论文标题
低维金属有机磁铁作为通往S = 2 haldane相的途径
Low-dimensional metal-organic magnets as a route towards the S=2 Haldane phase
论文作者
论文摘要
金属有机磁铁（MOMS），金属原子通过有机接头连接的模块化磁性材料，是下一代量子技术的有前途的候选者。妈妈很容易形成低维结构，因此理想的系统也是实现关键量子模型的物理示例，包括haldane相，其中拓扑激发差距发生在整数旋转抗fiferromagnetic（AFM）链中。迄今为止，霍尔丹阶段仅以$ s = 1 $确定，而$ s \ geq 2 $仍未实现，因为较大的旋转对磁相互作用施加了更严格的要求。在这里，我们报告了CRCL $ _2 $（PYM）（PYM =吡啶胺）的结构和磁性特性，这是一种新的Quasi-1d $ s = 2 $ afm Mom。 We show, using X-ray and neutron diffraction, bulk property measurements, density-functional theory calculations and inelastic neutron spectroscopy (INS) that CrCl$_2$(pym) consists of AFM CrCl$_2$ spin chains ($J_1=-1.13(4)\;$meV) which are weakly ferromagnetically coupled through bridging pym （$ j_2 = 0.10（2）\; $ meV），具有易于轴各向异性（$ d = -0.15（3）\; $ mev）。我们发现，尽管与$ J_1 $相比，这些其他相互作用足以防止在该材料中观察到Haldane阶段。尽管如此，与Haldane阶段的接近以及妈妈的模块化表明，分层的CR（II）妈妈是一个有前途的家庭，可以寻找难以捉摸的$ S = 2 $ haldane阶段。
Metal-organic magnets (MOMs), modular magnetic materials where metal atoms are connected by organic linkers, are promising candidates for next-generation quantum technologies. MOMs readily form low-dimensional structures, and so are ideal systems to realise physical examples of key quantum models, including the Haldane phase, where a topological excitation gap occurs in integer-spin antiferromagnetic (AFM) chains. Thus far the Haldane phase has only been identified for $S=1$, with $S \geq 2$ still unrealised because the larger spin imposes more stringent requirements on the magnetic interactions. Here, we report the structure and magnetic properties of CrCl$_2$(pym) (pym=pyrimidine), a new quasi-1D $S=2$ AFM MOM. We show, using X-ray and neutron diffraction, bulk property measurements, density-functional theory calculations and inelastic neutron spectroscopy (INS) that CrCl$_2$(pym) consists of AFM CrCl$_2$ spin chains ($J_1=-1.13(4)\;$meV) which are weakly ferromagnetically coupled through bridging pym ($J_2=0.10(2)\;$meV), with easy-axis anisotropy ($D=-0.15(3)\;$meV). We find that although small compared to $J_1$, these additional interactions are sufficient to prevent observation of the Haldane phase in this material. Nevertheless, the proximity to the Haldane phase together with the modularity of MOMs suggests that layered Cr(II) MOMs are a promising family to search for the elusive $S=2$ Haldane phase.
