Ni-based transition metal trichalcogenide monolayer: A strongly correlated quadruple-layer graphene

Abstract

We investigate the electronic physics of layered Ni-based trichalcogenide NiPX3 (X=S, Se), a member of transition-metal trichalcogenides (TMTs) with the chemical formula, ABX3. These Ni-based TMTs distinguish themselves from other TMTs as their low energy electronic physics can be effectively described by the two eg d-orbitals. The major band kinematics is characterized by the unusal long-range effective hopping between two third nearest-neighbor (TNN) Ni sites in the two-dimensional Ni honeycomb lattice so that the Ni lattice can be equivalently viewed as four weakly coupled honeycomb sublattices. Within each sublattice, the electronic physics is described by a strongly correlated two-orbital graphene-type model that results in an antiferromagnetic (AFM) ground state near half filling. We show that the low energy physics in a paramagnetic state is determined by the eight Dirac cones which locate at K, K , K 2 and K 2 points in the first Brillouin zone with a strong AFM fluctuation between two K(K ) and K 2 ( K 2 ) Dirac cones and carrier doping can sufficiently suppress the long-range AFM order and allow other competing orders, such as superconductivity, to emerge. The material can be an ideal system to study many exotic phenomena emerged from strong electron-electron correlation, including a potential d ± id superconducting state at high temperature.arXiv:1811.02333v1 [cond-mat.str-el]

Evidence for biquadratic exchange in the quasi-two-dimensional antiferromagnet FePS3

“…However, the degree of the structural distortion would seem to be far too small to result in a difference of %1 meV observed in Table I. The assumption is supported by ab initio calculations 22,23 which calculated magnetic exchange parameters for energetically relaxed structures. Consistent with observations, the calculated structures were only very slightly distorted and the calculations gave unique exchange parameters for nominally equivalent nearestneighbors which, depending on the magnitude of the on-site repulsion term, were comparable to those of Lançon et al…”

Defect-mediated ferromagnetism in correlated two-dimensional transition metal phosphorus trisulfides

“…Among magnetic MPX 3 , NiPS 3 particularly exhibits intriguing quantum properties owing to the presence of strong charge-spin correlation effects ( 15 , 22 , 26 , 27 ). It shows zigzag antiferromagnetism with weak in-plane anisotropy below T N ~155 K, in which ferromagnetically arranged spin chains are antiferromagnetically coupled throughout the crystal lattice down to bilayer stacking.…”

“…Low-temperature optical conductivity measurements revealed that these intersite transitions are allowed only between AFM Ni neighbors and demonstrated strong correlation between electronic and magnetic structures in NiPS 3 ( 22 ). Notably, NiPS 3 is the only known magnetic vdW material that exhibits NCT ground state with a close resemblance to the hole-doped high-temperature cuprate superconductors ( 27 ).…”

Unconventional high temperature superconductivity in cubic zinc-blende transition metal compounds

“…Under the slave boson mean-field approach, we study superconducting pairings in the hole doped three-orbital model. Due to the high degeneracy of the three t 2g orbitals, the carrier occupancies in the three orbitals are identical, leading to an equal renormalization factor for all the hopping interactions [32]. The results are reported in Fig.4.…”

“…We use the slave boson mean-field approach [20,[30][31][32]] to calculate the superconducting states in the hole doped region. The results are reported in Fig.2 with J/t = 0.3 in (a,b) and J/t = 0.5 in (c,d), respectively.…”