Charge–spin–orbital states in the tri-layered nickelate La₄Ni₃O₈: an ab initio study

Abstract

The electronic and magnetic structures of La 4 Ni 3 O 8 , an analogue of the hole doped cuprates, are studied using the configuration state constrained local-spin-density approximation plus Hubbard U calculations. It is found to be a C-type antiferromagnetic Mott insulator, in which an orbital hybridization strongly reduces an otherwise possible charge disproportionation. This state accounts for several experimental observations. The involved Ni 2+ high-spin state and its orbital configuration are found to be against a crystal-field level picture, which predicts an Ni 2+ low-spin state in the NiO 2 square lattice. We note, however, that La 4 Ni 3 O 8 , if in the low-spin state, would be a chargehomogeneous ferromagnetic half-metal with only the up-spin x 2 -y 2 conduction band. Therefore, low-spin nickelates may be explored for any interesting property.

Charge ordering inNi1+/Ni2+nickelates:La4Botana1, Pardo2, Pickett3 et al. 2016Phys. Rev. B554461View full textAdd to dashboardCite

“…but this has been shown to be very unfavorable in energy 20 . If all the Ni ions have the same valence, the e g states, with 2.67 electrons per Ni on average can occur in two different ways: the LS state and the HS state that give rise to a metallic and an insulating state, respectively (Fig.…”

Dimensionality-induced insulator-metal crossover in layered nickelates Lan+1NinO2n+2 (n = 2, 3, and ∞)

“…7 Moreover, the dimensionality-induced IMT occurs in bulk Ruddlesden-Popper series Sr n+1 Ir n O 3n+1 (n = 1, 2, and ∞). 8 The bulk T -type nickelates La n+1 Ni n O 2n+2 (n = 2, 3, and ∞) [9][10][11][12][13][14][15][16][17][18][19][20][21] with infinite NiO 2 square planes seem to be another candidate for the dimensionality-controlled IMT. They contain bilayer, trilayer and infinite-layer of NiO 2 planes for La 3 Ni 2 O 6 (n = 2), La 4 Ni 3 O 8 (n = 3) and LaNiO 2 (n = ∞), respectively, as shown in Fig.…”

“…Poltavets et al 10 and Liu et al 19 found a molecular correlated insulating ground state, which is similar to a partially charge-disproportioned insulating state proposed by Wu. 20 Anisimov et al 18 reported that LaNiO 2 is an AFM insulator similar to CaCuO 2 (Ref. 22), but it was suggested to be nonmagnetic (NM) and probably metal by Lee and Pickett.…”

Magnon dressing by orbital excitations in ferromagnetic planes of K2CuF4 and LaMnO3

“…In their pioneering work Kugel and Khomskii [2] have shown that when degenerate orbitals are partly filled, spin-orbital superexchange couples spin and orbital degrees of freedom. It leads to phases with spin-orbital superexchange in two-dimensional (2D) [3][4][5][6][7][8] or in three-dimensional (3D) [9][10][11][12][13][14][15][16][17][18][19][20] systems. When both spin and orbital degrees of freedom are active joint spin-orbital quantum fluctuations arise and may even destabilize long-range order [21].…”