Multiple Charge density waves and structural superlattices in TmTe2 and TmTe3 few layer.

We have grown thulium tellurides (TmTe2, TmTe3) few layers on graphene/SiC(0001) by molecular beam epitaxy. The charge density waves (CDWs) and structural superlattices (SSLs) are investigated by scanning tunneling microscopy. Two CDWs are confirmed on surface of metallic TmTe3. The wave vectors are perpendicular to each other with length to be 0.29c* and 0.32a* respectively. SSLs with various periods are unveiled on the surface of TmTe2 and TmTe3. The electronic structures of these films are semiconducting. These results show that superlattice patterns in rare earth tellurides has two origins, CDWs or SSLs.