Complex magnetism and strong electronic correlations in Ce2PdGe3

TL;DR

This study investigates the complex magnetic behavior and electronic correlations in the new tetragonal compound Ce2PdGe3, revealing multiple magnetic phase transitions, hybridized electronic states, and significant f-electron contributions near the Fermi level.

Contribution

It reports the synthesis and detailed characterization of Ce2PdGe3, highlighting its unique magnetic phases, electronic structure, and the role of structural disorder, which advances understanding of correlated electron systems in this class.

Findings

Two antiferromagnetic transitions at 10.7 K and 9.6 K.

Ferromagnetic ordering near 2.25 K.

Enhanced electronic specific heat coefficient indicating strong correlations.

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 $P4_{2}/mmc$ (\#131) $-$ a relative of the $\alpha$-ThSi$_2$-type structure. Measurements reveal a two-part antiferromagnetic phase transition at $T_{\rm{N,1}}$ $=$ 10.7 K and $T_{\rm{N,2}}$ $=$ 9.6 K and subsequent ferromagnetic ordering near $T_{\rm{C}}$ $\approx$ 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 $\gamma$ $\approx$ 50 mJ/mol-Ce-K$^2$ (extrapolated to $T$ $=$ 0 for $T$ $<$ $T_{\rm{C}}$). 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 $T_{\rm{N}}$ and $T_{\rm{C}}$, and the small residual resistivity ratio RRR $=$ $\rho_{\rm{300K}}$/$\rho_{\rm{0}}$ $=$ 1.8.