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

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 $P>P_{\mathrm{Q}\mathrm{C}\mathrm{P}}\sim$ 1.36 GPa (QCP: antiferromagnetic quantum critical point). Nuclear-spin-lattice-relaxation rate $1\mathrm{/}{T}_1$ 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 $P_{\mathrm{Q}\mathrm{C}\mathrm{P}}\sim$ 1.36 GPa.