Coexistence of zigzag antiferromagnetic order and superconductivity in compressed NiPSe3

NiPSe3 is regarded as a bandwidth-controlled Mott insulator, distinct from the widely studied Mott insulating magnetic graphene MPSe3 (M = Mn and Fe) family. By employing high-pressure synchrotron X-ray diffraction, we observe two structural transitions as a function of pressure. With the help of first-principles calculations, we discover the antiferromagnetic (AFM) moment directions of NiPSe3 switch from out-of-plane to in-plane and the honeycomb layers slide relative to each other at the first structural transition. The in-plane AFM order persists until the second structural transition, whereupon the two-dimensional (2D) structure assumes a more three-dimensional (3D) character. A bandwidth-controlled Mott insulator-metal transition (IMT) occurs between the two structural transitions at Pc -8.0 GPa, concomitant with the emergence of superconductivity with Tc -4.8 K. The superconductivity in NiPSe3 emerging in the 2D monoclinic phase coexists with the in-plane AFM order and continues into the 3D trigonal phase. Our electronic structure calculations reveal that the IMT and supercon-ductivity in NiPSe3 are both related to the enhanced Se2-4p and Ni2+ 3d electronic hybridizations under pressure. From these results, we construct a temperature-pressure electronic phase diagram of NiPSe3, revealing interesting relationships between magnetism and superconductivity.

Automated summary

Through high-pressure synchrotron X-ray diffraction, two structural transitions are observed in NiPSe3 as a function of pressure, with the antiferromagnetic moment directions changing and the honeycomb layers sliding relative to each other. An insulator-metal transition accompanied by the emergence of superconductivity occurs between the two structural transitions. Electronic structure calculations reveal that these transitions and superconductivity in NiPSe3 are related to the enhanced electronic hybridizations under pressure.