Strong antiferromagnetic interaction owing to a large trigonal distortion in the spin-orbit-coupled honeycomb lattice iridate CdIrO$_3$

Evolution of Magnetism in Single-Crystal Honeycomb Iridates

We report the successful synthesis of single-crystals of the layered iridate, (Na$_{1-x}$Li$_{x}$)$_2$IrO$_3$, $0\leq x \leq 0.9$, and a thorough study of its structural, magnetic, thermal and transport properties. The new compound allows a controlled interpolation between Na$_2$IrO$_3$ and Li$_2$IrO$_3$, while maintaing the novel quantum magnetism of the honeycomb Ir$^{4+}$ planes. The measured phase diagram demonstrates a dramatic suppression of the Néel temperature, $T_N$, at intermediate $x$ suggesting that the magnetic order in Na$_2$IrO$_3$ and Li$_2$IrO$_3$ are distinct, and that at $x\…

Evidences for the random singlet phase in a new honeycomb iridate SrIr$_2$O$_{6-δ}$

Strong spin-orbital-coupling magnetic systems with the honeycomb structure can provide bond-directional interactions which may result in Kitaev quantum spin liquids and exotic anyonic excitations. However, one of the key ingredients in real materials$-$disorders$-$has been much less studied in Kitaev systems. Here we synthesized a trigonal SrIr$_2$O$_{6-δ}$ with $δ\approx 0.25$, which consists of two-dimensional honeycomb Ir planes with edge-sharing IrO$_6$ octahedra. First-principles computation and experimental measurements suggest that the electronic system is gapped, and there should be no…

利用RIXS研究非化学计量烧绿石铱酸盐Tb$_2$Ir$_2$O$_7$的自旋动力学与可能的拓扑磁振子

Spin dynamics and possible topological magnons in non-stoichiometric pyrochlore iridate Tb$_2$Ir$_2$O$_7$ studied by RIXS

本研究通过RIXS探究非化学计量烧绿石铱酸盐Tb$_{2+x}$Ir$_{2-x}$O$_{7-y}$的自旋动力学，发现其磁相互作用鲁棒，$D/J$比值支持拓扑磁振子能带交叉，或可同时实现费米子与玻色子拓扑。

Symmetry Analysis of Tensors in the Honeycomb Lattice of Edge-Sharing Octahedra

We obtain the most general forms of rank-2 and rank-3 tensors allowed by the crystal symmetries of the honeycomb lattice of edge-sharing octahedra for crystals belonging to different crystallographic point groups, including the monoclinic point group $2/m$ and the trigonal (or rhombohedral) point group $\bar{3}$. Our results are relevant for two-dimensional materials, such as $α$-RuCl$_3$, CrI$_3$, and the honeycomb iridates. We focus on the magnetic-field-dependent thermal conductivity tensor $κ_{ij}(\mathbf{H})$, which describes a system's longitudinal and thermal Hall responses, for the cas…

First demonstration of tuning between the Kitaev and Ising limits in a honeycomb lattice

Recent observations of novel spin-orbit coupled states have generated tremendous interest in $4d/5d$ transition metal systems. A prime example is the $J_{\text{eff}}=\frac{1}{2}$ state in iridate materials and $α$-RuCl$_{3}$ that drives Kitaev interactions. Here, by tuning the competition between spin-orbit interaction ($λ_{\text{SOC}}$) and trigonal crystal field splitting ($Δ_\text{T}$), we restructure the spin-orbital wave functions into a novel $μ=\frac{1}{2}$ state that drives Ising interactions. This is done via a topochemical reaction that converts Li$_{2}$RhO$_{3}$ to Ag$_{3}$LiRh$_{2}…

ilmenite $A$IrO$_3$ ($A$ = Mg, Zn, Cd) 和 hyperhoneycomb $β$-ZnIrO$_3$ 中的晶场和离子间相互作用的演变

Evolution of crystal field and intraionic interactions in the ilmenite $A$IrO$_3$ ($A$ = Mg, Zn, Cd) and hyperhoneycomb $β$-ZnIrO$_3$

通过Ir L3边共振非弹性x射线散射研究ilmenite iridates和hyperhoneycomb结构的局部电子结构，揭示了化学取代对晶场和离子间相互作用参数的影响，为理解Kitaev候选材料中的磁学行为提供了基础。

Impact of spin-orbit coupling on the magnetism of Sr3MIrO6 (M = Ni, Co)

Using density functional calculations, we demonstrate that the spin-orbit coupling (SOC) of the Ir4+ ion plays an essential role in determining the antiferromagnetism of the hexagonal spin-chain system Sr3MIrO6 (M = Ni, Co) by tuning the crystal-field level sequence and altering the Ir-M inter-orbital interactions. The SOC splits the e'_{g} doublet of the octahedral Ir4+ ion (t_{2g}^5) in a trigonal crystal field, and the single t_{2g} hole resides on the e'_{g} upper branch and gives rise to the antiferromagnetic superexchange. In absence of the SOC, however, the single t_{2g} hole would occu…

Non-collinear magnetic structure and multipolar order in Eu$_2$Ir$_2$O$_7$

The magnetic properties of the pyrochlore iridate material Eu$_2$Ir$_2$O$_7$ (5$d^5$) have been studied based on the first principle calculations, where the crystal field splitting $Δ$, spin-orbit coupling (SOC) $λ$ and Coulomb interaction $U$ within Ir 5$d$ orbitals are all playing significant roles. The ground state phase diagram has been obtained with respect to the strength of SOC and Coulomb interaction $U$, where a stable anti-ferromagnetic ground state with all-in/all-out (AIAO) spin structure has been found. Besides, another anti-ferromagnetic states with close energy to AIAO have also…