Gap structure of FeSe determined by field-angle-resolved specific heat measurements

Abstract

Quasiparticle excitations in FeSe were studied by means of specific heat ($C$) measurements on a high-quality single crystal under rotating magnetic fields. The field dependence of $C$ shows three-stage behavior with different slopes, indicating the existence of three gaps (${\Delta }_1$, ${\Delta }_2$, and ${\Delta }_3$). In the low-temperature and low-field region, the azimuthal-angle ($\varphi$) dependence of $C$ shows a four-fold symmetric oscillation with sign change. On the other hand, the polar-angle ($\theta$) dependence manifests as an anisotropy-inverted two-fold symmetry with unusual shoulder behavior. Combining the angle-resolved results and the theoretical calculation, the smaller gap ${\Delta }_1$ is proved to have two vertical-line nodes or gap minima along the $k_z$ direction, and is determined to reside on the electron-type $\epsilon$ band. ${\Delta }_2$ is found to be related to the electron-type $\delta$ band, and is isotropic in the $ab$-plane but largely anisotropic out of the plane. ${\Delta }_3$ residing on the hole-type $\alpha$ band shows a small out-of-plane anisotropy with a strong Pauli-paramagnetic effect.

arXiv comment6 pages, 3 figures

References in corpus (34)

• Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3
• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Superconductivity at 36 K in beta-Fe1.01Se with the compression of the interlayer separation under pressure
• Pressure evolution of low-temperature crystal structure and bonding of 37 K $T_c$ FeSe superconductor
• The Structural Phase Transition in FeSe (Fe1+dSe)
• Enhancement of superconducting transition temperature of FeSe by intercalation of a molecular spacer layer
• Field-induced superconducting phase of FeSe in the BCS-BEC cross-over
• Discovery of Orbital-Selective Cooper Pairing in FeSe
• Thermodynamic evidence for nematic superconductivity in Cu${}_x$Bi${}_2$Se${}_3$
• Specific heat of single crystal MgB_2: a two-band superconductor with two different anisotropies
• Anomalous Fermi surface in FeSe seen by Shubnikov-de Haas oscillation measurements
• Gap Structure of the Spin-Triplet Superconductor Sr2RuO4 Determined from the Field-Orientation Dependence of Specific Heat
• Sign reversal of field-angle resolved heat capacity oscillations in a heavy fermion superconductor CeCoIn${}_5$ and $d_{x^2-y^2}$ pairing symmetry
• Evidence for unidirectional nematic bond ordering in FeSe
• Multiband superconductivity with unexpected deficiency of nodal quasiparticles in CeCu2Si2
• Coexistence of isotropic s-wave and extended s-wave order parameters in FeSe as revealed by the low-temperature specific heat
• Temperature dependence of lower critical field Hc1(T) shows nodeless superconductivity in FeSe
• Sign-reversing orbital polarization in the nematic phase of FeSe due to the $C_2$ symmetry-breaking in the self-energy
• Distinctive momentum dependence of the band reconstruction in the nematic state of FeSe thin film
• Critical current density, vortex dynamics, and phase diagram of FeSe single crystal
• Specific heat evidence for two-gap superconductivity in ternary-iron silicide Lu${}_2$Fe${}_3$Si${}_5$
• Nodal structure of quasi-2D superconductors probed by magnetic field
• Anisotropic Structure of the Order Parameter in FeSe0.45Te0.55 Revealed by Angle Resolved Specific Heat
• Field dependence of the zero energy density of states around vortices in an anisotropic gap superconductor
• Highly anisotropic and two-fold symmetric superconducting gap in nematically ordered FeSe${}_{0.93}$S${}_{0.07}$
• Electron carriers with possible Dirac-cone-like dispersion in FeSe${}_{1-x}$S${}_x$ ($x$ = 0 and 0.14) single crystals triggered by structural transition
• Evidence for time-reversal symmetry breaking of the superconducting state near twin-boundary interfaces in FeSe
• Superconducting gap structure of FeSe
• Thermal Conductivity of the Iron-Based Superconductor FeSe : Nodeless Gap with Strong Two-Band Character
• Evidence for chiral d-wave superconductivity in URu2Si2 from the field-angle variation of its specific heat
• Vortex State and Field-Angle Resolved Specific Heat Oscillation for H // ab in d-Wave Superconductors
• Verification of Anisotropic s-Wave Superconducting Gap Structure in CeRu2 from Low-Temperature Field-Angle-Resolved Specific Heat Measurements
• Hidden Crossover Phenomena in Strongly Pauli Limited Multiband Superconductors ---Application to CeCu${}_2$Si${}_2$
• Nodal gap detection through polar angle-resolved density of states measurements in uniaxial superconductors

Cited by in corpus (24)

• On the Remarkable Superconductivity of FeSe and its Close Cousins
• Nematic Pairing from Orbital Selective Spin Fluctuations in FeSe
• Electronic nematic states tuned by isoelectronic substitution in bulk FeSe1-xSx
• Scaling of the superconducting gap with orbital character in FeSe
• Quasi-particle evidence for the nematic state above $T_{\mathrm{c}}$ in Sr${}_x$Bi${}_2$Se${}_3$
• Evidence for nematic superconductivity of topological surface states in PbTaSe2
• Nodal gaps in the nematic superconductor FeSe from heat capacity
• Bulk superconductivity and role of fluctuations in the iron-based superconductor FeSe at high pressures
• Hydrothermal synthesis and complete phase diagram of FeSe${}_{1-x}$S${}_x$ $(0\le x\le 1)$ single crystals
• Observation of the in-plane magnetic field-induced phase transitions in FeSe
• Evidence of nodal gap structure in the basal plane of the FeSe superconductor
• Electronic transport properties and hydrostatic pressure effect of FeSe${}_{0.67}$Te${}_{0.33}$ single crystals free of phase separation
• Vortex-lattice melting and paramagnetic depairing in the nematic superconductor FeSe
• FeSe and the missing electron pocket problem
• Influence of disorder on the signature of pseudogap and multigap superconducting behavior in FeSe
• Disorder-sensitive node-like small gap in FeSe
• Disorder-robust high-field superconducting phase of FeSe single crystals
• Synergy and competition between superconductivity and antiferromagnetism in FeSe under pressure
• Multi-band description of the upper critical field of bulk FeSe
• Suppression of Superconductivity in Heavy-ion Irradiated 2H-NbSe2 Caused by Negative Pressure
• Fully gapped superconductivity without sign reversal in the topological superconductor PbTaSe${}_2$
• Impact of Disorder on the Superconducting Properties and BCS-BEC Crossover in FeSe Single Crystals
• Specific Heat and the gap structure of a Nematic Superconductor, application to FeSe
• Multiple magnetic orders discovered in the superconducting state of EuFe${}_2$(As${}_{1-x}$P${}_x$)${}_2$