Evidence of mixed dimensionality and decoupled charge-lattice orders in layered TaTe₂

Charge and lattice orders are generally coupled in charge density wave (CDW) materials and share identical order wavevectors. Although this situation is usually satisfied in a large class of 2D materials, it comes short in describing the so called CDW-like phase transition in layered tantalum ditelluride (TaTe2), accompanied by anomalous low temperature transport properties and a periodic lattice distortion. Here we combine angle-resolved photoemission spectroscopy (ARPES) and low energy electron diffractions (LEED) to directly access the charge and lattice in TaTe2 to understand the CDW-like phase transition. We find evidence for the role of mixed dimensionality together with anomalous entanglements between the charge and lattice orders. We will discuss these results in the general contest of CDW phase transitions and show how our findings provide a new platform and principles for engineering complex orders in 2D materials.