Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · cond-mat/0504034

How chemistry controls electron localization in 3d1 perovskites: A Wannier-function study

E. Pavarini·A. Yamasaki·J. Nuss·O. K. Andersen
View original source ↗Read source document ↗Export metadata ↓

Abstract

In the series of 3d1 t2g perovskites, SrVO3--CaVO3--LaTiO3--YTiO3 the transition-metal d electron becomes increasingly localized and undergoes a Mott transition between CaVO3 and LaTiO3. By defining a low-energy Hubbard Hamiltonian in the basis of Wannier functions for the t2g LDA band and solving it in the single-site DMFT approximation, it was recently shown[1] that simultaneously with the Mott transition there occurs a strong suppression of orbital fluctuations due to splitting of the t2g levels. The present paper reviews and expands this work, in particular in the direction of exposing the underlying chemical mechanisms by means of ab initio LDA Wannier functions generated with the NMTO method. The Wannier functions for the t2g band exhibit covalency between the transition-metal t2g, the large cation-d, and the oxygen-p states; this covalency, which increases along the series, turns out to be responsible not only for the splittings of the t2g levels, but also for non-cubic perturbations of the hopping integrals, both of which are decisive for the Mott transition. We find good agreement with the optical and photoemission spectra, with the crystal-field splittings and orbital polarizations recently measured for the titanates, and with the metallization volume for LaTiO3. The metallization volume for YTiO3 is predicted. Using super-exchange theory, we reproduce the observed magnetic orders in LaTiO3 and YTiO3, but the results are sensitive to detail, in particular for YTiO3 which, without the Jahn-Teller distortion, would be AFM C- or A-type, rather than FM. Finally, we show that it possible to unfold the orthorhombic t2g LDA bandstructure to a pseudocubic zone. In this zone, the lowest band is separated from the two others by a direct gap and has a width, W_I, which is significantly smaller than that, W, of the entire t2g band. The progressive GdFeO3-type distortion favours electron localization by decreasing W, by increasing the splitting of the t2g levels and by decreasing W_I. Our conclusions concerning the roles of GdFeO3-type and JT distortions agree with those of Mochizuki and Imada [2].

Explore related subjects

cond-mat.str-el

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

E. Pavarini, A. Yamasaki, J. Nuss, O. K. Andersen. 2005-10-11. How chemistry controls electron localization in 3d1 perovskites: A Wannier-function study. https://doi.org/10.1088/1367-2630%2F7%2F1%2F188

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

Exotic Spin Excitation Continuum in a Weakly Coupled Quantum Chainsaw Antiferromagnet

Collective motions in strongly interacting magnets involve many spins and are often described in terms of integer-spin excitations. However, in certain cases, the collective motion can behave as if these integer excitations break apart into smaller, particle-like entities with unusual properties. Such fractionalized excitations in quantum magnets are commonly associated either with topological order in two dimensions or with criticality in one dimension. It remains unclear how these distinct mechanisms are connected across a dimensional crossover. Here we investigate the Ti-based quantum antiferromagnet, $Cs_{8}LiNa_{3}Ti_{12}F_{48}$, in which $Ti^{3+}$ ($3d^{1}$, $S=1/2$) ions interact antiferromagnetically within distorted kagome planes. Our inelastic neutron scattering study on a single crystal reveals a frustrated network of weakly coupled spin-$1/2$ chainsaws, realizing a regime of dimensional frustration in which interchain couplings fail to establish coherent two-dimensional order. The magnetic excitation spectrum exhibits a strong continuum spanning the full measured momentum and energy phase space. In addition, the dynamic spin correlation function displays rod-like scattering in momentum space, indicating a quasi-one-dimensional nature of the magnetic correlations. These results point to fractionalized excitations with intrinsically directional character, demonstrating that signatures of one-dimensional criticality can persist within a two-dimensional lattice. Our findings establish anisotropic fractionalization as a distinct organizing principle for quantum-disordered states.

cond-mat.str-el↗
arXiv2026

Unraveling the Kagome Antiferromagnetic $3J$ Model and Its Materials: An Integrated Approach

We investigate the ground-state and finite-temperature properties of the kagome antiferromagnetic Heisenberg model with three inequivalent couplings, dubbed the $3J$ model, which is designed for the candidate Dirac quantum spin liquid (QSL) material YCu$_3$(OH)$_6$Br$_2$[Br$_{1-x}$(OH)$_x$] (see, e.g., Zeng et al., 2024). Employing large-scale density-matrix renormalization group (DMRG) supplemented by neural quantum states (NQS) simulations, we identify an intermediate QSL phase between two magnetically ordered phases. We also find that this QSL is separated from the kagome spin liquid ground state at the isotropic limit. To establish a direct comparison with experiments, we compute the specific heat of the model by means of advanced exponential (XTRG) and tangent-space (tanTRG) thermal tensor-network methods. In the magnetically ordered phase, the specific heat over temperature exhibits a shoulder at a temperature that is a fraction of the coupling strength $J_{h}$, which disappears in the QSL phase. These universal behaviors are consistent with the experimentally observed specific heat in $3J$ materials for both ordered and QSL candidate samples. Our work thus connects microscopic models with experimentally measurable signatures, exemplifying an integrated approach to understanding QSL phenomena in frustrated quantum magnets~ (see Meng et al., 2026), with $3J$ materials serving as a representative case and providing a foundation for future studies.

cond-mat.str-el↗
arXiv2026

Quantum-interference-driven orbital density wave and high-temperature superconductivity in trilayer nickelates

Intertwined charge-density-wave (CDW) and spin-density-wave (SDW) orders are a hallmark of high-temperature superconducting multilayer nickelates. In trilayer La4Ni3O_{10}, charge correlations develop at temperatures above the onset of long-range spin order, and the characteristic ordering wavevectors satisfy $Q_{cdw} \approx 2Q_{sdw}$. Here, using a density-wave equation with vertex corrections, we show that quantum interference between short-range SDW fluctuations at $q \approx Q_{sdw}$ on the outer NiO2 layers generates an inter-outer-layer bond order at $Q_{cdw} \approx 2 Q_{sdw}$. This bond order induces a pronounced inner-layer-centered orbital order, with antiphase modulations of the Ni $d_{3z^2-r^2}$ and $d_{x^2-y^2}$ occupations, producing strong orbital polarization but only weak total charge modulation. This intertwined bond-and-orbital order accounts for the layer-selective electronic reconstruction inferred from NMR/NQR and is consistent with Raman spectroscopy and scanning tunnelling microscopy measurements. The same orbital and spin fluctuations also cooperate to stabilize $s_{\pm}$-wave superconductivity through $M_z$ mirror-parity selection rules. Our results provide a unified microscopic framework for intertwined density-wave order and high-Tc superconductivity in multilayer nickelates.

cond-mat.str-el↗