DFT+DMFT study of spin-charge-lattice coupling in covalent LaCoO${}_3$

Abstract

We study energetics and the nature of both homogeneous and mixed spin (MS) states in LaCoO${}_3$ incorporating structural changes of the crystal volume expansion and the Co-O bond disproportionation (BD) during the spin-state transition using the density functional theory plus dynamical mean field theory (DFT+DMFT) method. DFT+DMFT predicts that energetics of both excited spin states are almost the same while DFT+U calculations of the same structures energetically favor the MS states and produce various metastable solutions whose energetics depend sensitively on final spin states. Within DFT+DMFT, the homogeneous spin state in the expanded crystal volume shows the multiconfigurational nature with non-negligible occupancy probabilities of both high spin (HS) and low spin (LS) states along with $d^6$ and $d^7$ charge configurations indicating the dynamically fluctuating nature of spin and charge states due to the Co-O covalency. The nature of the MS state under the BD structure reveals that Co sites with the long Co-O bonds develop a Mott insulating state and favor HS with a $d^6$ configuration, while more covalent Co sites with the short Co-O bonds occupy more LS states with a $d^7$ configuration and behave as a band insulator, as a result, charge ordering is induced in the BD structure from the spin-state ordering. We also find that both energetics and electronic structure sensitively depend on the Co-O covalency effect, which can be tuned by changing the double counting potential and the resulting $d-$occupancy ($N_d$), and $N_d$ close to 6.7 is consistent with the nature of the spin-state transition. Our results show that structural changes during the spin-state transition can play an important role in understanding energetics and electronic structure of LaCoO${}_3$.

arXiv comment13 pages, 11 figures

References in corpus (23)

• Maximally localized Wannier functions: Theory and applications
• Electronic Structure Calculations with Dynamical Mean-Field Theory: A Spectral Density Functional Approach
• Continuous-time Monte Carlo methods for quantum impurity models
• Quantum Monte Carlo Impurity Solver for Cluster DMFT and Electronic Structure Calculations in Adjustable Base
• The spin state transition in LaCoO${}_3$; revising a revision
• Structural phenomena associated with the spin-state transition in LaCoO3
• Evidence for a Low-Spin to Intermediate-Spin State Transition in LaCoO3
• Site-selective Mott transition in rare earth nickelates
• Exact double-counting in combining the Dynamical Mean Field Theory and the Density Functional Theory
• Spin-state transition in LaCoO3: direct neutron spectroscopic evidence of excited magnetic states
• Strain-Induced Spin States in Atomically Ordered Cobaltites
• Structural anomalies associated with the electronic and spin transitions in LnCoO3
• Total energy calculations using DFT+DMFT: computing the pressure phase diagram of the rare earth nickelates
• Spin state transition and covalent bonding in LaCoO3
• Computing total energies in complex materials using charge self-consistent DFT+DMFT
• Disproportionation and Metallization at Low-Spin to High-Spin Transition in Multiorbital Mott Systems
• Covalency in transition metal oxides within all-electron Dynamical Mean Field Theory
• Covalency, double-counting and the metal-insulator phase diagram in transition metal oxides
• Anomalous expansion and phonon damping due to the Co spin-state transition in RCoO_3 with R = La, Pr, Nd and Eu
• Importance of exchange-anisotropy and superexchange for the spin-state transitions in LnCoO3 (Ln=La,Y,RE) cobaltates
• Covalency and the metal-insulator transition in titanate and vanadate perovskites
• Role of Entropy and Structural Parameters in the Spin State Transition of LaCoO${}_3$
• Low temperature mixed spin state of Co3+ in LaCoO3 evidenced from Jahn-Teller lattice distortions

Cited by in corpus (10)

• DMFTwDFT: An open-source code combining Dynamical Mean Field Theory with various Density Functional Theory packages
• Oxygen vacancy induced site-selective mott transition in lanio3
• Origin of the orbital polarization of Co${}^{2+}$ in La${}_2$CoTiO${}_6$ and (LaCoO${}_3$)${}_1$+(LaTiO${}_3$)${}_1$ : a DFT+$U$ and DMFT study
• Effect of Off-Diagonal Elements in Wannier Hamiltonian on DFT+DMFT for low-symmetry material: Study of Li${}_2$MnO${}_3$
• Delocalized polaron and Burstein-Moss shift induced by Li in $\alpha$-${\text{V}}_2{\text{O}}_5$: DFT+DMFT study
• Symmetry-resolved elastic anomalies in spin-crossover cobaltite LaCoO${}_3$
• Real-space charge distribution of the cobalt ion and its relation with charge and spin states
• First-principle Study of Multiple Metastable Charge Ordering States in La${}_{1/3}$Sr${}_{2/3}$FeO${}_3$
• Stability and diffusion of oxygen vacancies in LaNiO${}_3$: a DMFT study
• Weak electronic correlations in the cobalt oxychalcogenide superconductor Na2CoSe2O