Strong anisotropy in nearly ideal-tetrahedral superconducting FeS single crystals

Abstract

We report the novel preparation of single crystals of tetragonal iron sulfide, FeS, which exhibits a nearly ideal tetrahedral geometry with S--Fe--S bond angles of 110.2(2) ${}^{\circ }$ and 108.1(2) ${}^{\circ }$. Grown via hydrothermal de-intercalation of K${}_x$Fe${}_{2-y}$S${}_2$ crystals under basic and reducing conditions, the silver, plate-like crystals of FeS remain stable up to 200 ${}^{\circ }$C under air and 250 ${}^{\circ }$C under inert conditions, even though the mineral "mackinawite" (FeS) is known to be metastable. FeS single crystals exhibit a superconducting state below $T_c=4$ K as determined by electrical resistivity, magnetic susceptibility, and heat capacity measurements, confirming the presence of a bulk superconducting state. Normal state measurements yield an electronic specific heat of 5~mJ/mol-K${}^2$, and paramagnetic, metallic behavior with a low residual resistivity of 250~$\mu \Omega \cdot$cm. Magnetoresistance measurements performed as a function of magnetic field angle tilted toward both transverse and longitudinal orientations with respect to the applied current reveal remarkable two-dimensional behavior. This is paralleled in the superconducting state, which exhibits the largest known upper critical field $H_{c2}$ anisotropy of all iron-based superconductors, with $H_{c2}^{||ab}(0)/H_{c2}^{||c}(0)=$(2.75~T)/(0.275~T)=10. Comparisons to theoretical models for 2D and anisotropic-3D superconductors, however, suggest that FeS is the latter case with a large effective mass anisotropy. We place FeS in context to other closely related iron-based superconductors and discuss the role of structural parameters such as anion height on superconductivity.

References in corpus (14)

• High-temperature superconductivity in iron-based materials
• Density functional study of FeS, FeSe and FeTe: Electronic structure, magnetism, phonons and superconductivity
• Extreme Sensitivity of Superconductivity to Stoichiometry in FeSe (Fe1+dSe)
• Incommensurate magnetic order in the alpha-Fe(Te,Se) superconductor systems
• Why Does Undoped FeSe Become A High Tc Superconductor Under Pressure?
• Superconductivity in S-substituted FeTe
• From (pi, 0) magnetic order to superconductivity with (pi, pi) magnetic resonance in Fe1.02(Te1-xSex)
• Origin of the tetragonal-to-orthorhombic (nematic) phase transition in FeSe: a combined thermodynamic and NMR study
• Soft chemical control of superconductivity in lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe
• Phase relations in K_xFe_{2-y}Se_2 and the structure of superconducting K_xFe_2Se_2 via high-resolution synchrotron diffraction
• Superconducting properties of sulfur-doped iron selenide
• Magnetic ordering in mackinawite (tetragonal FeS): evidence for strong itinerant spin fluctuations
• Spin glass behavior of insulating K0.8Fe2-xS2
• Crystal structure, physical properties and superconductivity in $A_x$Fe${}_2$Se${}_2$ single crystals

Cited by in corpus (28)

• Nematicity, magnetism and superconductivity in FeSe
• The intercalation chemistry of layered iron chalcogenide superconductors
• Suppression of superconductivity and enhanced critical field anisotropy in thin flakes of FeSe
• Superconductivity and magnetism in Iron Sulfides Intercalated by Metal Hydroxides
• FeS: Structure and Composition Relations to Superconductivity and Magnetism
• Coexistence of low moment magnetism and superconductivity in tetragonal FeS and suppression of $T_{\mathrm{c}}$ under pressure
• Frustrated magnetism in tetragonal CoSe, analogue to superconducting FeSe
• The magnetic and electronic properties of Oxyselenides - influence of transition metal ions and lanthanides
• Two-dome superconductivity in FeS induced by a Lifshitz transition
• Hydrothermal synthesis and complete phase diagram of FeSe${}_{1-x}$S${}_x$ $(0\le x\le 1)$ single crystals
• Ionic-liquid-gating induced protonation and superconductivity in FeSe, FeSe0.93S0.07, ZrNCl, 1T-TaS2, and Bi2Se3
• Critical current density and vortex pinning in tetragonal FeS${}_{1-x}$Se${}_x$ ($x=0,0.06$)
• Robustness of superconductivity to competing magnetic phases in tetragonal FeS
• Spin excitations and the Fermi surface of superconducting FeS
• Strong coupling superconductivity revealed by scanning tunneling microscope in tetragonal FeS
• Upper critical field and quantum oscillations in tetragonal superconducting FeS
• Topological crystalline antiferromagnetic state in tetragonal FeS
• Suppression of Superconductivity and Nematic Order in Fe${}_{1-y}$Se${}_{1-x}$S${}_x$ (0$\le$$x$$\le$1, $y$$\le$0.1) Crystals by Anion Height Disorder
• Nodal superconductivity coexists with low-moment static magnetism in single-crystalline tetragonal FeS: A muon spin relaxation and rotation study
• Observation of a C-type short range antiferromagnetic order in expanded FeS
• Thermoelectricity and electronic correlations enhancement in FeS by slight Se substitution
• Molecular Beam Epitaxy Growth of Tetragonal FeS Film on SrTiO3(001) Substrate
• Accurate determination of the Fermi surface of tetragonal FeS via quantum oscillation measurements and quasiparticle self-consistent \textit{GW} calculations
• Stabilization and heteroepitaxial growth of metastable tetragonal FeS thin films by pulsed laser deposition
• Observation of two distinct superconducting domes under pressure in tetragonal FeS
• Upper critical fields in high-$T_{\mathrm{c}}$ superconductors
• Dimensionality of the superconductivity in the transition metal pnictide WP
• Electronic and Superconducting Properties of Some FeSe-based Single Crystals and Films Grown Hydrothermally