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Title: Block excitonic condensate at n = 3.5 in a spin-orbit coupled t 2 g multiorbital Hubbard model

Abstract

Theoretical studies recently predicted the condensation of spin-orbit excitons at momentum $$q={\pi}$$ in $${t}_{2g}^{4}$$ spin-orbit coupled three-orbital Hubbard models at electronic density $n=4$. In parallel, experiments involving iridates with noninteger valence states for the Ir ions are starting to attract considerable attention. Using the density matrix renormalization group technique we present evidence for the existence of an excitonic condensate at $n=3.5$ in a one-dimensional Hubbard model with a degenerate $${t}_{2g}$$ sector, when in the presence of spin-orbit coupling. At intermediate Hubbard $U$ and spin-orbit $${\lambda}$$ couplings, we found an excitonic condensate at the unexpected momentum $$q={\pi}/2$$ involving $${j}_{\mathrm{eff}}=3/2,m=\pm{}1/2$$, and $${j}_{\mathrm{eff}}=1/2,m=\pm{}1/2$$ bands in the triplet channel, coexisting with an also unexpected block magnetic order. We also present the entire $${\lambda}$$ vs $U$ phase diagram, at a fixed and robust Hund coupling. Interestingly, this new “block excitonic phase” is present even at large values of $${\lambda}$$, unlike the $n=4$ excitonic phase discussed before. Our computational study helps to understand and predict the possible magnetic phases of materials with $${d}^{3.5}$$ valence and robust spin-orbit coupling.

Authors:
 [1];  [2];  [3];  [1];  [1]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division; Univ. of British Columbia, Vancouver, BC (Canada). Quantum Matter Inst.
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Sciences. Computational Science and Engineering Division
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
OSTI Identifier:
1542205
Alternate Identifier(s):
OSTI ID: 1505667
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 99; Journal Issue: 15; Journal ID: ISSN 2469-9950
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English

Citation Formats

Kaushal, Nitin, Nocera, Alberto, Alvarez, Gonzalo, Moreo, Adriana, and Dagotto, Elbio. Block excitonic condensate at n=3.5 in a spin-orbit coupled t2g multiorbital Hubbard model. United States: N. p., 2019. Web. doi:10.1103/PhysRevB.99.155115.
Kaushal, Nitin, Nocera, Alberto, Alvarez, Gonzalo, Moreo, Adriana, & Dagotto, Elbio. Block excitonic condensate at n=3.5 in a spin-orbit coupled t2g multiorbital Hubbard model. United States. doi:10.1103/PhysRevB.99.155115.
Kaushal, Nitin, Nocera, Alberto, Alvarez, Gonzalo, Moreo, Adriana, and Dagotto, Elbio. Mon . "Block excitonic condensate at n=3.5 in a spin-orbit coupled t2g multiorbital Hubbard model". United States. doi:10.1103/PhysRevB.99.155115.
@article{osti_1542205,
title = {Block excitonic condensate at n=3.5 in a spin-orbit coupled t2g multiorbital Hubbard model},
author = {Kaushal, Nitin and Nocera, Alberto and Alvarez, Gonzalo and Moreo, Adriana and Dagotto, Elbio},
abstractNote = {Theoretical studies recently predicted the condensation of spin-orbit excitons at momentum $q={\pi}$ in ${t}_{2g}^{4}$ spin-orbit coupled three-orbital Hubbard models at electronic density $n=4$. In parallel, experiments involving iridates with noninteger valence states for the Ir ions are starting to attract considerable attention. Using the density matrix renormalization group technique we present evidence for the existence of an excitonic condensate at $n=3.5$ in a one-dimensional Hubbard model with a degenerate ${t}_{2g}$ sector, when in the presence of spin-orbit coupling. At intermediate Hubbard $U$ and spin-orbit ${\lambda}$ couplings, we found an excitonic condensate at the unexpected momentum $q={\pi}/2$ involving ${j}_{\mathrm{eff}}=3/2,m=\pm{}1/2$, and ${j}_{\mathrm{eff}}=1/2,m=\pm{}1/2$ bands in the triplet channel, coexisting with an also unexpected block magnetic order. We also present the entire ${\lambda}$ vs $U$ phase diagram, at a fixed and robust Hund coupling. Interestingly, this new “block excitonic phase” is present even at large values of ${\lambda}$, unlike the $n=4$ excitonic phase discussed before. Our computational study helps to understand and predict the possible magnetic phases of materials with ${d}^{3.5}$ valence and robust spin-orbit coupling.},
doi = {10.1103/PhysRevB.99.155115},
journal = {Physical Review B},
number = 15,
volume = 99,
place = {United States},
year = {2019},
month = {4}
}

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Works referenced in this record:

Engineering 1D Quantum Stripes from Superlattices of 2D Layered Materials
journal, October 2016

  • Gruenewald, John H.; Kim, Jungho; Kim, Heung Sik
  • Advanced Materials, Vol. 29, Issue 1, Article No. 1603798
  • DOI: 10.1002/adma.201603798