Magnetic and thermodynamic properties of Cu${}_x$TiSe${}_2$ single crystals

Abstract

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 $2{\Delta }_s\sim [2.4-2.8]k_B{T}_c$, regardless of the copper content, in puzzling contradiction with specific heat measurements which can be well described by one single large gap $2{\Delta }_l\sim [3.7-3.9]k_B{T}_c$. Finally, our measurements reveal a non-trivial doping dependence of the condensation energy, which remains to be understood.

arXiv comment9 pages, 7 figures

References in corpus (26)

• Long-range incommensurate charge fluctuations in (Y,Nd)Ba2Cu3O(6+x)
• Direct observation of competition between superconductivity and charge density wave order in YBa2Cu3Oy
• Superconductivity in Cu_xTiSe_2
• Magnetic-field-induced charge-stripe order in the high temperature superconductor YBa2Cu3Oy
• Evidence for an excitonic insulator phase in 1T-TiSe${}_2$
• Two Gaps Make a High Temperature Superconductor?
• Superconducting density of states and vortex cores of 2H-NbS2
• Two energy gaps and Fermi surface 'arcs' in NbSe2
• Quasi-Particle Spectra, Charge-Density-Wave, Superconductivity and Electron-Phonon Coupling in 2H-NbSe2
• Penetration depth study of superconducting gap structure of 2\textit{H}-NbSe${}_2$
• Momentum-resolved superconducting gap in the bulk of Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ from combined ARPES and $\mu$SR measurements
• Strong anharmonicity induces quantum melting of charge density wave in 2H-NbSe$\_2$ under pressure
• Emergence of Fermi pockets in an excitonic CDW melted novel superconductor
• Observation of a Charge Density Wave Incommensuration Near the Superconducting Dome in CuxTiSe2
• Thermodynamic phase diagram of Fe(Se${}_{0.5}$Te${}_{0.5}$) single crystals up to 28 Tesla
• Anharmonic suppression of Charge density wave in 2H-NbS${}_2$
• Specific-heat measurements of superconducting NbS2 single crystal in an external magnetic field: Study on the energy gap structure
• Superconducting dome in MoS2 and TiSe2 generated by quasiparticle-phonon coupling
• Exciton-phonon interactions and superconductivity bordering charge order in TiSe2
• Heat Capacity of Single Crystal CuxTiSe2 Superconductors
• Revisiting the vortex-core tunnelling spectroscopy in YBa${}_2$Cu${}_3$O${}_{7-\delta }$
• In-plane magnetic penetration depth in NbS${}_2$
• S-wave superconductivity probed by measuring magnetic penetration depth and lower critical field of MgCNi${}_3$ single crystals
• Puzzling evidence for surface superconductivity in the layered dichalcogenide Cu${}_{10\%}$TiSe${}_2$
• Scaling of the physical properties in Ba(Fe,Ni)2As2 single crystals: Evidence for quantum fluctuations
• Comment on "Precision global measurements of London penetration depth in FeTe${}_{0.58}$Se${}_{0.42}$"

Cited by in corpus (5)

• Critical current in thin flat superconductors with Bean-Livingston and geometrical barriers
• Emergent superconductivity upon disordering a charge density wave ground state
• Determination of the magnetic penetration depth with measurements of the vortex-penetration field for type-II superconductors
• Enhancement of vortex liquid phase and reentrant behavior in NiBi3 single crystals
• Determination of the London penetration depth with the tunnel diode oscillator technique