parameter d λ. For d λ> 1 the [Δ (O, T)] 2 versus [H H c] 2 curves have an initial small negative curvature and then drop abruptly at H c. For d λ< 1 the curvature is always positive, decreasing in magnitude as the field increases. For d λ≈ 1 we obtain an almost straight line. The results are qualitatively as predicted by the Ginzburg-Landau (GL) equations for d λ≥ 1 but not for d λ< 1. It is suggested that this discrepancy with solutions of the GL equations may arise from the breakdown of the assumption that the order parameter is independent of position. Measurements on a lead film of thickness 1000 Å at T T c= 0.14 showed that the energy gap goes smoothly to zero with positive curvature as H approaches H c.