Data: 17/10/2024 (quinta-feira)
Horário: 11:00 h
Local: sala 201 da torre antiga
Caros estudantes e docentes,
O próximo seminário do grupo de matéria condensada ocorrerá com a apresentação do
doutorando M. A. Habitzreuter (UFRGs). O título e abstract seguem abaixo.
Tarik em nome da comissão organizadora.
Ps: Agora com cafézinho e biscoito!
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Título: Specific heat and density anomalies in the Hubbard model
Anomalous thermal properties of materials are an intense source of research in different realms of physics. An anomalous thermal expansion coefficient can be found in complex fluids such as water, as well as in solids such as the heavy fermion compound CeRu2Si2 and the spin-liquid candidate κ-(BEDT-TTF)2Cu2(CN)3. The Invar Fe-Ni alloy is also interesting in this regard, displaying a very low thermal expansion, with recent measurements highlighting the role of electrons in this effect.
Another surprising phenomenon is a non-monotonic behavior of the specific heat as a function of doping measured in novel experiments, which is not much explored in the literature. In our work, we perform finite-temperature quantum Monte Carlo simulations of the Fermi-Hubbard model to understand the role of electronic interactions on these thermal properties.
We found that, due to strong correlations, the specific heat presents a three-peak structure as a function of filling, with local minima between them. This effect can be explained by a decomposition of kinetic and potential contributions to the specific heat.
Moreover, analyzing the kinetic contribution in momentum space, we show a density anomaly, detected with the thermal expansion coefficient. These momentum-space quantities are accessible using cold-atoms experiments.
Finally, we map the location of these phenomena and connect the thermal expansion anomaly with the well-known Seebeck coefficient change of sign. Our results show a connection between thermal and transport properties and provide a new perspective to analyze the Seebeck change of sign.