Intercalation of van der Waals layered materials: A route towards engineering of electron correlation**Project supported by the National Key Basic Research Program of China (Grant Nos. 2013CBA01603, 2016YFA0300600, and 2016YFA0300903), the National Natural Science Foundation of China (Grant Nos. 11574005, 11774009, 11222436, and 11574283), and the National Postdoctoral Program for Innovative Talents of China (Grant No. BX201700012) funded by China

Abstract

Being parent materials of two-dimensional (2D) crystals, van der Waals layered materials have received revived interest. In most 2D materials, the interaction between electrons is negligible. Introducing the interaction can give rise to a variety of exotic properties. Here, via intercalating a van der Waals layered compound VS2, we find evidence for electron correlation by extensive magnetic, thermal, electrical, and thermoelectric characterizations. The low temperature Sommerfeld coefficient is 64 mJ⋅K−2⋅mol−1 and the Kadowaki–Woods ratio rKW ∼ 0.20a0. Both supports an enhancement of the electron correlation. The temperature dependences of the resistivity and thermopower indicate an important role played by the Kondo effect. The Kondo temperature TK is estimated to be around 8 K. Our results suggest intercalation as a potential means to engineer the electron correlation in van der Waals materials, as well as 2D materials.