Antiferromagnetic Order and Magnetic Frustration in the Honeycomb Heavy-Fermion System Ce(Pt$_{1-x}$Pd$_{x}$)$_6$Al$_3$: $^{27}$Al and $^{195}$Pt NMR Studies

TL;DR

This study uses NMR techniques to explore how substituting Pd for Pt in Ce(Pt$_{1-x}$Pd$_{x}$)$_6$Al$_3$ affects its magnetic properties, revealing a transition from heavy-fermion behavior to antiferromagnetic order and highlighting the interplay between Kondo screening and magnetic frustration.

Contribution

It provides detailed NMR evidence of magnetic phase evolution in Ce(Pt$_{1-x}$Pd$_{x}$)$_6$Al$_3$, demonstrating a tunable transition from itinerant to localized antiferromagnetism.

Findings

Paramagnetic heavy-fermion state persists at x=0.

Pd substitution induces antiferromagnetic order at x=0.1, suppressing coherence temperature.

Crossover from itinerant to localized antiferromagnetism observed with increasing Pd content.

Abstract

Heavy-fermion systems with magnetic frustration offer a rich platform for investigating the interplay among Kondo screening, magnetic frustration, and quantum criticality. We report comprehensive $^{27}$Al and $^{195}$Pt nuclear magnetic resonance measurements on polycrystalline Ce(Pt$_{1-x}$Pd$_{x}$)$_6$Al$_3$ ($x = 0$, 0.1, 0.2, and 0.3). For $x = 0$, the Knight shift, linewidth, and nuclear spin-lattice relaxation rate reveal a paramagnetic heavy-fermion ground state persisting down to 0.1~K, characterized by a coherence temperature $T_{\mathrm{coh}} \simeq 15$~K. Substituting Pd induces antiferromagnetic order at $T_{\mathrm{N}} \simeq 3.5$~K, while suppressing $T_{\mathrm{coh}}$. Comparison between $x = 0.1$ and $x = 0.3$ reveals a crossover from itinerant spin-density-wave antiferromagnetism to more localized-moment antiferromagnetism, indicating a shift toward the localized side of the Doniach phase diagram. These findings establish Ce(Pt$_{1-x}$Pd$_{x}$)$_6$Al$_3$ as a tunable platform to explore the competition between Kondo screening and magnetic frustration.