Abstract
In our tunneling investigation using Andreev superconductor-normal metal-superconductor contacts on LiFeAs single crystals we observed two reproducible independent subharmonic gap structures at dynamic conductance characteristics. From these results, we can derive the energy of the large superconducting gap ΔL = (2.5–3.4) meV and the small gap ΔS = (0.9–1) meV at T = 4.2 K for the T localC ≈ (10.5–14) K (the contact area critical temperature which deviation causes the variation of ΔL). The BCS-ratio is found to be 2ΔL/k B T C = 4.6–5.6, whereas 2ΔS/k B T C ≪ 3.52 results from induced superconductivity in the bands with the small gap.
Similar content being viewed by others
References
Y. Kamihara, H. Hiramatsu, M. Hirano, et al., J. Am. Chem. Soc. 128, 10012 (2006); J. Am. Chem. Soc. 130, 3296 (2008).
X. C. Wang, Q. Q. Liu, Y. X. Lv, et al., Solid State Commun. 148, 538 (2008); J. H. Tapp, Z. Tang, B. Lv, et al., Phys. Rev. B 78, 060505(R) (2008).
S. V. Borisenko, V. B. Zabolotnyy, D. V. Evtushinsky, et al., Phys. Rev. Lett. 105, 067002 (2010).
O. Heyer, T. Lorenz, V. B. Zabolotnyy, et al., Phys. Rev. B 84, 064512 (2011).
D. J. Singh and M.-H. Du, Phys. Rev. Lett. 100, 237003 (2008); D. J. Singh, Physica C 469, 418 (2009).
I. A. Nekrasov, Z. V. Pchelkina, and M. V. Sadovskii, JETP Lett. 88, 144 (2008).
A. I. Coldea, J. D. Fletcher, A. Carrington, et al., Phys. Rev. Lett. 101, 216402 (2008).
S. Raghu, X.-L. Qi, C.-X. Liu, et al., Phys. Rev. B 77, 220503(R) (2008).
J. Li and Y.-P. Wang, Chin. Phys. Lett. 25, 2232 (2008).
E. Z. Kurmaev, J. A. McLeod, N. A. Skorikov, et al., J. Phys.: Condens. Matter 21, 345701 (2009).
T. Miyake, K. Nakamura, R. Arita, and M. Imada, J. Phys. Soc. Jpn. 79, 044705 (2010).
C. Platt, R. Thomale, and W. Hanke, Phys. Rev. B 84, 235121 (2011).
R. A. Jishi and H. M. Alyahyaei, Adv. Cond. Mat. Phys. 2010, 804343 (2010).
I. A. Nekrasov, Z. V. Pchelkina, and M. V. Sadovskii, JETP Lett. 88, 543 (2008).
E. Z. Kuchinskii, I. A. Nekrasov, and M. V. Sadovskii, JETP Lett. 91, 518 (2010).
R. H. Liu, T. Wu, G. Wu, et al., Nature 459, 64 (2009).
J. Bardeen, L. N. Cooper, and J. R. Schrieffer, Phys. Rev. 108, 1175 (1957).
L. Boeri, O. V. Dolgov, and A. A. Golubov, Physica C 469, 628 (2009).
A. A. Abrikosov, Physica C 317-318, 154 (1999).
A. A. Kordyuk, V. B. Zabolotnyy, D. V. Evtushinsky, et al., Phys. Rev. B 83, 134513 (2011).
I. Morozov, A. Boltalin, O. Volkova, et al., Cryst. Growth Design 10, 4428 (2010).
J. Moreland and J. W. Ekin, J. Appl. Phys. 58, 3888 (1985).
J. Müller, J. M. van Ruitenbeek, and L. J. de Jongh, Physica C 191, 485 (1992).
Ya. G. Ponomarev, S. A. Kuzmichev, M. G. Mikheev, et al., Phys. Rev. B 79, 224517 (2009).
Ya. G. Ponomarev and A. V. Rakhmanina, Prib. Tekh. Eksp. 5, 120 (1970).
I. R. Shein and A. L. Ivanovskii, JETP Lett. 88, 329 (2008).
U. Stockert, M. Abdel-Hafiez, D. V. Evtushinsky, et al., Phys. Rev. B 83, 224512 (2011).
D. S. Inosov, J. S. White, D. V. Evtushinsky, et al., Phys. Rev. Lett. 104, 187001 (2010).
A. F. Andreev, Sov. Phys. JETP 19, 1228 (1964).
R. Kümmel, U. Gunsenheimer, and R. Nicolsky, Phys. Rev. B 42, 3992 (1990).
Yu. V. Sharvin, Sov. Phys. JETP 21, 655 (1965).
B. A. Aminov, A. A. Golubov, and M. Yu. Kupriyanov, Phys. Rev. B 53, 365 (1996).
Ya. G. Ponomarev, S. A. Kuzmichev, M. G. Mikheev, et al., Solid State Commun. 129, 85 (2004).
Ya. G. Ponomarev, S. A. Kuzmichev, N. M. Kadomtseva, et al., JETP Lett. 79, 484 (2004).
S. A. Kuzmichev, T. E. Shanygina, S. N. Tchesnokov, and S. I. Krasnosvobodtsev, Solid State Commun. 152, 119 (2012).
T. E. Shanygina, Ya. G. Ponomarev, S. A. Kuzmichev, et al., JETP Lett. 93, 94 (2011).
V. M. Pudalov, O. E. Omel’yanovskii, E. P. Khlybov, et al., Phys. Usp. 54, 648 (2011).
T. E. Shanygina, Ya. G. Ponomarev, S. A. Kuzmichev, et al., J. Phys.: Conf. Ser. (2012, in press).
Ya. G. Ponomarev, S. A. Kuzmichev, M. G. Mikheev, et al., JETP 140, 527 (2011).
H. Nakamura, M. Machida, T. Koyama, and N. Hamada, Phys. Soc. Jpn. 78, 123712 (2009).
T. Matsui, H. Ohta, and R. Hayashi, Jpn. J. Appl. Phys. 25, L671 (1986).
Ya. G. Ponomarev, K. K. Uk, M. A. Lorentz, et al., Inst. Phys. Conf. Ser. 167, 241 (2000).
E. Heumen, J. Vuorinen, K. Koepernik, et al., Phys. Rev. Lett. 106, 027002 (2011).
V. A. Moskalenko, Phys. Met. Metall. 4, 503 (1959).
H. Suhl, B. T. Matthias, L. R. Walker, et al., Phys. Rev. Lett. 12, 552 (1959).
F. Wei, F. Chen, K. Sasmal, et al., Phys. Rev. B 81, 134527 (2010).
Y. J. Song, J. S. Ghim, J. H. Yoon, et al., Europhys. Lett. 94, 57008 (2011).
H. Kim, M. A. Tanatar, Y. J. Song, et al., Phys. Rev. B 83, 100502(R) (2011).
Y. Imai, H. Takahashi, K. Kitagawa, et al., J. Phys. Soc. Jpn. 80, 013704 (2011).
K. Sasmal, B. Lv, Z. Tang, et al., Phys. Rev. B 81, 144512 (2010).
I. K. Yanson, V. V. Fisun, N. L. Bobrov, et al., Phys. Rev. B 67, 024517 (2003).
Author information
Authors and Affiliations
Corresponding author
Additional information
The article is published in the original.
Rights and permissions
About this article
Cite this article
Kuzmichev, S.A., Shanygina, T.E., Morozov, I.V. et al. Investigation of LiFeAs by means of “break-junction” technique. Jetp Lett. 95, 537–543 (2012). https://doi.org/10.1134/S0021364012100086
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1134/S0021364012100086