Gate-tunable phase transitions in thin flakes of 1T-TaS2

Abstract

The ability to tune material properties using gating by electric fields is at the heart of modern electronic technology. It is also a driving force behind recent advances in two-dimensional systems, such as the observation of gate electric-field-induced superconductivity and metal-insulator transitions. Here, we describe an ionic field-effect transistor (termed an iFET), in which gate-controlled Li ion intercalation modulates the material properties of layered crystals of 1T-TaS2. The strong charge doping induced by the tunable ion intercalation alters the energetics of various charge-ordered states in 1T-TaS2 and produces a series of phase transitions in thin-flake samples with reduced dimensionality. We find that the charge-density wave states in 1T-TaS2 collapse in the two-dimensional limit at critical thicknesses. Meanwhile, at low temperatures, the ionic gating induces multiple phase transitions from Mott-insulator to metal in 1T-TaS2 thin flakes, with five orders of magnitude modulation in resistance, and superconductivity emerges in a textured charge-density wave state induced by ionic gating. Our method of gate-controlled intercalation opens up possibilities in searching for novel states of matter in the extreme charge-carrier-concentration limit.

Metallic Vanadium Disulfide Nanosheets as a Platform Material for Multifunctional Electrode Applications

“…Notably, the distinct cation dependence combined with the ∝ −1/2 relationship (blue dashed line in Figure 5h) indicates that, this 12 capacitive behavior is associated with a semi-infinite linear diffusion process 50 , namely, intercalation of alkali metal ions into the vdW gap, rather than simply electrostatic adsorption on the VS2 surface. This has been further corroborated by our electrochemical impedance spectroscopy measurements provided in Supplementary Figure S15.…”

“…Recently, there has been renewed research interest in these MTMDCs (TaS2, NbSe2, etc. ), as they have proven to be ideal systems for exploring collective electronic states down to the two-dimensional (2D) limit [11][12][13][14] . More intriguingly, the excellent electrical conductivity and lack of bandgaps in these layered materials also indicate a broad range of potential applications such as transparent electrodes 15 and energy conversion/storage 16 , if they can be thinned down to the nanoscale.…”

Spin density waves predicted in zigzag puckered phosphorene, arsenene and antimonene nanoribbons

“…The charge doping can be realized by building an ionic field-effect transistor, in which gate-controlled Li ion intercalation modulates the material properties of layered crystals. 31 In summary, the effects arising from the Peierls instability of zigzag Puckered Vene nanoribbons (ZVNRs) is systematically investigated. Our calculated results show that the ground state of ZVNRs is a spin density wave (SDW) mode.…”

Total-Ionizing-Dose Effects on Threshold Switching in $1{T}$ -TaS2 Charge Density Wave Devices

“…With no gate or electric field, the charge yield in the h-BN is low [3], and the resulting changes in device characteristics are smaller than those seen in gated graphene-based transistors similarly passivated by h-BN [16]. The other important feature of 1T -TaS 2 is the very high carrier concentration in both NC-CDW and IC-CDW states, on the order of 10 21 cm −3 and 10 22 cm −3 , respectively [11], [12]. These values are much higher than those in conventional semiconductor devices; they are closer to those of metals and/or graphene away from the Dirac point [13], [17].…”

“…The transition between the nearly commensurate (NC-CDW) phase and incommensurate (IC-CDW) phase reveals itself as an abrupt change in resistivity of the device channel accompanied by hysteresis. The carrier concentrations in the two CDW states are very high: 10 21 cm −3 and 10 22 cm −3 for the high resistive NC-CDW and low resistive IC-CDW phases, respectively [11], [12]. Unlike conventional FETs, the 1T -TaS 2 device is a two-terminal device in which the switching is controlled by the source-drain voltage rather than the gate voltage.…”