Magnetic and thermodynamic properties of Cu$_x$TiSe$_2$ single crystals
| Autor: | Pribulová, Z., Medvecká, Z., Kačmarčík, J., Komanický, V., Klein, T., Rodière, P., Levy-Bertrand, F., Michon, B., Marcenat, C., Husaníková, P., Cambel, V., Šoltýs, J., Karapetrov, G., Borisenko, S., Evtushinsky, D., Berger, H., Samuely, P. |
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| Rok vydání: | 2017 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 95, 174512 (2017) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.95.174512 |
| Popis: | We present a detailed study of the phase diagram of copper intercalated TiSe$_2$ single crystals, combining local Hall-probe magnetometry, tunnel diode oscillator technique (TDO), specific-heat, and angle-resolved photoemission spectroscopy measurements. A series of the Cu$_x$TiSe$_2$ samples from three different sources with various copper content $x$ and superconducting critical temperatures $T_c$ have been investigated. We first show that the vortex penetration mechanism is dominated by geometrical barriers enabling a precise determination of the lower critical field, $H_{c1}$. We then show that the temperature dependence of the superfluid density deduced from magnetic measurements (both $H_{c1}$ and TDO techniques) clearly suggests the existence of a small energy gap in the system, with a coupling strength $2\Delta_s \sim [2.4-2.8]k_BT_c$, regardless of the copper content, in puzzling contradiction with specific heat measurements which can be well described by one single large gap $2\Delta_l \sim [3.7-3.9]k_BT_c$. Finally, our measurements reveal a non-trivial doping dependence of the condensation energy, which remains to be understood. Comment: 9 pages, 7 figures |
| Databáze: | arXiv |
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