%0 Journal Article %1 PhysRevB.105.214411 %A Liu, Huimei %A Chaloupka, Jiří %A Khaliullin, Giniyat %D 2022 %I American Physical Society %J Phys. Rev. B %K a %N 21 %P 214411 %R 10.1103/PhysRevB.105.214411 %T Exchange interactions in d$^5$ Kitaev materials: from Na$_2$IrO$_3$ to α-RuCl$_3$ %U https://link.aps.org/doi/10.1103/PhysRevB.105.214411 %V 105 %X We present an analytical study of the exchange interactions between pseudospin one-half d5 ions in honeycomb lattices with edge-shared octahedra. Various exchange channels involving Hubbard U, charge-transfer excitations, and cyclic exchange are considered. Hoppings within t2g orbitals as well as between t2g and eg orbitals are included. Special attention is paid to the trigonal crystal field effects on the exchange parameters. The obtained exchange Hamiltonian is dominated by ferromagnetic Kitaev interaction K within a wide range of. It is found that a parameter region close to the charge-transfer insulator regime and with a small is most promising to realize the Kitaev spin liquid phase. Two representative honeycomb materials Na2IrO3 and α-RuCl3 are discussed based on our theory. We have found that both materials share dominant ferromagnetic K and positive nondiagonal  values. However, their Heisenberg J terms have opposite signs: AFM J > 0 in Na2IrO3 and FM J < 0 in α-RuCl3. This brings different magnetic fluctuations and results in their different magnetization behaviors and spin excitation spectra. Proximity to FM state due to the large FM J is emphasized in α-RuCl3. The differences between the exchange couplings of these two materials originate from the opposite values, indicating that the crystal field can serve as an efficient control parameter to tune the magnetic properties of d5 spin-orbit Mott insulators.

@article{PhysRevB.105.214411, abstract = {We present an analytical study of the exchange interactions between pseudospin one-half d5 ions in honeycomb lattices with edge-shared octahedra. Various exchange channels involving Hubbard U, charge-transfer excitations, and cyclic exchange are considered. Hoppings within t2g orbitals as well as between t2g and eg orbitals are included. Special attention is paid to the trigonal crystal field effects on the exchange parameters. The obtained exchange Hamiltonian is dominated by ferromagnetic Kitaev interaction K within a wide range of. It is found that a parameter region close to the charge-transfer insulator regime and with a small is most promising to realize the Kitaev spin liquid phase. Two representative honeycomb materials Na2IrO3 and α-RuCl3 are discussed based on our theory. We have found that both materials share dominant ferromagnetic K and positive nondiagonal  values. However, their Heisenberg J terms have opposite signs: AFM J > 0 in Na2IrO3 and FM J < 0 in α-RuCl3. This brings different magnetic fluctuations and results in their different magnetization behaviors and spin excitation spectra. Proximity to FM state due to the large FM J is emphasized in α-RuCl3. The differences between the exchange couplings of these two materials originate from the opposite values, indicating that the crystal field can serve as an efficient control parameter to tune the magnetic properties of d5 spin-orbit Mott insulators.}, added-at = {2023-05-31T12:51:55.000+0200}, author = {Liu, Huimei and Chaloupka, Jiří and Khaliullin, Giniyat}, biburl = {https://www.bibsonomy.org/bibtex/2b971043be2c879d5c4d49f9e0ce00600/ctqmat}, day = 08, description = {Exchange interactions in d5 Kitaev materials: from Na2IrO3 to α-RuCl3}, doi = {10.1103/PhysRevB.105.214411}, interhash = {e7f30eb47507aeaffa7c9ea78e258499}, intrahash = {b971043be2c879d5c4d49f9e0ce00600}, journal = {Phys. Rev. B}, keywords = {a}, month = {06}, number = 21, numpages = {12}, pages = 214411, publisher = {American Physical Society}, timestamp = {2023-10-19T13:58:08.000+0200}, title = {Exchange interactions in d$^{\mathbf{5}}$ Kitaev materials: from Na$_{\mathbf{2}}$IrO$_{\mathbf{3}}$ to α-RuCl$_{\mathbf{3}}$}, url = {https://link.aps.org/doi/10.1103/PhysRevB.105.214411}, volume = 105, year = 2022 }