We would like to invite you to our next ICMAB Invited Seminar by Gabriel Sánchez Santolino, from Universidad Complutense de Madrid.
The seminar will take place at the Sala d'Actes Carles Miravitlles
by Gabriel Sánchez Santolino, from Universidad Complutense de Madrid, Dept. Física de Materiales
Wednesday, 26 October 2022
ICMAB-Sala d'Actes Carles Miravitlles
The functional properties of van der Waals (vdW) two-dimensional materials are highly sensitive to structural distortions such as ripplings or corrugations. In franckeite, a naturally occurring vdW heterostructure, we have shown how a mismatch between its constituent pseudohexagonal and pseudotetragonal two-dimensional layers gives rise to a spontaneous rippling that is responsible for a strong anisotropic strain that affects the electrical, vibrational, and optical properties of the material . Moreover, small variations in the multilayered structure and composition of this material can give rise to a strong topological insulator phase .
In this seminar we will talks about how four-dimensional scanning transmission electron microscopy (4D-STEM) can allow us to map the local structural modulations occurring in this material and characterize the strong strain fields arising from a 3D structural rippling. In 4D-STEM, we measure a full 2D image of the transmitted electron beam, or a convergent beam electron diffraction pattern (CBED) as the electron beam is raster scanned over a 2D grid of probe positions in real space, as schematized in the figure below (Fig. 1) 4D-STEM brings thus a new pathway to study the structural and physical properties of 2D materials and heterostructures.
 R. Frisenda, G. Sanchez-Santolino, N. Papadopoulos, J. Urban, M. Baranowski, A. Surrente, D.K. Maude, M. Garcia-Hernandez, H. S. J. van der Zant, P. Plochocka, P. San-Jose and A. Castellanos-Gomez, Nano Letters, 20 2 (2020) 1141–1147
 W. S. Paz, M. G. Menezes, N. N. Batista, G. Sanchez-Santolino, M. Velický, M. Varela, R. B. Capaz and J. José Palacios, Nano Letters, 21 18 (2021) 7781-7788
Hosted by Jaume Gázquez, MULFOX group, ICMAB-CSIC