Abstract
We have analyzed about a hundred voltage-dependent differential resistance dV/dI(V) curves of metallic point contacts between c-axis-oriented MgB2 thin film and Ag, which exhibit clear Andreev reflection features connected with the superconducting gap. About one half of the curves show the presence of a second larger gap. The histogram of the double gap distribution reveals distinct maxima at 2.4 and 7 meV, while curves with single-gap features result in a more broad maximum at 3.5 meV. The double-gap distribution is in qualitative agreement with the distribution of gap values over the Fermi surface calculated by H. J. Choi et al. (cond-mat/0111183). The data unequivocally show the presence of two gaps: ΔS=2.45±0.15 meV and ΔL=7.0±0.45 meV in MgB2 with the gap ratio ΔL/ΔS=2.85±0.15. Our observations further prove a widely discussed multigap scenario for MgB2, where two distinct gaps are seen in the clean limit, while a single averaged gap is present in the dirty one.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
J. Nagamatsu, N. Nakagawa, T. Muranaka, et al., Nature 410, 63 (2001).
G. Karapetrov, M. Javarone, W. K. Kwok, et al., Phys. Rev. Lett. 86, 4374 (2001).
G. Rubio-Bollinger, H. Suderow, and S. Vieira, Phys. Rev. Lett. 86, 5582 (2001).
A. Sharoni, I. Felner, and D. Millo, Phys. Rev. B 63, 220508(R) (2001).
P. Seneor, C.-T. Chen, N.-C. Yeh, et al., Phys. Rev. B 65, 012505 (2002).
F. Giubileo, D. Roditchev, W. Sachs, et al., cond-mat/0105146.
F. Giubileo, D. Roditchev, W. Sachs, et al., Phys. Rev. Lett. 87, 177008 (2001).
M. H. Badr, M. Freamat, Y. Sushko, and K.-W. Ng, cond-mat/0110421.
Y. Zhang, D. Kinion, J. Chen, et al., cond-mat/0107478.
H. Schmidt, J. F. Zasadzinski, K. E. Gray, et al., Phys. Rev. B 63, 220504R (2001).
A. Kohen and G. Deutscher, Phys. Rev. B 64, 060506(R) (2001).
A. Plecenik, Š. Beňačka, P. Kúš, et al., Physica C 368, 251 (2002).
F. Laube, G. Goll, J. Hagel, et al., Europhys. Lett. 56, 296 (2001).
R. S. Gonnelli, A. Calzolari, D. Daghero, et al., cond-mat/0107239.
P. Szabó, P. Samuely, J. Kacmarćik, et al., Phys. Rev. Lett. 87, 137005 (2001).
Y. Bugoslavsky, Y. Miyoshi, G. K. Perkins, et al., cond-mat/0110296.
N. L. Bobrov, P. N. Chubov, Yu. G. Naidyuk, et al., cond-mat/0110006.
C. Buzea and T. Yamashita, Supercond. Sci. Technol. 14(11), R115 (2001).
A. Y. Liu, I. I. Mazin, and J. Kortus, Phys. Rev. Lett. 87, 087005 (2001).
J. Kortus, I. I. Mazin, K. D. Belashchenko, et al., Phys. Rev. Lett. 86, 4656 (2001).
W. N. Kang, Hyeong-Jin Kim, Eun-Mi Choi, et al., Phys. Rev. Lett. 87, 087002 (2001).
A. Wexler, Proc. Phys. Soc., London 89, 927 (1966).
P. C. Canfield, D. K. Finnemore, S. L. Bud’ko, et al., Phys. Rev. Lett. 86, 2423 (2001).
G. E. Blonder, M. Tinkham, and T. M. Klapwijk, Phys. Rev. B 25, 4515 (1982).
R. C. Dynes, V. Narayanamurti, and J. P. Garno, Phys. Rev. Lett. 41, 1509 (1978).
Hyoung Joon Choi, David Roundy, Hong Sun, et al., cond-mat/0111183.
D. K. Finnemore, J. E. Ostenson, S. L. Bud’ko, et al., Phys. Rev. Lett. 86, 2420 (2001).
A. Brinkman, A. A. Golubov, H. Rogalla, et al., cond-mat/0111115.
V. D. P. Servedio, S.-L. Drechsler, and T. Mishonov, cond-mat/0111434.
Author information
Authors and Affiliations
Additional information
From Pis’ma v Zhurnal Éksperimental’no\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} \) i Teoretichesko\(\overset{\lower0.5em\hbox{$\smash{\scriptscriptstyle\smile}$}}{l} \) Fiziki, Vol. 75, No. 5, 2002, pp. 283–286.
Original English Text Copyright © 2002 by Naidyuk,Yanson, Tyutrina, Bobrov, Chubov, Kang, Hyeong-Jin Kim, Eun-Mi Choi, Sung-Ik Lee.
This article was submitted by the authors in English.
Rights and permissions
About this article
Cite this article
Naidyuk, Y.G., Yanson, I.K., Tyutrina, L.V. et al. Superconducting energy gap distribution in c-axis oriented MgB2 thin film from point contact study. Jetp Lett. 75, 238–241 (2002). https://doi.org/10.1134/1.1478521
Received:
Issue Date:
DOI: https://doi.org/10.1134/1.1478521