Layer decoupling by alkali metal intercalations in MoTe2

2D materials are known to support a wide range of unique quantum phenomena that manifest near the Fermi energy. It is of great interest to modify and tailor those materials to endow novel functionalities beyond their pristine nature. Many approaches such as strain, chemical doping, surface modification, and ultrafast laser excitation have been employed to achieve this purpose. Here, we show how one may manipulate the electronic structure of 1T’-MoTe₂ in non-trivial ways by potassium adsorption. To probe this material, which is suggested to host a topological phase at lower temperatures, we employ angle-resolved photoemission spectroscopy in combination with complementary surface-sensitive analytical tools such as low-energy electron diffraction, scanning tunneling microscopy, and angle-dependent x-ray photoemission spectroscopy. We show that potassium atom deposition results in electronic structure changes in two consecutive steps: For small amounts of K, we find a simple rigid band shift, while for larger amounts of K, MoTe₂ undergoes significant band structure renormalization. We show that during these changes, 1T’-MoTe₂ undergoes a Lifshitz transition. In combination with DFT, these results demonstrate that the origin of this electronic structure change stems from alkali metal intercalation, effectively decoupling the 2D sheets.