Possible Kitaev Quantum Spin Liquid State in 2D Materials with S=3/2

Spin-Liquid--to--Spin-Liquid Transition in Kitaev Magnets Driven by Fractionalization

While phase transitions between magnetic analogs of three states of matter --- a long-range ordered state, paramagnet, and spin liquid --- have been extensively studied, the possibility of "liquid-liquid" transitions, namely, between different spin liquids, remains elusive. By introducing the additional Ising coupling into the honeycomb Kitaev model with bond asymmetry, we discover that the Kitaev spin liquid turns into a spin-nematic quantum paramagnet before a magnetic order is established by the Ising coupling. The quantum phase transition between the two liquid states accompanies a topolog…

凯拉夫反铁磁体在[111]磁场中的量子自旋液体和自旋翻转相的出现

Emergence of quantum spin liquid and spin-flop phase in Kitaev antiferromagnets in a [111] magnetic field

本研究通过精确对角化计算揭示了凯拉夫反铁磁体在[111]磁场中的量子自旋液体和自旋翻转相的出现，发现其在中间磁场区域存在标量和向量旋磁序。

Competition between static and dynamic magnetism in the Kitaev spin liquid material Cu2IrO3

Anyonic excitations emerging from a Kitaev spin liquid can form a basis for quantum computers. Searching for such excitations motivated intense research on the honeycomb iridate materials. However, access to a spin liquid ground state has been hindered by magnetic ordering. Cu2IrO3 is a new honeycomb iridate without thermodynamic signatures of a long-range order. Here, we use muon spin relaxation to uncover the magnetic ground state of Cu2IrO3. We find a two-component depolarization with slow and fast relaxation rates corresponding to distinct regions with dynamic and static magnetism, respect…

Topological $Z_2$ invariant in Kitaev spin liquids: Classification of gapped spin liquids beyond projective symmetry group

A projective symmetry group (PSG) has been regarded as a classification theory of spin liquids. However, it does not include a symmetry-protected topological order of fermionic spinon excitations, and thus the classification of gapped spin liquids is incomplete. We demonstrate the classification beyond PSG by utilizing the Kitaev model on the squareoctagon lattice, where two gapped spin liquids are distinguished by a topological $Z_2$ invariant. This $Z_2$ invariant can be defined solely by the time-reversal and translation symmetries on condition that the time-reversal symmetry is implemented…

OsCl$_3$中Kitaev量子自旋液相可行路径的计算探索

Computational exploration of a viable route to Kitaev-quantum spin liquid phase in OsCl$_3$

本研究通过计算结合二阶微扰与赝费米子重整化群方法，发现单层OsCl$_3$的小$J_\text{H}$/$U$区域存在Kitaev量子自旋液相，且其更远邻相互作用可忽略，是更优的候选材料，为通过外延应变调控探测磁相变提供了思路。

空穴掺杂Kitaev自旋液体的动力学铁磁性与拓扑磁子

Kinetic Ferromagnetism and Topological Magnons of the Hole-Doped Kitaev Spin Liquid

通过DMRG模拟与parton平均场理论，揭示了空穴掺杂Kitaev自旋液体在微小跳跃强度下即可通过无序诱导有序机制破坏分数化并引发铁磁极化，各向异性交换则驱动其进入具有手性磁子的拓扑铁磁态。

Thermodynamic evidence for field-angle dependent Majorana gap in a Kitaev spin liquid

The exactly-solvable Kitaev model of two-dimensional honeycomb magnet leads to a quantum spin liquid (QSL) characterized by Majorana fermions, relevant for fault-tolerant topological quantum computations. In the high-field paramagnetic state of $α$-RuCl3, half-integer quantization of thermal Hall conductivity has been reported as a signature of edge current, but the bulk nature of this state remains elusive. Here, from high-resolution heat capacity measurements under in-plane field rotation, we find strongly angle-dependent low-energy excitations in bulk $α$-RuCl3. The excitation gap has a sex…

Possible Quantum Paraelectric State in Kitaev Spin Liquid Candidate H$_{3}$LiIr$_{2}$O$_{6}$

A new quantum spin liquid (QSL) candidate material H$_{3}$LiIr$_{2}$O$_{6}$ was synthesized recently and was found not to show any magnetic order or phase transition down to low temperatures. In this work, we study the quantum dynamics of the hydrogen ions, i.e., protons, in this material by combining first-principles calculations and theoretical analysis. We show that each proton and its adjacent oxygen ions form an electric dipole. The dipole interactions and the proton tunneling are captured by a transverse-field Ising model with a quantum disordered paraelectric ground state. The dipole ex…

凯利夫量子自旋液体

Kitaev Quantum Spin Liquids

凯利夫模型提供了一种可解析的量子自旋液体例子，其基态为拓扑自旋液体，具有非阿贝尔任何子，可能为拓扑量子计算提供资源。

Anderson-Kitaev spin liquid

The bond-disordered Kitaev model attracts much attention due to the experimental relevance in $α$-RuCl$_3$ and $A_3$LiIr$_2$O$_6$ ($A=$ H, D, Ag, $\textit{etc.}$). Applying a magnetic field to break the time-reversal symmetry leads to a strong modulation in mass terms for Dirac cones. Because of the smallness of the flux gap of the Kitaev model, a small bond disorder can have large influence on itinerant Majorana fermions, and Majorana fermions will be in the Anderson localization state immediately. We call this immobile liquid state Anderson-Kitaev liquid state with two localized Majorana fer…

Thermal anyon interferometry in phonon-coupled Kitaev spin liquids

Recent theoretical studies inspired by experiments on the Kitaev magnet $α$-RuCl$_3$ highlight the nontrivial impact of phonons on the thermal Hall conductivity of chiral topological phases. Here we introduce mixed mesoscopic-macroscopic devices that allow refined thermal-transport probes of non-Abelian spin liquids with Ising topological order. These devices feature a quantum-coherent mesoscopic region with negligible phonon conductance, flanked by macroscopic lobes that facilitate efficient thermalization between chiral Majorana edge modes and bulk phonons. We show that our devices enable $(…

Revealing the Phase Diagram of Kitaev Materials by Machine Learning: Cooperation and Competition between Spin Liquids

Kitaev materials are promising materials for hosting quantum spin liquids and investigating the interplay of topological and symmetry-breaking phases. We use an unsupervised and interpretable machine-learning method, the tensorial-kernel support vector machine, to study the honeycomb Kitaev-$Γ$ model in a magnetic field. Our machine learns the global classical phase diagram and the associated analytical order parameters, including several distinct spin liquids, two exotic $S_3$ magnets, and two modulated $S_3 \times Z_3$ magnets. We find that the extension of Kitaev spin liquids and a field-in…