Magnetocaloric Behavior in Ternary Europium Indides EuT₅In: Probing the Design Capability of First-Principles-Based Methods on the Multifaceted Magnetic Materials

High Resolution Image Download MS PowerPoint Slide The most favorable structures and the types of magnetic ordering predicted from first-principles-based methods in a family of closely related transition-metal-rich indides EuT 5 In (T = Cu, Ag, Au) are gauged against relevant experiments. The EuT 5 In compounds adopt a different structure for each different coinage metal—EuCu 5 In ( hR 42; R 3̅ m, a = 5.0933(7), c = 30.557(6) Å), EuAg 5 In ( oP 28; Pnma, a = 9.121(2), b = 5.645(1), c = 11.437(3) Å), and EuAu 5 In ( tI 14; I 4/ mmm, a = 7.1740(3), c = 5.4425(3) Å)—and crystallize with the Sr 5 Al 9, CeCu 6, and YbMo 2 Al 4 structure types, respectively. EuCu 5 In and EuAg 5 In order antiferromagnetically at T N = 12 and 6 K, respectively, whereas EuAu 5 In is ferromagnetic below T C = 13 K. EuCu 5 In exhibits complex magnetism: after the initial drop at T N, the magnetization rises again below 8 K, and a weak metamagnetic-like transition occurs at 2 K in μ 0 H = 1.8 T. The electronic heat capacity of EuCu 5 In, γ = ∼400 mJ/(mol K 2 ), points to strong electronic correlations. Spin-polarized densities of states suggest that the magnetic interactions in the three materials studied are supported via mixing 4 f and 5 d states of Eu. A chemical bonding analysis based on the Crystal Orbital Hamilton populations reveals the tendency to maximize overall bonding as a driving force to adopt a particular type of crystal structure.