Periodic surface modulation of $(LaSe{)}_{1.14}(NbS{e}_2)$ observed by scanning tunneling microscopy

Fourier transformation of atomically resolved STM topography of $(LaSe{)}_{1.14}(NbS{e}_2)$ revealed a surface modulation along the hexagonal surface lattice of $NbS{e}_2$ layer, but with a two times larger period. We compare it to the modified charge density wave found on plain $NbS{e}_2$ under strain.