University of Alicante

Given by: Werner Brämer Escamilla

Date and hour: Jueves 20 de junio de 2019 a las 12:30h

Place: Sala Polivalente del Departamento de Física Aplicada de la Facultad de Ciencias Fase 2 (2ª Planta)

Twenty-first edition of the Physics symposia with "Vibroacústica en el Grado de Física de la Universidad de Alicante" given by Jaime Ramis Soriano, Full Professor of the Department of  Physics, Systems Engineering and Signal Theory at the University of Alicante.

This coloquium is open to the public in general and especially to the students of the Degree in Physics of the UA.

The coloquium will take place on Tuesday, April 9, at 09:30 horas, in the Board Room of the Faculty of Sciencies of the University of Alicante

Twentieth edition of the Physics symposia with "Ciencia "Fricción": algo chirría en la pantalla" taught by Juan Ángel Vaquerizo, of the Astrobiology Center of the CSIC-INTA.

This colloquium is open to the public in general and especially to the students of the Degree in Physics of the UA.

The colloquium will take place on Thirsday, March 27, at 17:00 am, in the CI/0002 Room in Phase 2 of the Faculty of Sciences of the University of Alicante.

Given by: Mª del Pilar García del Moral Zabala

Date and hour: Miércoles 27 de febrero de 2019 a las 11:30h

Place: Sala Polivalente del Departamento de Física Aplicada de la Facultad de Ciencias Fase 2 (2ª Planta)

Abstract:

In this talk I will address several goals that string theory, and M-theory as a unification theory, have to achieve in order to be quantum consistent theories modelling our world. I will discuss the role that fluxes can play to this respect when applied to the M2-brane theory based on our latest results.

Given by: Reyes Calvo Urbina

Date and hour: Tuesday, 26 february 2019, 12:00h

Place: Polivalent Room of the Department of Physics Applied, Faculty of Science, Phase 2 (2nd Floor)

Abstract:

In the Quantum Spin Hall textbook picture, a 2-dimensional topologically non-trivial insulator (2D-TI) is expected to present conductive edge states protected against backscattering. The application of a magnetic field should lift this protection, and above a critical field the material would enter a trivial insulator regime, where the edge conduction fully disappears.

In real 2d-TI materials, such as inverted HgTe quantum wells, however, the picture is more complex and scattering occurs over long enough distances (around microns). Furthermore, although the resistance of the devices increases in the presence of a magnetic field, certain predictions, such as the complete removal of edge conduction have not yet been directly probed.

In our work, we use novel probe techniques to tackle some of the above challenges for HgTe quantum wells. Microwave Impedance Microscopy and magnetotransport experiments allow us to probe the properties of helical states under broken time reversal symmetry and reveal that edge conduction persists unexpectedly at high magnetic fields and. Scanning Gate Microscopy measurements allow us to identify the microscopic origin of scattering in the Quantum Spin Hall edge states and reveals signatures of coexistence of topological with trivial edge states.

Nineteenth edition of the Physics symposia with "Topological materials: Insulators that lead and othe oddities" taught by Dr. Reyes Calvo Urbina,researcher at the CIC nanoGUNE Institute of the University of San Sebastian.

This colloquium is open to the public in general and especially to the students of the Degree in Physics of the UA.

The colloquium will take place on Thuesday, February 26, at 09:30 am, in the Board Room in Phase 2 of the Faculty of Sciences of the University of Alicante.

Given by: Carmen Rubio Verdú

Date and hour: Wednesday, 13 february 2019, 12:00h

Place: Polyvalent Room of the Department of Physics Applied, Faculty of Sciences, Phase 2 (2nd Floor)

Abstract:

Magnetic anisotropy is the preference of an atom’s spin to be aligned along a certain spatial direction. The Scanning Tunneling Microscope (STM) gives access to such individual magnetic moments through low-temperature Scanning Tunneling Spectroscopy (STS). In this talk I will show how both the magnetic moment, which defines the atomic spin S, and the interactions with the metallic substrate govern the spectral properties of single atoms and molecules.

A step further into the understanding of individual spins is to study their effect on a superconducting substrate. When a dilute amount of magnetic impurities is placed on top of a superconductor, they create a potential that locally distorts the Cooper pairs bath, while the mesoscopic superconducting characteristics remain unaltered [1]. The coupling of the impurity to the substrate create Yu-Shiba-Rusinov bound states [2-4], which can be studied down to the μeV energy range in STS measurements performed with superconducting STM tips.

In the search of new superconducting materials, we find Transition Metal Dichalcogenides as a new platform of crystalline layered materials that can be isolated down to the single-layer limit. In this regard, single-layer NbSe₂ [5] is envisioned as an ideal system for the study of superconductivity in two dimensions. We extracted the statistical distribution of the superconducting gap width and observed that it is well described by an asymmetric log-normal distribution which is indicative of emergent granularity in the presence of disorder, and reflects the multifractal nature of the superconductor eigenstates [6].

[1] P. W. Anderson, “Theory of dirty superconductors,” Journal of Physics and Chemistry of Solids, 11, 26 (1959).

[2] L. Yu, “Bound state in superconductors with paramagnetic impurities,” Acta Phys. Sin., 21, 75, (1965).

[3] H. Shiba, “Classical Spins in Superconductors,” Prog. Theo. Phys., 40, 435 (1968).

[4] A. I. Rusinov, “Superconductivity near a Paramagnetic Impurity,” ZhETF Prisma Redaktsiiu, 9, 146 (1968).

[5] M. M. Ugeda, et al., Nature Physics 12, 92 (2016).

[6] J. Mayoh and A. M. García-García, PRB 92, 174526 (2015).

Eighteenth edition of the Physics symposia with "Modeling light Nobel Prize in Physics 2018" taught by Íñigo Sola Larrañaga, Full Professor of the Department of Applied Physics of the University of Salamanca.

This colloquium is open to the public in general and especially to the students of the Degree in Physics of the UA.

The colloquium will take place on Thursday, February 7, at 11:30 am, in the Hall of Degrees. Rector Ramón Martin Mateo of the Faculty of Law of the University of Alicante.