Filling the holes in the CaFe$_{4}$As$_{3}$ structure: synthesis and magnetism of CaCo$_{5}$As$_{3}$

摘要

Here we investigate single crystals of CaCo$_{5}$As$_{3}$ by means of singlecrystal X-ray diffraction, microprobe, magnetic susceptibility, heat capacity,and pressure-dependent transport measurements. CaCo$_{5}$As$_{3}$ shares thesame structure of CaFe$_{4}$As$_{3}$ with an additional Co atom filling alattice vacancy and undergoes a magnetic transition at $T_{M} = 16$ Kassociated with a frustrated magnetic order. CaCo$_{5}$As$_{3}$ displaysmetallic behavior and its Sommerfeld coefficient ($\gamma = 70$ mJ/mol.K$^{2}$)indicates a moderate enhancement of electron-electron correlations. Transportdata under pressures to $2.5$ GPa reveal a suppression of $T_{M}$ at a rate of$-0.008$ K/GPa. First-principle electronic structure calculations show acomplex 3D band structure and magnetic moments that depend on the localenvironment at each Co site. Our results are compared with previous data onCaFe$_{4}$As$_{3}$ and provide a scenario for a magnetically frustrated groundstate in this family of compounds.