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

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 EuT5In (T = Cu, Ag, Au) are gauged against relevant experiments. The EuT5In compounds adopt a different structure for each different coinage metal-EuCu5In (hR42; R (3) over barm, a = 5.0933(7), c = 30.557(6) angstrom), EuAg5In (oP28; Pnma, a = 9.121(2), b = 5.645(1), c = 11.437(3) angstrom), and EuAu5In (tI14; I4/mmm, a = 7.1740(3), c = 5.4425(3) angstrom)-and crystallize with the Sr5Al9, CeCu6, and YbMo2Al4 structure types, respectively. EuCu5In and EuAg5In order antiferromagnetically at T-N = 12 and 6 K, respectively, whereas EuAu5In is ferromagnetic below T-C = 13 K. EuCu5In exhibits complex magnetism: after the initial drop at TN, the magnetization rises again below 8 K, and a weak metamagnetic-like transition occurs at 2 K in mu H-0 = 1.8 T. The electronic heat capacity of EuCu5In, gamma = similar to 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 4f and 5d 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.