@Article{RodriguesJúniorCRSFRAMM:2023:LoSuEl,
               author = "Rodrigues J{\'u}nior, Gilberto and Chagas, Tha{\'{\i}}s and 
                         Reis, Rafael and Sciammarella, Paulo Victor and Fornari, Celso 
                         Israel and Rappl, Paulo Henrique de Oliveira and Abramof, Eduardo 
                         and Magalh{\~a}es Paniago, Rog{\'e}rio and Malachias, 
                         {\^A}ngelo",
          affiliation = "{Universidade Federal de Minas Gerais (UFMG)} and 
                         {Universit{\"a}t Siegen} and {Universidade Federal de Minas 
                         Gerais (UFMG)} and {Universidade Federal de Vi{\c{c}}osa (UFV)} 
                         and {Universit{\"a}t W{\"u}rzburg} and {Instituto Nacional de 
                         Pesquisas Espaciais (INPE)} and {Instituto Nacional de Pesquisas 
                         Espaciais (INPE)} and {Universidade Federal de Minas Gerais 
                         (UFMG)} and {Universidade Federal de Minas Gerais (UFMG)}",
                title = "Local surface electronic response of Bi 2 Te 3 topological 
                         insulator upon europium doping",
              journal = "Physical Review B",
                 year = "2023",
               volume = "108",
                pages = "e035408",
                month = "July",
             abstract = "The most relevant characteristic of a topological insulator 
                         material is the presence of edge/surface states that are protected 
                         by the bulk topology, and therefore, insensitive to nonmagnetic 
                         disorder. However, if such disorder is induced by magnetic atoms 
                         or the topological insulator is subjected to an external magnetic 
                         field, the time-reversal symmetry is expected to break down, 
                         affecting the robustness of the edge/surface states. In this work, 
                         europium (Eu)-doped bismuth telluride thin films were grown by 
                         molecular beam epitaxy in order to analyze the effect of a small 
                         fraction of atoms with magnetic properties on topologically 
                         protected surface states. For films with different Eu 
                         concentrations, morphological and electronic characterizations 
                         were carried out using atomic force microscopy, scanning 
                         tunnelling microscopy, and scanning tunnelling spectroscopy (STS) 
                         techniques. The results show that, regardless of the Eu 
                         concentration, the layered structure characteristic of the Bi 2 Te 
                         3 phase is maintained. However, large ( > 2 % ) Eu concentrations 
                         induce the appearance of protrusions and clusters on the surface 
                         of the films. The STS measurements show the presence of surface 
                         states for pure and low-content Eu: Bi 2 Te 3 . The suppression of 
                         surface states is indicated by STS spectra in regions with 
                         well-defined gaps for some locally limited regions of our samples 
                         with large concentration of Eu atoms. From density functional 
                         theory we are able to show that the Eu substitutional impurity at 
                         the Bi site is not the main mechanism responsible for the observed 
                         changes in the topological insulator band structure. Furthermore, 
                         the magnetic properties of europium are not the key factor 
                         dictating the different Bi 2 Te 3 local surface electronic 
                         properties experimentally observed by STS, which are mostly 
                         affected by alloying and atom replacement, which induce a chemical 
                         modification of the surface potential.",
                  doi = "10.1103/PhysRevB.108.035408",
                  url = "http://dx.doi.org/10.1103/PhysRevB.108.035408",
                 issn = "1098-0121",
             language = "en",
           targetfile = "PhysRevB.108.035408.pdf",
        urlaccessdate = "04 maio 2024"
}