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Interface between crystalline topological insulators and 2D-trivial materials: defect proximity study

Grant number: 19/04527-0
Support type:Scholarships in Brazil - Doctorate (Direct)
Effective date (Start): June 01, 2019
Effective date (End): January 31, 2023
Field of knowledge:Physical Sciences and Mathematics - Physics - Condensed Matter Physics
Principal researcher:Adalberto Fazzio
Grantee:Bruno Focassio
Home Institution: Centro de Engenharia, Modelagem e Ciências Sociais Aplicadas (CECS). Universidade Federal do ABC (UFABC). Ministério da Educação (Brasil). Santo André , SP, Brazil
Associated research grant:17/02317-2 - Interfaces in materials: electronic, magnetic, structural and transport properties, AP.TEM


We call topological quantum states when the wave function has a distinct character that can be specified by a topological invariant, a discrete quantity that remains unchanged under adiabatic transformations. Topological insulators is a class of materials where there is a strong coupling between the momentum and degree of freedom of the spin. Topological insulators (TI) are materials that have an insulating bulk and a surface with protected metallic states, for example, by time reversal, and which are characterized by a topological invariant called Z2. More recently inspired by TI researchers have sought other topological phases with different protections from time-reversal. Crystalline Topological Insulators (TCIs) are topological phases of matter that are protected by crystal symmetry, this including rotations, mirror plane etc. In the case of crystalline topological insulation requires a definition of the Chern number. The TCI search system requires a classification of its topologically distinct band structures within each crystal class, and a complete classification of the TCI does not yet exist and this search is one of our challenges. Through this project we tried to answer some important questions for the area: (i) among the many 2D, dual topological (DTC) and TCI materials already proposed via Machine Learning, how can we classify them via a point group and how can it be connected to its protection?; (ii) how to interfaces with trivial substances can break their protection by symmetry by proximity effect when the substrate interacts via van der Waals?; (iii) the application of these is a field of research well studied, and all of them seek to use the surface in the case of 3D, and the edges in 2D cases. We know that in the case of TIs this is connected to the value of the band gap and the values of spin-orbit coupling. Using the existing database we propose to develop a descriptor for Machine Learning in order to predict the most favorable conditions; (iv) finally, to study access to the Rashba states, these effects persist in topological insulation and are important if we are to manipulate spin. Understanding and controlling spin carriers is of major interest in the field of spintronics. (AU)

Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
FOCASSIO, BRUNO; SCHLEDER, GABRIEL R.; COSTA, MARCIO; FAZZIO, ADALBERTO; LEWENKOPF, CAIO. Structural and electronic properties of realistic two-dimensional amorphous topological insulators. 2D MATERIALS, v. 8, n. 2 APR 2021. Web of Science Citations: 1.
PEZO, ARMANDO; FOCASSIO, BRUNO; SCHLEDER, GABRIEL R.; COSTA, MARCIO; LEWENKOPF, CAIO; FAZZIO, ADALBERTO. Disorder effects of vacancies on the electronic transport properties of realistic topological insulator nanoribbons: The case of bismuthene. PHYSICAL REVIEW MATERIALS, v. 5, n. 1 JAN 19 2021. Web of Science Citations: 0.
FOCASSIO, BRUNO; SCHLEDER, GABRIEL R.; PEZO, ARMANDO; COSTA, MARCIO; FAZZIO, ADALBERTO. Dual topological insulator device with disorder robustness. Physical Review B, v. 102, n. 4 JUL 14 2020. Web of Science Citations: 0.

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