Electrochemical Control of Magnetism on the Breathing Kagome Network of LixScMo3O8

Controlling properties within a given functional inorganic
material
structure type is often accomplished through tuning the electronic
occupation, which is in turn dictated by the elemental composition
determined at the time of material preparation. We employ electrochemical
control of the lithium content, with associated electronic occupancy
control, to vary the magnetic properties of a material where a kagome-derived
network of Mo3 triangles carry the spin. In this case,
Li is electrochemically inserted into LiScMo3O8, a layered compound containing a breathing Mo kagome network. Up
to two additional Li can be inserted into LiScMo3O8, transforming it into Li3ScMo3O8. Li2ScMo3O8 prepared by
electrochemical lithiation is compared to the quantum spin liquid
candidate compound Li2ScMo3O8 prepared
through high-temperature solid-state methods, which has a slightly
different structural stacking sequence but a similar kagome-derived
network. Magnetic measurements are supported by first-principles calculations,
showing that electrons remain localized on the Mo clusters throughout
the doping series. As x is varied in LixScMo3O8, the measurements and
calculations reveal the evolution from a diamagnetic band insulator
at x = 1 to a geometrically frustrated magnet at x = 2, back to a diamagnetic insulator at x = 3. These results indicate a likelihood of strong coupling between
the degree of Li disorder and charge/magnetic ordering over the Mo3 clusters.

在特定的功能无机材料结构类型中，调控其控制性质通常通过调整电子占据度来实现，而电子占据度又受到材料制备时确定的元素组成所决定。本研究通过电化学控制锂含量及其相关的电子占据度，以改变材料中携带自旋的kagome型Mo3三角形网络的磁性性质。具体而言，锂通过电化学方式被引入LiScMo3O8，这是一种含有呼吸型Mo kagome网络的层状化合物。在LiScMo3O8中，最多可以额外插入两个锂原子，从而转化为Li3ScMo3O8。通过电化学锂化制备的Li2ScMo3O8与通过高温固相方法制备的量子自旋液体候选化合物Li2ScMo3O8进行比较，后者具有略微不同的结构堆叠顺序，但拥有相似的kagome型网络。磁性测量得到了第一性原理计算的支持，表明在整个掺杂系列中，电子始终局限于Mo簇上。随着LixScMo3O8中的x值变化，测量和计算揭示了从x = 1时的抗磁性绝缘体带演变至x = 2时的几何上受挫的磁性体，再回到x = 3时的抗磁性绝缘体。这些结果暗示了锂无序程度与Mo3簇上的电荷/磁性有序之间的强耦合可能性。