TY - JOUR
T1 - Rare-region onset of superconductivity in niobium nanoislands
AU - Durkin, Malcolm
AU - Garrido-Menacho, Rita
AU - Gopalakrishnan, Sarang
AU - Jaggi, Narendra K.
AU - Kwon, Ji Hwan
AU - Zuo, Jian Min
AU - Mason, Nadya
N1 - Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/1/10
Y1 - 2020/1/10
N2 - We report measurements of the superconducting properties of isolated Nb nanoislands (600-2500 nm diameters) and explain their unusual behavior in terms of rare-region onset effects, predicted for random metal-superconductor granular systems [B. Spivak, P. Oreto, and S. A. Kivelson, Phys. Rev. B 77, 214523 (2008)10.1103/PhysRevB.77.214523]. We find that the island Tc is strongly suppressed even at large island diameters, exceeding 1 μm. This behavior is unexpected given that conventional theories of superconductivity in small grains predict suppression of Tc only at a length scale that is two orders of magnitude smaller. In addition, we observe large island-to-island variations in Tc for nominally identical islands. These two experimental observations, coupled with direct measurement of grain distribution using transmission electron microscopy, conductive atomic force microscopy, and computer simulations, provide evidence for our picture in which the onset of superconductivity on an island coincides with the transition temperature of its largest constituent grain, and then spreads to other grains due to proximity coupling.
AB - We report measurements of the superconducting properties of isolated Nb nanoislands (600-2500 nm diameters) and explain their unusual behavior in terms of rare-region onset effects, predicted for random metal-superconductor granular systems [B. Spivak, P. Oreto, and S. A. Kivelson, Phys. Rev. B 77, 214523 (2008)10.1103/PhysRevB.77.214523]. We find that the island Tc is strongly suppressed even at large island diameters, exceeding 1 μm. This behavior is unexpected given that conventional theories of superconductivity in small grains predict suppression of Tc only at a length scale that is two orders of magnitude smaller. In addition, we observe large island-to-island variations in Tc for nominally identical islands. These two experimental observations, coupled with direct measurement of grain distribution using transmission electron microscopy, conductive atomic force microscopy, and computer simulations, provide evidence for our picture in which the onset of superconductivity on an island coincides with the transition temperature of its largest constituent grain, and then spreads to other grains due to proximity coupling.
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U2 - 10.1103/PhysRevB.101.035409
DO - 10.1103/PhysRevB.101.035409
M3 - Article
AN - SCOPUS:85078444961
SN - 2469-9950
VL - 101
JO - Physical Review B
JF - Physical Review B
IS - 3
M1 - 035409
ER -