Effect of pressure on the noncentrosymmetric antiferromagnet CeNiC2

Recently, the pressure-induced superconductivity in the CeNiC2 polycrystal has been discovered at 3.5 K around 11 GPa, the highest superconducting transition temperature in a Ce-based heavy-Fermion compound [1]. The intermetallic CeNiC2 crystalizes in orthorhombic structure (space group Amm2) where the lattice lacks the inversion symmetry along c-axis. With decreasing temperature CeNiC2 displays multiple magnetic transitions, an incommensurate antiferromagnetic (iAFM) order at TN1 = 20 K followed by a commensurate AFM order at TN2 = 10 K and a ferromagnetic order at TC = 2 K [2]. In this talk, I will present the pressure phase diagram of CeNiC2 single crystal based on our recent pressure dependence of transport and magnetic data. We observed superconductivity in a narrow pressure range in the vicinity of the vanishing point of TN1. The remarkable coincidence of non-Fermi liquid behavior and the optimal , coupled with moreover, the non-centrosymmetric crystal structure suggest that superconductivity in CeNiC2 is unconventional and exotic in nature.
References
[1] S. Katano et al., Phys. Rev. B 99, 100501(R) (2019).
[2] V. K. Pecharsky et al., Phys. Rev. B 58, 497 (1998).