Memristive phase switching in two-dimensional 1T-TaS2 crystals.
Memristive phase switching in two-dimensional 1T-TaS2 crystals.
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DOI：
10.1126/sciadv.1500606
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发表时间：
2015-10
期刊：
影响因子：
13.6
通讯作者：
Iwasa Y
中科院分区：
文献类型：
--
作者：
Yoshida M;Suzuki R;Zhang Y;Nakano M;Iwasa Y
相关二维晶体中多个新的亚稳态的电学转换。将材料缩小到原子层的水平可以产生丰富的物理和化学性质，如各种二维(2D)晶体，包括石墨烯、过渡金属二卤化物和黑磷。这是由电子能带结构的戏剧性变化引起的。在这种减小的维度中，电子关联效应也有望与体相系统发生显著变化。然而，在相关的2D晶体中实现新现象的尝试很少。本文报道了纳米厚晶1T型二硫化钽(1T-TaS_2)的记忆相变，这是一个一级相变系统。发现随着厚度的减小，相变的有序化动力学变得非常缓慢，从而导致亚稳态的出现。此外，通过施加平面内电场，我们实现了史无前例的多步非挥发状态的记忆转换。厚度的减小对于实现这种非易失性电开关行为是必不可少的。稀化诱导的慢动力学可能使各种亚稳态变得健壮，从而实现非易失性存储操作。这一结果表明，具有关联电子的2D晶体是一种新型的纳米系统，可以探索和功能化体相中无法获得的多种亚稳态。
Electrical switching to multiple novel metastable states in a correlated two-dimensional crystal. Scaling down materials to an atomic-layer level produces rich physical and chemical properties as exemplified in various two-dimensional (2D) crystals including graphene, transition metal dichalcogenides, and black phosphorus. This is caused by the dramatic modification of electronic band structures. In such reduced dimensions, the electron correlation effects are also expected to be significantly changed from bulk systems. However, there are few attempts to realize novel phenomena in correlated 2D crystals. We report memristive phase switching in nano-thick crystals of 1T-type tantalum disulfide (1T-TaS2), a first-order phase transition system. The ordering kinetics of the phase transition were found to become extremely slow as the thickness is reduced, resulting in an emergence of metastable states. Furthermore, we realized unprecedented memristive switching to multistep nonvolatile states by applying an in-plane electric field. The reduction of thickness is essential to achieve such nonvolatile electrical switching behavior. The thinning-induced slow kinetics possibly make the various metastable states robust and consequently realize the nonvolatile memory operation. The present result indicates that a 2D crystal with correlated electrons is a novel nano-system to explore and functionalize multiple metastable states that are inaccessible in its bulk form.