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arXiv · 1407.3480

Gate-tunable Phase Transitions in 1T-TaS$_2$

Yijun Yu·Fangyuan Yang·Xiu Fang Lu·Ya Jun Yan·Y. H. Cho·Liguo Ma·Xiaohai Niu·Sejoong Kim·Young-Woo Son·Donglai Feng·Shiyan Li·Sang-Wook Cheong·Xian Hui Chen·Yuanbo Zhang
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Abstract

The ability to tune material properties using gate electric field is at the heart of modern electronic technology. It is also a driving force behind recent advances in two-dimensional systems, such as gate-electric-field induced superconductivity and metal-insulator transition. Here we describe an ionic field-effect transistor (termed "iFET"), which uses gate-controlled lithium ion intercalation to modulate the material property of layered atomic crystal 1T-TaS$_2$. The extreme charge doping induced by the tunable ion intercalation alters the energetics of various charge-ordered states in 1T-TaS$_2$, and produces a series of phase transitions in thin-flake samples with reduced dimensionality. We find that the charge-density-wave states in 1T-TaS$_2$ are three-dimensional in nature, and completely collapse in the two-dimensional limit defined by their critical thicknesses. Meanwhile the ionic gating induces multiple phase transitions from Mott-insulator to metal in 1T-TaS$_2$ thin flakes at low temperatures, with 5 orders of magnitude modulation in their resistance. Superconductivity emerges in a textured charge-density-wave state induced by ionic gating. Our method of gate-controlled intercalation of 2D atomic crystals in the bulk limit opens up new possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.

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Yijun Yu, Fangyuan Yang, Xiu Fang Lu, Ya Jun Yan, Y. H. Cho, Liguo Ma, Xiaohai Niu, Sejoong Kim, Young-Woo Son, Donglai Feng, Shiyan Li, Sang-Wook Cheong, Xian Hui Chen, Yuanbo Zhang. 2014-07-13. Gate-tunable Phase Transitions in 1T-TaS$_2$. https://doi.org/10.1038/nnano.2014.323

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