TY - JOUR

T1 - Ab initio derivation of low-energy Hamiltonians for systems with strong spin-orbit interaction

T2 - Application to Ca5 Ir3 O12

AU - Charlebois, Maxime

AU - Morée, Jean Baptiste

AU - Nakamura, Kazuma

AU - Nomura, Yusuke

AU - Tadano, Terumasa

AU - Yoshimoto, Yoshihide

AU - Yamaji, Youhei

AU - Hasegawa, Takumi

AU - Matsuhira, Kazuyuki

AU - Imada, Masatoshi

N1 - Funding Information:
This work was supported by Fonds de recherche du Québec—Nature et technologies (FRQNT). We also acknowledge the financial support of JSPS Kakenhi Grants No. 16H06345 (M.C., J.M., K.N., Y.N., T.T., Y.Y., Y.Y., and M.I.), No. 17K14336 (Y.N.), No. 18H01158 (Y.N.), No. 20K14423 (Y.N.), No. 16K05452 (K.N.), No. 17H03393 (K.N.), No. 17H03379 (K.N.), and No. 19K03673 (K.N.). The authors are grateful to the MEXT HPCI Strategic Programs, and the Creation of New Functional Devices and High-Performance Materials to Support Next Generation Industries (CDMSI), for their financial support. This work was supported by MEXT as a “Program for Promoting Research on the Supercomputer Fugaku” (Basic Science for Emergence and Functionality in Quantum Matter). We also acknowledge the support provided by the RIKEN Advanced Institute for Computational Science under the HPCI System Research project (Grants No. hp180170, No. hp190145, and No. hp200132). Part of the computation was done at Supercomputer Center, Institute for Solid State Physics, University of Tokyo. Also, another part of the computation was done by using the supercomputer system at the information initiative center, Hokkaido University, Sapporo, Japan.
Publisher Copyright:
© 2021 American Physical Society.

PY - 2021/8/15

Y1 - 2021/8/15

N2 - We present an ab initio derivation method for effective low-energy Hamiltonians of material with strong spin-orbit interactions. The effective Hamiltonian is described in terms of the Wannier function in the spinor form, and effective interactions are derived with the constrained random phase approximation (cRPA) method. Based on this formalism and the developed code, we derive an effective Hamiltonian of a strong spin-orbit interaction material Ca5Ir3O12. This system consists of three edge-shared IrO6 octahedral chains arranged along the c axis, and the three Ir atoms in the ab plane compose a triangular lattice. For such a complicated structure, we need to set up the Wannier spinor function under the local coordinate system. We found that a density-functional band structure near the Fermi level is formed by local dxy and dyz orbitals. Then, we constructed the ab initio dxy/dyz model. The estimated nearest-neighbor transfer t is close to 0.2 eV, and the cRPA on-site U and neighboring V electronic interactions are found to be 2.4-2.5 eV and 1 eV, respectively. The resulting characteristic correlation strength defined by (U-V)/t is above 7, and thus this material is classified as a strongly correlated electron system. The on-site transfer integral involved in the spin-orbit interaction is 0.2 eV, which is comparable to the on-site exchange integrals ∼0.2 eV, indicating that the spin-orbit-interaction physics would compete with the Hund physics. Based on these calculated results, we discuss possible rich ground-state low-energy electronic structures of spin, charge, and orbitals with competing Hund, spin-orbit, and strong-correlation physics.

AB - We present an ab initio derivation method for effective low-energy Hamiltonians of material with strong spin-orbit interactions. The effective Hamiltonian is described in terms of the Wannier function in the spinor form, and effective interactions are derived with the constrained random phase approximation (cRPA) method. Based on this formalism and the developed code, we derive an effective Hamiltonian of a strong spin-orbit interaction material Ca5Ir3O12. This system consists of three edge-shared IrO6 octahedral chains arranged along the c axis, and the three Ir atoms in the ab plane compose a triangular lattice. For such a complicated structure, we need to set up the Wannier spinor function under the local coordinate system. We found that a density-functional band structure near the Fermi level is formed by local dxy and dyz orbitals. Then, we constructed the ab initio dxy/dyz model. The estimated nearest-neighbor transfer t is close to 0.2 eV, and the cRPA on-site U and neighboring V electronic interactions are found to be 2.4-2.5 eV and 1 eV, respectively. The resulting characteristic correlation strength defined by (U-V)/t is above 7, and thus this material is classified as a strongly correlated electron system. The on-site transfer integral involved in the spin-orbit interaction is 0.2 eV, which is comparable to the on-site exchange integrals ∼0.2 eV, indicating that the spin-orbit-interaction physics would compete with the Hund physics. Based on these calculated results, we discuss possible rich ground-state low-energy electronic structures of spin, charge, and orbitals with competing Hund, spin-orbit, and strong-correlation physics.

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U2 - 10.1103/PhysRevB.104.075153

DO - 10.1103/PhysRevB.104.075153

M3 - Article

AN - SCOPUS:85114043667

VL - 104

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 2469-9950

IS - 7

M1 - 075153

ER -