Crystallographic, Electronic, Thermal and Magnetic Properties of Single-Crystal SrCo2As2

Abstract

In tetragonal SrCo2As2 single crystals, inelastic neutron scattering measurements demonstrated that strong stripe-type antiferromagnetic (AFM) correlations occur at a temperature T = 5 K [W. Jayasekara et al., arXiv:1306.5174] that are the same as in the isostructural AFe2As2 (A = Ca, Sr, Ba) parent compounds of high-Tc superconductors. This surprising discovery suggests that SrCo2As2 may also be a good parent compound for high-Tc superconductivity. Here, structural and thermal expansion, electrical resistivity rho, angle-resolved photoemission spectroscopy (ARPES), heat capacity Cp, magnetic susceptibility chi, 75As NMR and neutron diffraction measurements of SrCo2As2 crystals are reported together with LDA band structure calculations that shed further light on this fascinating material. The c-axis thermal expansion coefficient alpha_c is negative from 7 to 300 K, whereas alpha_a is positive over this T range. The rho(T) shows metallic character. The ARPES measurements and band theory confirm the metallic character and in addition show the presence of a flat band near the Fermi energy E_F. The band calculations exhibit an extremely sharp peak in the density of states D(E_F) arising from a flat d_{x^2 - y^2} band. A comparison of the Sommerfeld coefficient of the electronic specific heat with chi(T = 0) suggests the presence of strong ferromagnetic itinerant spin correlations which on the basis of the Stoner criterion predicts that SrCo2As2 should be an itinerant ferromagnet, in conflict with the magnetization data. The chi(T) does have a large magnitude, but also exhibits a broad maximum at 115 K suggestive of dynamic short-range AFM spin correlations, in agreement with the neutron scattering data. The measurements show no evidence for any type of phase transition between 1.3 and 300 K and we propose that metallic SrCo2As2 has a gapless quantum spin-liquid ground state.

24 pages, 18 figures, 4 tables, 97 references; v2: updated Ref. 23 and corrected several typos; v3: minor revisions, published version. This is a companion paper to arXiv:1306.5174

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Cited by in corpus (40)

• Dynamical correlations and screened exchange on the experimental bench: spectral properties of the cobalt pnictide BaCo2As2
• Stripe Antiferromagnetic Spin Fluctuations in SrCo${}_2$As${}_2$
• Crystal and Magnetic Structure of CaCo{1.86}As2 Studied by X-ray and Neutron Diffraction
• Magnetic fluctuations and superconducting properties of CaKFe4As4 studied by 75As NMR
• Correlation between Superconductivity and Magnetic Fluctuations in Fe(Se1-xSx) Revealed by 77Se NMR
• Physical Properties of Metallic Antiferromagnetic CaCo{1.86}As2 Single Crystals
• EuCo2P2: A Model Molecular-Field Helical Heisenberg Antiferromagnet
• Frustrated magnetism in tetragonal CoSe, analogue to superconducting FeSe
• Antiferromagnetism in trigonal SrMn2As2 and CaMn2As2 single crystals
• Coexistence of ferromagnetic and stripe antiferromagnetic spin fluctuations in SrCo${}_2$As${}_2$
• Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals
• Non-Fermi-liquid behaviors associated with a magnetic quantum-critical point in Sr(Co{1-x}Ni{x})2As2 single crystals
• The suppression of electron correlations in the collapsed tetragonal phase of CaFe2As2 under ambient pressure demonstrated by 75As NMR-NQR measurements
• Crystallography and Physical Properties of BaCo2As2, Ba{0.94}K{0.06}Co2As2 and Ba{0.78}K{0.22}Co2As2
• Enhanced moments of Eu in single crystals of the metallic helical antiferromagnet EuCo{2-y}As2
• Metallic behavior induced by potassium doping of the trigonal antiferromagnetic insulator EuMn2As2
• Electronic structure and spin dynamics of ACo2As2 (A=Ba, Sr, Ca)
• Ferromagnetic cluster-glass phase in Ca(Co,Ir)2As2 crystals
• Pressure-induced collapsed-tetragonal phase in SrCo2As2
• Impact of Nematicity on the Relationship between Antiferromagnetic Fluctuations and Superconductivity in FeSe0.91S0.09 Under Pressure
• NMR Study of the New Magnetic Superconductor CaK(Fe$0.951Ni0.049)4As4: Microscopic Coexistence of Hedgehog Spin-vortex Crystal and Superconductivity
• Flat band magnetism and helical magnetic order in Ni-doped SrCo${}_2$As${}_2$
• NMR investigation of spin correlations in BaCo2As2
• Magnetic phase transitions in Eu(Co,Ni)2As2 single crystals
• Competing magnetic phases and itinerant magnetic frustration in SrCo${}_2$As${}_2$
• Antiferromagnetic spin correlations and pseudogap-like behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity
• Anomalous Composition-Induced Crossover in the Magnetic Properties of the Itinerant-Electron Antiferromagnet Ca{1-x}Sr{x}Co{2-y}As{2}
• Ba{0.4}Rb{0.6}Mn2As2: A Prototype Half-Metallic Ferromagnet
• Helical magnetic ordering in Sr(Co1-xNix)2As2
• Suppression of magnetic order in CaCo${}_{1.86}$As${}_2$ with Fe substitution: Magnetization, neutron diffraction, and x-ray diffraction studies of Ca(Co${}_{1-x}$Fe${}_x$)${}_y$As${}_2$
• Whether it is possible to stabilize the 1144-phase pnictides with tri-valence cations?
• Antiferromagnetic Stacking of Ferromagnetic Layers and Doping Controlled Phase Competition in Ca${}_{1-x}$Sr${}_x$Co${}_{2-y}$As${}_2$
• Interrelationships between nematicity, antiferromagnetic spin fluctuations and superconductivity: Role of hotspots in FeSe${}_{1-x}$S${}_x$ revealed by high pressure ${}^{77}$Se NMR study
• Suppression of ferromagnetism governed by a critical lattice parameter in CeTiGe$\_3$ with hydrostatic pressure or V substitution
• Influence of the surface symmetry breaking on the magnetism, collapsing and three dimensional dispersion of Co pnictides ACo2As2 (A=Ba, Sr, Ca)
• BaMn${}_2$P${}_2$: Highest magnetic ordering temperature 122-pnictide compound
• First-order phase transition to a nonmagnetic ground state in nonsymmorphic NbCrP
• Competing magnetic fluctuations and orders in a multiorbital model of doped SrCo${}_2$As${}_2$
• Suppression of antiferromagnetic order and strong ferromagnetic spin fluctuations in Ni-doped CaCo2As2 single crystals
• Absence of itinerant ferromagnetism in a cobalt-based oxypnictide