论文标题
在$ \ it {d^7} $ kitaev honeycomb磁铁中，竞争抗铁磁 - 铁磁性状态
Competing Antiferromagnetic-Ferromagnetic States in $\it{d^7}$ Kitaev Honeycomb Magnet
论文作者
论文摘要
Kitaev模型是可以分析可解决且在物理上可见的汉密尔顿的罕见例子，产生了拓扑量子自旋液态态。 Here we report signatures of Kitaev spin liquid physics in the honeycomb magnet $Li_3Co_2SbO_6$, built of high-spin $\it{d^7}$ ($Co^{2+}$) ions, in contrast to the more typical low-spin $\it{d^5}$ electron configurations in the presence of large spin-orbit coupling.中子粉末衍射测量，热量和磁化研究支持$ \ it {c_c} 2/\ it {m} $的远程防铁磁订单空间组的发展，低于$ \ it {t_n} $ = 11 k at $ \ it $ \ it $ \ it $ = 0 t。估计为0.6rln2，与接近Kitaev量子旋转液态的系统的预期值非常吻合。温度依赖性磁顺序参数表明$β$值为0.19（3），与XY各向异性和平面订购一致，并在层之间具有类似Ising的相互作用。此外，我们在$ \ iT $ \ it {μ_0H} $ 0.7 t的应用磁场下观察到{C} 2/\ it {c} 2/\ it {m} $的空间组的自旋驱动的交叉序列 过渡。 $ \ it {d^7} $指南针模型，对$ li_3co_2sbo_6 $的特定热量的定量比较，以及相关的蜂窝均与各向异性Kitaev模型均匀，进一步支持与Kitaev Spin Liquid State的接近。该材料展示了用于旋转液体候选物的高旋转$ \ it {d^7} $系统的丰富游乐场，并补充了已知的$ \ it {d^5} $ ir-和ru基材料。
The Kitaev model is a rare example of an analytically solvable and physically instantiable Hamiltonian yielding a topological quantum spin liquid ground state. Here we report signatures of Kitaev spin liquid physics in the honeycomb magnet $Li_3Co_2SbO_6$, built of high-spin $\it{d^7}$ ($Co^{2+}$) ions, in contrast to the more typical low-spin $\it{d^5}$ electron configurations in the presence of large spin-orbit coupling. Neutron powder diffraction measurements, heat capacity, and magnetization studies support the development of a long-range antiferromagnetic order space group of $\it{C_C}2/\it{m}$, below $\it{T_N}$ = 11 K at $\it{μ_0H}$ = 0 T. The magnetic entropy recovered between $\it{T}$ = 2 K and 50 K is estimated to be 0.6Rln2, in good agreement with the value expected for systems close to a Kitaev quantum spin liquid state. The temperature-dependent magnetic order parameter demonstrates a $β$ value of 0.19(3), consistent with XY anisotropy and in-plane ordering, with Ising-like interactions between layers. Further, we observe a spin-flop driven crossover to ferromagnetic order with space group of $\it{C}2/\it{m}$ under an applied magnetic field of $\it{μ_0H}$ $\approx$ 0.7 T at $\it{T}$ = 2 K. Magnetic structure analysis demonstrates these magnetic states are competing at finite applied magnetic fields even below the spin-flop transition. Both the $\it{d^7}$ compass model, a quantitative comparison of the specific heat of $Li_3Co_2SbO_6$, and related honeycomb cobaltates to the anisotropic Kitaev model further support proximity to a Kitaev spin liquid state. This material demonstrates the rich playground of high-spin $\it{d^7}$ systems for spin liquid candidates, and complements known $\it{d^5}$ Ir- and Ru-based materials.
