  Engineering magnetism in layered magnets could result in novel phenomena
related to two-dimensional (2D) magnetism, which can be useful for fundamental
research and practical applications. Extensive doping efforts such as
substitution and intercalation have been adopted to tune antiferromagnetic
(AFM) properties in M2P2X6 compounds. The substitutional doping in this
material family has mainly focused on bimetallic substitution. Recently, the
metal substitution can also be extended to more than two metal elements,
leading to medium and high-entropy alloys (MEAs and HEAs), which are fairly
underexplored in layered magnetic systems including M2P2X6. In this work, we
explored the magnetic properties of the previously unreported Cu- and
Cr-substituted Ni2P2S6 i.e., CuxNi2(1-x)CrxP2S6. Our study reveals a relatively
systematic evolution of AFM phases with substitution than that observed in
traditional bimetallic substitution in M2P2X6. Furthermore, the Cu and Cr
substitutions in Ni2P2S6 are found to enhance the ferromagnetic (FM)
correlation, which is also accompanied by a possible weak FM phase at low
temperatures for the intermediate compositions from 0.32 to 0.80. Our work
provides a strategy to establish ferromagnetism in AFM M2P2X6 that can also be
used for property tuning in other layered magnets.
