Spin-moment formation and reduced orbital polarization in LaNiO3/LaAlO3superlattice:LDA+U

Abstract

Density functional band calculations have been performed to study LaNiO3/LaAlO3 superlattices. Motivated by recent experiments reporting the magnetic and metal-insulator phase transition as a function of LaNiO3 layer thickness, we examined the electronic structure, magnetic properties, and orbital occupation depending on the number of LaNiO3 layers. Calculations show that the magnetic phase is stabler than the nonmagnetic for finite and positive U values. The orbital polarization is significantly reduced by U even in the magnetic regions. The implications of the results are discussed in comparison to recent experimental and theoretical studies within the limitations of the LDA+U method.PACS numbers: 71.15.Mb

Confinement-driven transitions between topological and Mott phases in(LaNiO3)N/(LaAlDoennig1, Pickett2, Pentcheva3 2014Phys. Rev. B676870View full textAdd to dashboardCite

“…2, top). Unlike the initial prediction of Chaloupka and Khaliullin 7 , only a weak orbital polarization was reported so far for (001)-oriented LNO superlattices [10][11][12]30 . Most recent experiments suggest exclusively positive values of P = (n x 2 −y 2 − n 3z 2 −r 2 )/(n x 2 −y 2 + n 3z 2 −r 2 ), e.g.…”

Effect of charge doping on the electronic structure, orbital polarization, and structural distortion in nickelate superlattice

“…ii) In the small-U eff ( < ∼ 2 eV) regime the paramagnetic or weak ferromagnetic metal phase is stable, while the 'half-metallic' ferromagnetic phase with gapless majority and gapped minority spin channel is stabilized when U eff is large ( > ∼ 4 eV). The preference for the ferromagnetic phase is consistent with a previous DFT+U study in these regimes 24,25,29 , although these results are not well compared with the recent experimental observations that report the insulating phase with no magnetization in ultrathin LaNiO 3 heterostructures 21,22 . iii) In between the weak and strong U eff regime (U eff 3 eV), the metallic phase with antiferromagnetic order (ferrimagnetic order in the fully distorted calculations) is preferred over the ferromagnetic states.…”

“…iii) In between the weak and strong U eff regime (U eff 3 eV), the metallic phase with antiferromagnetic order (ferrimagnetic order in the fully distorted calculations) is preferred over the ferromagnetic states. The antiferromagnetic phases in the tetrogonally distorted cells were not captured by the previous DFT+U study, in which sparse sets of U eff values were used 24,29 . The antiferromagnetic phase turns into ferrimagnetic phases in the fully distorted calculations.…”

“…Indeed, it has recently been reported that LaNiO 3 , which is a paramagnetic metal in the bulk phase, shows insulating behavior with magnetic order in a superlattice 21,22 . There have been a number of subsequent studies about nickelate heterostructures [22][23][24][25][26][27][28][29][30][31][32][33] , which show a potential for rich physics, but there has not been systematic studies about the effect of doping in these systems yet.…”

Fermi level density of states modulation without charge transfer in nickelate superlattices

“…It should be noted that (LNO) m /(STO) n is distinctive from the widely-studied systems such as LNO/LAO and LNO film [12,13,14,15,16,17,18,19] [20]. This kind of charge transfer is known to play an important role in determining the magnetic property of LNO/LaMnO 3 (LMO) [21,22,23,24].…”