Complex magnetism and strong electronic correlations in Ce2PdGe3

Abstract

Single crystal x-ray diffraction, magnetic susceptibility, heat capacity, and electrical resistivity measurements are reported for the new tetragonal compound Ce${}_2$PdGe${}_3$, which forms in the space group $P{4}_2/mmc$ (\#131) $-$ a relative of the $\hat{I}\pm$-ThSi${}_2$-type structure. Measurements reveal a two-part antiferromagnetic phase transition at $T_{\mathrm{N},1}$ $=$ 10.7 K and $T_{\mathrm{N},2}$ $=$ 9.6 K and subsequent ferromagnetic ordering near $T_{\mathrm{C}}$ $\approx$ 2.25 K. The ordered ground state emerges from a lattice of Ce ions that are hybridized with the conduction electrons, as revealed by the enhanced electronic coefficient of the specific heat ${\hat{I}}^3$ $\approx$ 50 mJ/mol-Ce-K${}^2$ (extrapolated to $T$ $=$ 0 for $T$ $<$ $T_{\mathrm{C}}$). Electronic structure calculations suggest that there is significant f-electron weight in the density of states near the Fermi energy and that the Fermi surface includes sheets with distinct nesting vectors. Chemical/structural disorder also plays an important role, as evidenced by results from single crystal x-ray diffraction, the width of the peaks in the heat capacity at $T_{\mathrm{N}}$ and $T_{\mathrm{C}}$, and the small residual resistivity ratio RRR $=$ $\ddot{I}{}_{300K}$/$\ddot{I}{}_0$ $=$ 1.8.

8 pages, 8 figures