Switching of the magnetic order in CeRhIn$_{5-x}$Sn$_{x}$ in the vicinity of its quantum critical point

TL;DR

This study investigates how magnetic order in CeRhIn$_{5-x}$Sn$_{x}$ evolves near its quantum critical point, revealing a switch from incommensurate to commensurate antiferromagnetic order as Sn concentration increases.

Contribution

The paper provides the first neutron diffraction evidence of a magnetic order switch in CeRhIn$_{5-x}$Sn$_{x}$ near its quantum critical point, highlighting a change in magnetic propagation vector.

Findings

Magnetic propagation vector shifts from incommensurate to commensurate near x=0.30.

Incommensurate wave vector increases with Sn concentration.

Magnetic order changes abruptly at x=0.30.

Abstract

We report neutron diffraction experiments performed in the tetragonal antiferromagnetic heavy fermion system CeRhIn$_{5-x}$Sn$_{x}$ in its ($x$, $T$) phase diagram up to the vicinity of the critical concentration $x_c$ $\approx$ 0.40, where long range magnetic order is suppressed. The propagation vector of the magnetic structure is found to be $\bf{k_{IC}}$=(1/2, 1/2, $k_l$) with $k_l$ increasing from $k_l$=0.298 to $k_l$=0.410 when $x$ increases from $x$=0 to $x$=0.26. Surprisingly, for $x$=0.30, the order has changed drastically and a commensurate antiferromagnetism with $\bf{k_{C}}$=(1/2, 1/2, 0) is found. This concentration is located in the proximity of the quantum critical point where superconductivity is expected.