Layered transition-metal pnictide SrMnBi2with metallic blocking layer

Abstract

The physical properties and the band structure of the layered pnictide SrMnBi 2 were investigated. This compound has a crystal structure similar to that of the superconducting Fe pnictides, and is a bad metal with large residual resistivity. Magnetic order sets in at very high temperatures, around 290 K, as shown by magnetization, resistivity, and specific heat data. Band structure calculations using density functional theory (DFT) are consistent with the thermodynamic and transport measurements, suggesting a checkerboard antiferromagnetic (cAFM) ground state and a localized picture for the magnetism. Moreover, DFT results indicate that the Mn 3d electrons are strongly correlated, and that, unlike in the known superconductors, the Sr-Bi (1) layer is metallic. One more notable feature of the DFT calculation is the multiple Dirac-cone-like dispersion close to the Fermi level.

Coupling of magnetic order to planar Bi electrons in the anisotropic Dirac metalsAMnBi2 (A =Sr,Ca)

“…Interestingly, the Dirac cones are highly anisotropic in the xy plane, due to weak hybridization with A site d xy,yz orbitals. A substantial amount of experimental evidence for anisotropic Dirac fermions in the Bi layer exists from measurements of magnetization, magnetotransport, angle-resolved photoemission spectra (ARPES) and magnetothermopower 3,4,8,[10][11][12][13] . Other bands predicted by DFT are also seen in ARPES.…”

Phase stability and large in-plane resistivity anisotropy in the 112-type iron-based superconductor Ca1−xLaxFeAs2

“…[6], where it was pointed out that this structure would support metallic spacer layers which could aid in elucidating the mechanism for high temperature superconductivity. Attempts to synthesize iron pnictide compounds in this structure were not originally successful, but new Mn based materials in this structure were found [7,8] and it was observed theoretically [7] and experimentally [8][9][10][11] that the spacer layers exhibit Dirac cones [12]. Recently, Fe superconductors in the 112 structure were synthesized, (Ca,Pr)FeAs 2 [13], and Ca 1−x La x FeAs 2 [14].…”

Valley-Polarized Interlayer Conduction of Anisotropic Dirac Fermions inSrMnBi2

“…Among various Dirac materials, SrMnBi 2 is of particular interest because of its highly anisotropic quasitwo-dimensional (2D) Fermi surface (FS) [11][12][13][14][15]. In SrMnBi 2 , four valley-degenerate Dirac cones are on the Γ-M symmetry lines in the Brillouin zone, which has distinct energy dispersion against the momentum direction.…”