NMR Investigation of antiferromagnetism and coherence in URu$_2$Si$_{2-x}$P$_x$

TL;DR

This study uses NMR to explore how phosphorus doping affects antiferromagnetism and electronic coherence in URu2Si2, revealing doping-dependent magnetic phases and electronic behavior.

Contribution

It provides new insights into the effects of P doping on magnetic order and coherence in URu2Si2, highlighting the role of chemical pressure without inhomogeneity.

Findings

Homogeneous antiferromagnetic phase at x=0.33 below 37 K

Anomaly in Knight shift at coherence temperature T*

Suppressed density of states at x=0.09 without long-range order

Abstract

We report $^{31}$P and $^{29}$Si NMR in single crystals of URu$_2$Si$_{2-x}$P$_x$ for $x=0.09$ and $x=0.33$. The spectra in the $x=0.33$ sample are consistent with a homogenous commensurate antiferromagnetic phase below $T_N \sim 37$ K. The Knight shift exhibits an anomaly at the coherence temperature, $T^*$, that is slightly enhanced with P doping. Spin lattice relaxation rate data indicate that the density of states is suppressed for $x=0.09$ below 30 K, similar to the undoped compound, but there is no evidence of long range order at this concentration. Our results suggest that Si substitution provides chemical pressure without inducing electronic inhomogeneity.