Investigation of the physical properties of the tetragonal CeMAl4Si2 (M = Rh, Ir, Pt) compounds

Abstract: The synthesis, crystal structure, and physical properties studied by means of x-ray diffraction, magnetic, thermal and transport measurements of CeMAl${4}$Si${2}$ (M = Rh, Ir, Pt) are reported, along with the electronic structure calculations for LaMAl${4}$Si${2}$ (M = Rh, Ir, Pt). These materials adopt a tetragonal crystal structure (space group P4/mmm) comprised of BaAl$4$ blocks, separated by MAl$_2$ units, stacked along the $c$-axis. Both CeRhAl${4}$Si${2}$ and CeIrAl${4}$Si${2}$ order antiferromagnetically below $T{N1}$=14 and 16 K, respectively, and undergo a second antiferromagnetic transitition at lower temperature ($T_{N2}$=9 and 14 K, respectively). CePtAl${4}$Si${2}$ orders ferromagnetically below $T_C$ =3 K with an ordered moment of $\mu_{sat}$=0.8 $\mu_{B}$ for a magnetic field applied perpendicular to the $c$-axis. Electronic structure calculations reveal quasi-2D character of the Fermi surface.