Limited Ferromagnetic Interactions in Monolayers of MPS₃ (M = Mn and Ni)

Abstract

We present a systematic study of the electronic and magnetic properties of two-dimensional ordered alloys, consisting of two representative hosts (MnPS 3 and NiPS 3 ) of transition metal phosphorus trichalcogenides doped with 3d elements. For both hosts, our DFT + U calculations are able to qualitatively reproduce the ratios and signs of all experimentally observed magnetic couplings. The relative strength of all antiferromagnetic exchange couplings, both in MnPS 3 and in NiPS 3 , can successfully be explained using an effective direct exchange model: it reveals that the third-neighbor exchange dominates in NiPS 3 due to the filling of the t 2g subshell, whereas for MnPS 3 , the first-neighbor exchange prevails, owing to the presence of the t 2g magnetism. On the other hand, the nearest neighbor ferromagnetic coupling in NiPS 3 can only be explained using a more complex superexchange model and is (also) largely triggered by the absence of the t 2g magnetism. For the doped systems, the DFT + U calculations revealed that magnetic impurities do not affect the magnetic ordering observed in the pure phases, and thus, in general in these systems, ferromagnetism may not be easily induced by such a kind of elemental doping. However, unlike for the hosts, the first and second (dopant–host) exchange couplings are of similar order of magnitude. This leads to frustration in the case of antiferromagnetic coupling and may be one of the reasons of the observed lower magnetic ordering temperature of the doped systems.

Dual Character of the Insulating State in the van der Waals Fe1–xNixPS3 Alloyed Compounds

“…Analysis of the relative stabilities of different structural arrangements (Figures b–d and S1c–e) leads to the conclusion that metal atoms of the same kind have tendency to cluster. The similar effect for Ni was previously observed when studying Mn 0.75 Ni 0.25 PS 3 …”

“…The similar effect for Ni was previously observed when studying Mn 0.75 Ni 0.25 PS 3 . 51 All systems under study are semiconductors with band gaps (E g ) ranging from 2.45 to 2.87 eV. The limiting values were found for x = 0, i.e., pristine FePS 3 , and x = 1, i.e., pristine NiPS 3 .…”

Variation between Antiferromagnetism and Ferrimagnetism in NiPS3 by Electron Doping

“…According to the energy differences between the four different magnetic orders, we extract the nearest-neighbor (J 1 ), second-nearest-neighbor (J 2 ), and third-nearest-neighbor (J 3 ) coupling constants (details for calculation in Supporting Information): J 1 = −2.50 meV, J 2 = −0.26 meV, and J 3 = 12.90 meV, which are consistent with previous results. [33,[52][53][54] Among the three magnetic exchange coupling parameters, J 3 >> J 1 >> J 2 . J 3 is strongly AFM stemming from super-exchange interactions and is the dominant exchange coupling.…”

Correlation-Driven Topological Transition in Janus Two-Dimensional Vanadates

“…Since the observation of intrinsic ferromagnetism in two-dimensional layered materials (2D) such as CrGeTe 3 [ 1 ] and CrI 3 [ 2 ], the fields of magnetism and spintronics have received tremendous research attention in the 2D limit [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The atomically thin 2D magnetic materials are considered ideal systems, where the magnetic and spin-related features can effectively be controlled and modulated via proximity effects, electric field, magnetic field, strain, defects and optical doping [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ].…”