| Abstract: | We report scanning tunneling microscopy investigation on epitaxial ultrathin films of pyrite-type copper disulfide.Layer-by-layer growth of CuS_(2 )films with a preferential orientation of(111)on SrTiO_3(001)and Bi_2Sr_2Ca Cu_2O_(8+)substrates is achieved by molecular beam epitaxy growth.For ultrathin films on both kinds of substrates,we observe symmetric tunneling gap around the Fermi level that persists up to~15 K.The tunneling gap degrades with either increasing temperature or increasing thickness,suggesting new matter states at the extreme twodimensional limit. |
