Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Theory of anomalous proximity effects in phase-coherent structures
AU - Claughton, N R
AU - Hui, V C
AU - Lambert, Colin
PY - 1995
Y1 - 1995
N2 - We present theoretical results for the change δG in the electrical conductance G of a mesoscopic sample due to the switching on of superconductivity. Due to competition between normal and Andreev scattering, the sign of δG depends in detail on the impurity configuration within a device. In contrast with universal conductance fluctuations, we demonstrate that δG can scale with the system size and therefore, as well as being negative, can have a magnitude much greater than 2e2/h. For clean systems, this anomalous behavior arises from low-angle quasiparticle scattering at normal-superconducting interfaces. For dirty systems it arises from the presence of normal-state conductance resonances. We also examine the magnetic-field dependence of δG and show that fields on the scale of a flux quantum through a sample can change the sign of δG and suppress its magnitude. For a superconducting order parameter of magnitude Δ0, we present results for the Δ susceptibility χΔ=limΔ0→0∂G(Δ0)/∂Δ02. For clean systems, where the normal-state conductance is quantized in units of 2e2/h, we predict that χΔ diverges at normal-state conductance steps. For dirty systems, it is shown that χΔ is sensitive to the local environment of single impurity atoms.
AB - We present theoretical results for the change δG in the electrical conductance G of a mesoscopic sample due to the switching on of superconductivity. Due to competition between normal and Andreev scattering, the sign of δG depends in detail on the impurity configuration within a device. In contrast with universal conductance fluctuations, we demonstrate that δG can scale with the system size and therefore, as well as being negative, can have a magnitude much greater than 2e2/h. For clean systems, this anomalous behavior arises from low-angle quasiparticle scattering at normal-superconducting interfaces. For dirty systems it arises from the presence of normal-state conductance resonances. We also examine the magnetic-field dependence of δG and show that fields on the scale of a flux quantum through a sample can change the sign of δG and suppress its magnitude. For a superconducting order parameter of magnitude Δ0, we present results for the Δ susceptibility χΔ=limΔ0→0∂G(Δ0)/∂Δ02. For clean systems, where the normal-state conductance is quantized in units of 2e2/h, we predict that χΔ diverges at normal-state conductance steps. For dirty systems, it is shown that χΔ is sensitive to the local environment of single impurity atoms.
U2 - 10.1103/PhysRevB.51.11635
DO - 10.1103/PhysRevB.51.11635
M3 - Journal article
VL - 51
SP - 11635
EP - 11646
JO - Physical review B
JF - Physical review B
SN - 0163-1829
IS - 17
ER -