Strong electronic interactions can drive a system into a state with a symmetry breaking. Lattice frustration or competing interactions tend to prevent symmetry breaking, leading to quantum disordered phases. In spin systems frustration can produce a spin liquid state. Frustration of a charge degree of freedom also can result in various exotic states, however, experimental data on these effects is scarce. In this work we demonstrate how in a Mott insulator on a weakly anisotropic triangular lattice a charge ordered state melts on cooling down to low temperatures. Raman scattering spectroscopy finds that \(\kappa\)-(BEDT-TTF)\({}_{2}\)Hg(SCN)\({}_{2}\)Cl enters an insulating “dipole solid” state at \(T=30\,{\mathrm{K}}\), but below \(T=15\,{\mathrm{K}}\) the order melts, while preserving the insulating energy gap. Based on these observations, we suggest a phase diagram relevant to other quantum paraelectric materials.

强大的电子交互可以使系统进入对称破坏状态。晶格的挫败或竞争性相互作用倾向于防止对称性破裂，从而导致量子无序相。在自旋系统中，挫折会产生自旋液体状态。冲锋自由度的挫折也可能导致各种外来状态，但是，关于这些作用的实验数据很少。在这项工作中，我们演示了在弱各向异性三角晶格上的Mott绝缘子中，有序状态在冷却至低温时如何熔化。拉曼散射光谱法发现\（\ kappa \） -（BEDT-TTF）\ {{} _ {2} \） Hg（SCN）\ {{} _ {2} \） Cl进入绝缘的“偶极固体”状态位于\（T = 30 \，{\ mathrm {K}} \），但低于\（T = 15 \，{\ mathrm {K}} \）顺序熔化，同时保留绝缘能隙。基于这些观察，我们提出了与其他量子顺电材料有关的相图。