EuZn2Si2 and EuZn2Ge2 Grown from Zn or Ga(ln)/Zn Flux

Single crystals of the novel ternary compounds EuZn2Si2 and EuZn2Ge2 were grown from pure gallium, indium, or zinc metal used as a flux solvent. Crystal properties were characterized using X-ray single-crystal analyses via Gandolfi and Weissenberg film techniques and by four-circle X-ray single-crystal diffractometry. The new compounds crystallize with ternary derivative structures of BaAl4, i.e., EuZn2Si2 with ThCr2Si2-type (a=0.42607(2) nm, c=1.03956(5) nm, I4/mmm, R1 =0.038) and EuZn2Ge2 with CaBe2Ge2-type (a=0.43095(2) nm, c=1.07926(6) nm, P4/nmm, R1=0.067). XAS and magnetic measurements on EuZn2Si2 and EuZn2Ge2 revealed in both compounds the presence of Eu2+ ions carrying large magnetic moments, which order magnetically at low temperatures. The magnetic phase transition occurs at TN=16 and 7.5 K for the silicide and the germanide, respectively. In EuZn2Si2 there occurs a spin reorientation at 13 K and furthermore some canting of antiferromagnetically ordered moments below about 10 K. In EuZn2Ge2 a canted antiferromagnetic structure is formed just at TN.