J. Phys. Soc. Jpn. 88, 043702 (2019) [5 Pages]

Unconventional Superconductivity in Heavy Fermion UTe2

Anne de Visser
JPSJ News Comments 16,  08 (2019).

+ Affiliations
1IMR, Tohoku University, Oarai, Ibaraki 311-1313, Japan2University Grenoble Alpes, CEA, IRIG-PHELIQS, F-38000 Grenoble, France3Graduate School of Science, Kobe University, Kobe 657-8501, Japan

We grew single crystals of the recently discovered heavy fermion superconductor UTe2, and measured the resistivity, specific heat and magnetoresistance. Superconductivity (SC) was clearly detected at Tsc = 1.65 K as sharp drop of the resistivity in a high quality sample of RRR = 35. The specific heat shows a large jump at Tsc indicating strong coupling. The large Sommerfeld coefficient, γ = 117 mJ K−2 mol−1 extrapolated in the normal state and the temperature dependence of C/T below Tsc are the signature of unconventional SC. The discrepancy in the entropy balance at Tsc between SC and normal states points out that hidden features must occur. Surprisingly, a large residual value of the Sommerfeld coefficient seems quite robust (γ0/γ ∼ 0.5). The large upper critical field Hc2 along the three principal axes favors spin-triplet SC. For Hb-axis, our experiments do not reproduce the huge upturn of Hc2 reported previously. This discrepancy may reflect that Hc2 is very sensitive to the sample quality. A new perspective in UTe2 is the proximity of a Kondo semiconducting phase predicted by the LDA band structure calculations.

©2019 The Physical Society of Japan


  • 1 D. Aoki and J. Flouquet, J. Phys. Soc. Jpn. 81, 011003 (2012). 10.1143/JPSJ.81.011003 LinkGoogle Scholar
  • 2 D. Aoki, K. Ishida, and J. Flouquet, J. Phys. Soc. Jpn. 88, 022001 (2019). 10.7566/JPSJ.88.022001 LinkGoogle Scholar
  • 3 S. S. Saxena, P. Agarwal, K. Ahilan, F. M. Grosche, R. K. W. Haselwimmer, M. J. Steiner, E. Pugh, I. R. Walker, S. R. Julian, P. Monthoux, G. G. Lonzarich, A. Huxley, I. Sheikin, D. Braithwaite, and J. Flouquet, Nature 406, 587 (2000). 10.1038/35020500 CrossrefGoogle Scholar
  • 4 D. Aoki, A. Huxley, E. Ressouche, D. Braithwaite, J. Flouquet, J.-P. Brison, E. Lhotel, and C. Paulsen, Nature 413, 613 (2001). 10.1038/35098048 CrossrefGoogle Scholar
  • 5 N. T. Huy, A. Gasparini, D. E. de Nijs, Y. Huang, J. C. P. Klaasse, T. Gortenmulder, A. de Visser, A. Hamann, T. Görlach, and H. v. Löhneysen, Phys. Rev. Lett. 99, 067006 (2007). 10.1103/PhysRevLett.99.067006 CrossrefGoogle Scholar
  • 6 F. Lévy, I. Sheikin, B. Grenier, and A. D. Huxley, Science 309, 1343 (2005). 10.1126/science.1115498 CrossrefGoogle Scholar
  • 7 D. Aoki, T. D. Matsuda, V. Taufour, E. Hassinger, G. Knebel, and J. Flouquet, J. Phys. Soc. Jpn. 78, 113709 (2009). 10.1143/JPSJ.78.113709 LinkGoogle Scholar
  • 8 E. A. Yelland, J. M. Barraclough, W. Wang, K. V. Kamenev, and A. D. Huxley, Nat. Phys. 7, 890 (2011). 10.1038/nphys2073 CrossrefGoogle Scholar
  • 9 A. Gourgout, A. Pourret, G. Knebel, D. Aoki, G. Seyfarth, and J. Flouquet, Phys. Rev. Lett. 117, 046401 (2016). 10.1103/PhysRevLett.117.046401 CrossrefGoogle Scholar
  • 10 G. Bastien, A. Gourgout, D. Aoki, A. Pourret, I. Sheikin, G. Seyfarth, J. Flouquet, and G. Knebel, Phys. Rev. Lett. 117, 206401 (2016). 10.1103/PhysRevLett.117.206401 CrossrefGoogle Scholar
  • 11 S. Ran, C. Eckberg, Q.-P. Ding, Y. Furukawa, T. Metz, S. R. Saha, I.-L. Liu, M. Zic, H. Kim, J. Paglione, and N. P. Butch, arXiv:1811.11808. Google Scholar
  • 12 S. Ikeda, H. Sakai, D. Aoki, Y. Homma, E. Yamamoto, A. Nakamura, Y. Shiokawa, Y. Haga, and Y. Ōnuki, J. Phys. Soc. Jpn. 75 [Suppl.], 116 (2006). 10.1143/JPSJS.75S.116 LinkGoogle Scholar
  • 13 (Supplemental Material) The field dependence of C/T is provided online. Google Scholar
  • 14 A. J. Leggett, Rev. Mod. Phys. 47, 331 (1975). 10.1103/RevModPhys.47.331 CrossrefGoogle Scholar
  • 15 V. P. Mineev and K. V. Samokhin, Introduction to Unconventional Superconductivity (Gordon and Breach, Amsterdam, 1999) Chap. 15. Google Scholar
  • 16 V. P. Mineev, Phys. Rev. B 81, 180504 (2010). 10.1103/PhysRevB.81.180504 CrossrefGoogle Scholar
  • 17 A. D. Hillier, J. Quintanilla, B. Mazidian, J. F. Annett, and R. Cywinski, Phys. Rev. Lett. 109, 097001 (2012). 10.1103/PhysRevLett.109.097001 CrossrefGoogle Scholar
  • 18 S. Takagi, Prog. Theor. Phys. 51, 1998 (1974). 10.1143/PTP.51.1998 CrossrefGoogle Scholar
  • 19 L. N. Bulaevskii, O. V. Dolgov, and M. O. Ptitsyn, Phys. Rev. B 38, 11290 (1988). 10.1103/PhysRevB.38.11290 CrossrefGoogle Scholar
  • 20 D. Aoki, W. Knafo, and I. Sheikin, C. R. Phys. 14, 53 (2013). 10.1016/j.crhy.2012.11.004 CrossrefGoogle Scholar
  • 21 W. Knafo, T. D. Matsuda, D. Aoki, F. Hardy, G. W. Scheerer, G. Ballon, M. Nardone, A. Zitouni, C. Meingast, and J. Flouquet, Phys. Rev. B 86, 184416 (2012). 10.1103/PhysRevB.86.184416 CrossrefGoogle Scholar
  • 22 B. Wu, G. Bastien, M. Taupin, C. Paulsen, L. Howald, D. Aoki, and J.-P. Brison, Nat. Commun. 8, 14480 (2017). 10.1038/ncomms14480 CrossrefGoogle Scholar
  • 23 N. D. Dung, T. D. Matsuda, Y. Haga, S. Ikeda, E. Yamamoto, T. Ishikura, T. Endo, S. Tatsuoka, Y. Aoki, H. Sato, T. Takeuchi, R. Settai, H. Harima, and Y. Ōnuki, J. Phys. Soc. Jpn. 78, 084711 (2009). 10.1143/JPSJ.78.084711 LinkGoogle Scholar