Novel phase diagram for antiferromagnetism and superconductivity in pressure-induced heavy-fermion superconductor Ce$_2$RhIn$_8$ probed by In-NQR

TL;DR

This study maps the pressure-dependent phase diagram of Ce$_2$RhIn$_8$, revealing a transition from 2D to 3D antiferromagnetic fluctuations and identifying the pressure range where superconductivity occurs with a maximum critical temperature near the quantum critical point.

Contribution

It provides the first detailed pressure phase diagram of Ce$_2$RhIn$_8$ using In-NQR, highlighting the evolution of magnetic fluctuations and the superconducting region near the quantum critical point.

Findings

Antiferromagnetic order suppressed above 1.36 GPa.

Superconductivity observed between 1.36 and 1.84 GPa.

Maximum T_c of about 0.9 K near the quantum critical point.

Abstract

We present a novel phase diagram for the antiferromagnetism and superconductivity in Ce$_2$RhIn$_8$ probed by In-NQR studies under pressure ($P$). The quasi-2D character of antiferromagnetic spin fluctuations in the paramagnetic state at $P$ = 0 evolves into a 3D character because of the suppression of antiferromagnetic order for $P > P_{\rm QCP}\sim$ 1.36 GPa (QCP: antiferromagnetic quantum critical point). Nuclear-spin-lattice-relaxation rate $1/T_1$ measurements revealed that the superconducting order occurs in the $P$ range 1.36 -- 1.84 GPa, with maximum $T_c\sim$ 0.9 K around $P_{\rm QCP}\sim$ 1.36 GPa.