Gate induced superconductivity in layered material based electronic double layer field effect transistors

Applying the principle of field effect transistor to layered materials provides new opportunities to manipulate their electronic properties for interesting sciences and applications. Novel gate dielectrics like electronic double layer (EDL) formed by ionic liquids are demonstrated to achieve an electrostatic surface charge accumulation on the order of 10¹⁴ cm^-2. To realize electric field-induced superconductivity, we chose a layered compound: ZrNCl, which is known to be superconducting by introducing electrons through intercalation of alkali metals into the van der Waals gaps. A ZrNCl-based EDL transistor was micro fabricated on a thin ZrNCl single crystal made by mechanical micro-cleavage. Accumulating charges using EDL gate dielectrics onto the channel surface of ZrNCl shows effective field effect modulation of its electronic properties. Sheet resistance of ZrNCl EDL transistor is reduced by applying a gate voltage from 0 to 4.5 V. Temperature dependence of sheet resistance showed clear evidence of metal-insulator transition upon gating, observed at a gate voltage higher than 3.5 V. Furthermore, gate-induced superconductivity took place after metal-insulator transition when the transistor is cooled down to about 15 K.