Anisotropic Fully-Gapped Superconductivity Possibly Mediated by Charge Fluctuations in a Nondimeric Organic Complex

Abstract

We investigate low-temperature electronic properties of the nondimeric organic superconductor ${\beta }^{\prime \prime }$-(BEDT-TTF)${}_4$[(H${}_3$O)Ga(C${}_2$O${}_4$)${}_3$]PhNO${}_2$. By examining ultrasonic properties, charge disproportionation (CD) without magnetic field dependence is detected below $T_{\mathrm{CD}}$$\sim$8~K just above the superconducting critical temperature $T_{\mathrm{c}}$$\sim$6~K. From quantum oscillations in high fields, we find variation in the Fermi surface and mass enhancement induced by the CD. Heat capacity studies elucidate that the superconducting gap function is fully gapped in the Fermi surface, but anisotropic with fourfold symmetry. We point out that the pairing mechanism of the superconductivity is possibly dominated by charge fluctuations.

arXiv comment6 figures

References in corpus (15)

• Superconductivity mediated by charge fluctuations in layered molecular crystals
• kappa-(BEDT-TTF)_2Cu[N(CN)_2]Br: a Fully Gapped Strong-Coupling Superconductor
• d_{x^2-y^2}- vs. d_{xy}- like pairings in organic superconductors κ-(BEDT-TTF)_2 X
• Orientational field-dependence of low-lying excitations in mixed state of unconventional superconductors
• Charge fluctuation induced superconducting state in two-dimensional quarter-filled electron systems
• Near-degeneracy of extended $s+d_{x^2-y^2}$ and $d_{xy}$ order parameters in quasi-two-dimensional organic superconductors
• Specific Heat vs Field in the 30 K Superconductor BaFe2(As0.7P0.3)2
• Charge-order fluctuations and superconductivity in two-dimensional organic metals
• Verification of Anisotropic s-Wave Superconducting Gap Structure in CeRu2 from Low-Temperature Field-Angle-Resolved Specific Heat Measurements
• 13C NMR study of superconductivity near charge instability realized in beta"-(BEDT-TTF)4[(H3O)Ga(C2O4)3]C6H5NO2
• Effects of Electron Correlations and Chemical Pressures on Superconductivity of ${\beta }^{\prime \prime }$-type Organic Compounds
• Microscopic coexistence of superconductivity and charge order in organic superconductor ${\beta }^{\prime \prime }$-(BEDT-TTF)${}_4$[(H${}_3$O)Ga(C${}_2$O${}_4$)${}_3$]$\cdot$C${}_6$H${}_5$NO${}_2$
• Effects of Pnictogen Atmosphere Annealing in Fe${}_{1+y}$Te${}_{0.6}$Se${}_{0.4}$
• Microwave Conductivity Distinguishes Between Different d-wave States: Umklapp Scattering in Unconventional Superconductors
• Charge fluctuations and superconductivity in organic conductors: the case of $\beta "$-(BEDT-TTF)${}_2$SF${}_5$CH${}_2$CF${}_2$SO${}_3$

Cited by in corpus (2)

• Thermodynamic evidence for the formation of a Fulde-Ferrell-Larkin-Ovchinnikov phase in the organic superconductor $\lambda$-(BETS)${}_2$GaCl${}_4$
• Removal of excess iron by annealing processes and emergence of bulk superconductivity in sulfur-substituted FeTe