THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:
Dirac Electrons in Two Dimensional Crystals 
Sergio E. Ulloa
Department of Physics and Astronomy and Nanoscale and Quantum Phenomena Institute
Ohio University
Abstract:
Graphene, a monoatomic layer of carbon, is perhaps the simplest and most easily available material where electrons behave as massless Dirac particles. Apart from its many promising technological applications, the study of graphene (and other layered materials) has opened a number of interesting theoretical questions: the microscopic crystalline structure requires an additional degree of freedom (the pseudo spin) that gives rise to effects such as the Klein paradox or Veselago electron lenses.
This relativistic dynamics is further emphasized by the presence of an interesting relativistic effect: the spin-orbit interaction (SOI), which is present in materials that lack inversion symmetry in the lattice structure or arises from external or interfacial fields that break spatial symmetries. Although SOI is weak in natural graphene, it can be enhanced by local hybridizations with impurities by manipulation of substrates or applied gates. Moreover, the effective exchange interactions between magnetic impurities in this and related 2D materials exhibit interesting behavior.
In this talk, I will present our studies of electronic transport and Kondo screening in graphene, as well as the role of intrinsic SOI in transition metal dichalcogenides in mediating RKKY interactions.
Date: August 21, 2017 – (monday) – Place: Sala 212 – Auditótio do Departamento de Física – Time: 10 horas
The Physics Graduate Program invites everyone to:
Defense of Doctoral Thesis
Eduardo Muller dos Santos
INCERTEZA E INFORMAÇÃO QUÂNTICA NO MODELO DE SUPERRADIÂNCIA DE DICKE
Defense Committee:
Prof. Dr. Eduardo Inacio Duzzioni – (president – UFSC/FSC)
Profª. Drª. Liliana Sanz De La Torre – (external member – UFU/IF)
Prof. Dr. Luis Guilherme de Carvalho Rego – (external member – UFSC/FSC)
Prof. Dr. Bruno Gouvêa Taketani – (membro titular – UFSC/FSC)
Prof. Dr. Kahio Tiberio Mazon – (supplementary member – UFSC/FSC)
Date: August 18, 2017 – friday – Times: 3:00 pm – Place: Sala 212 – Auditório do Departamento de Física
THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:
Thermalization in black-body radiation and application to the Lipkin-Meshkov-Glick model.
Massimo Ostilli
Pós-doutorando/UFSC
Abstract:
In a recent work, we have derived simple Lindblad-based equations for the thermalization of systems in contact with a thermal reservoir. Here, we apply these equations to the Lipkin-Meshkov-Glick model (LMG) in contact with a blackbody radiation and analyze the dipole matrix elements involved in the thermalization process. We find that the thermalization can be complete only if the density is sufficiently high, while, in the limit of low density, the system thermalizes partially, namely, within the Hilbert subspaces where the total spin has a fixed value. In this regime, and in the isotropic case, we evaluate the characteristic thermalization time analytically, and show that it diverges with the system size in correspondence of the critical points and inside the ferromagnetic region. Quite interestingly, at zero temperature the thermalization time diverges only quadratically with the system size, whereas quantum adiabatic algorithms, aimed at finding the ground state of same system, imply a cubic divergence of the required adiabatic time.
Date: August 11, 2017 – (friday) – Place: Sala 212 – Auditório do Departamento de Física – Time: 10h10min
