Metallic behavior induced by potassium doping of the trigonal antiferromagnetic insulator EuMn2As2

Abstract

We report magnetic susceptibility χ, isothermal magnetization M, heat capacity C_p and electrical resistivity ρmeasurements on undoped EuMn2As2 and K-doped Eu0.96K0.04Mn2As2 and Eu0.93K0.07Mn2As2 single crystals with the trigonal CaAl2Si2-type structure as a function of temperature T and magnetic field H. EuMn2As2 has an insulating ground state with an activation energy of 52 meV and exhibits antiferromagnetic (AFM) ordering of the Eu+2 spins S=7/2 at T_N1 = 15 K from C_p(T) and χ(T) data with a likely spin-reorientation transition at T_N2 = 5.0 K. The Mn+2 3d5 spins-5/2 exhibit AFM ordering at T_N = 142 K from all three types of measurements. The M(H) isotherm and χ(T) data indicate that the Eu AFM structure is both noncollinear and noncoplanar. The AFM structure of the Mn spins is also unclear. A 4% substitution of K for Eu in Eu0.96K0.04Mn2As2 is sufficient to induce a metallic ground state. Evidence is found for a difference in the AFM structure of the Eu moments in the metallic crystals from that of undoped EuMn2As2 versus both T and H. For metallic Eu0.96K0.04Mn2As2 and Eu0.93K0.07Mn2As2, an anomalous S-shape T dependence of ρrelated to the Mn magnetism is found. Upon cooling from 200 K, ρexhibits a strong negative curvature, reaches maximum positive slope at the Mn T_N ~ 150 K, and then continues to decrease but more slowly below T_N. This suggests that dynamic short-range AFM order of the Mn spins above the Mn T_N strongly suppresses the resistivity, contrary to the conventional decrease of ρthat is only observed upon cooling below T_N of an antiferromagnet.

21 pages, 22 figures, 4 Tables

References in corpus (20)

• Antiferromagnetic order and spin dynamics in iron-based superconductors
• High Temperature Superconductivity in Iron Pnictides and Chalcogenides
• Iron-Based Superconductors: current status of materials and pairing mechanism
• Superconductivity induced by phosphorus doping and its coexistence with ferromagnetism in EuFe${}_2$(As${}_{0.7}$P${}_{0.3}$)${}_2$
• High-Temperature Superconductivity in Eu0.5K0.5Fe2As2
• Antiferromagnetic transition in EuFe${}_2$As${}_2$: A possible parent compound for superconductors
• Possible re-entrant superconductivity in EuFe2As2 under pressure
• Electronic structure and Magnetism in BaMn${}_2$As${}_2$ and BaMn${}_2$Sb${}_2$
• Spin fluctuations in iron pnictides and chalcogenides: From antiferromagnetism to superconductivity
• Unified Molecular Field Theory for Collinear and Noncollinear Heisenberg Antiferromagnets
• Magnetic Dipole Interactions in Crystals
• Properties of single crystalline AZn2Sb2 (A=Ca,Eu,Yb)
• Properties of Binary Transition-Metal Arsenides (TAs)
• Antiferromagnetism in EuCu2As2 and EuCu1.82Sb2 Single Crystals
• CaMn${}_2$Sb${}_2$: Spin waves on a frustrated antiferromagnetic honeycomb lattice
• Magnetic ground state of superconducting Eu(Fe0.88Ir0.12)2As2: A combined neutron diffraction and first-principles calculation study
• From Hunds insulator to Fermi liquid: Optical spectroscopy study of K doping in BaMn${}_2$As${}_2$
• Crystallography and Physical Properties of BaCo2As2, Ba{0.94}K{0.06}Co2As2 and Ba{0.78}K{0.22}Co2As2
• $\mu$SR and Neutron Diffraction Investigations on Reentrant Ferromagnetic Superconductor Eu(Fe{0.86}Ir{0.14})2As2
• Ba{0.4}Rb{0.6}Mn2As2: A Prototype Half-Metallic Ferromagnet

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