Realistic theory of electronic correlations in nanoscopic systems

Schüler, Malte; Barthel, Stefan; Wehling, T. O.; Karolak, M.; Valli, Angelo; Sangiovanni, Giorgio

doi:10.1140/epjst/e2017-70049-3

Cited by 28 publications

(31 citation statements)

References 124 publications

(233 reference statements)

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“…It is therefore very interesting to address this issue in our inhomogeneous system where the local density changes as we move from the center to the edge of the system. We solve the model using a real-space dynamical meanfield theory (DMFT) [28][29][30][31] approach, which has been previously used to study inhomogeneous systems, such as cold atoms [31][32][33], and nanostructures [34][35][36], including isolated graphene nanoflakes [12]. In the homogeneous case DMFT approximates the lattice self-energy of the interacting many-body problem with a local, momentumindependent, self-energy which, however, retains the full frequency dependence which allows to capture non-trivial quantum correlations characteristic of strongly correlated systems [28].…”

Section: Model and Methodsmentioning

confidence: 99%

Inducing and controlling magnetism in the honeycomb lattice through a harmonic trapping potential

et al. 2020

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We study strongly interacting ultracold spin-1/2 fermions in a honeycomb lattice in the presence of a harmonic trap. Tuning the strength of the harmonic trap we show that it is possible to confine the fermions in artificial structures reminiscent of graphene nanoflakes in solid state. The confinement on small structures induces magnetic effects which are absent in a large graphene sheet. Increasing the strength of the harmonic potential we are able to induce different magnetic states, such as a Néel-like antiferromagnetic or ferromagnetic states, as well as mixtures of these basic states. The realization of different magnetic patterns is associated with the terminations of the artificial structures, in turn controlled by the confining potential.

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Section: Model and Methodsmentioning

confidence: 99%

Inducing and controlling magnetism in the honeycomb lattice through a harmonic trapping potential

et al. 2020

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“…Referring to several concrete examples the authors discuss how these two routes can be combined. Schüler et al [9] review method developments and applications of theoretical approaches for the realistic description of the electronic and magnetic properties of nanostructures with correlated electrons. The implementation of a flexible interface between DFT and a variant of DMFT suitable for the simulation of complex correlated structures is explained and illustrated.…”

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confidence: 99%

Dynamical mean-field approach with predictive power for strongly correlated materials

Vollhardt

Lichtenstein

2017

Eur. Phys. J. Spec. Top.

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Electronic correlations in solids are known to lead to the emergence of novel, unexpected phenomena, which are not only of interest for fundamental research but also have a great potential for technological applications. Hence there is a great need for appropriate theoretical techniques that allow for an accurate exploration of correlated electron materials. For a long time first-principles investigations of correlated materials were out of reach. During that time the electronic properties of solids were investigated by two essentially separate communities, one employing density functional theory (DFT), the other studying model Hamiltonians using many-body techniques.Here the Dynamical Mean-Field Theory (DMFT), whose development started more than 25 years ago, opened new perspectives. In contrast to single-particle theories the mean-field of the DMFT is energy dependent, i.e., dynamical. Thereby the local quantum fluctuations on the impurity due to the bath are fully taken into account. The only approximation of the DMFT is the neglect of spatial fluctuations. Thus DMFT provides a comprehensive theoretical framework for the investigation of correlated lattice models and can describe, for example, fluctuating moments, the renormalization of quasiparticles, and the correlation induced spectral-weight transfer between low-and high-energy states.To go beyond model studies and investigate real materials with strongly correlated electrons, the combination of DFT in the local density approximation (LDA) with the many-body DMFT, the so-called "LDA+DMFT" approach, was initiated 20 years ago. Starting from band structure theory, local correlations are taken into account by interaction terms which can be parametrized in particular by the Hubbard U and the Hund's rule coupling J. The resulting coupled, self-consistent LDA+DMFT equations have to be solved numerically, usually by employing quantum Monte-Carlo techniques.a

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“…17 In the latter, the interactions are highly affected by the electronic structure of materials, introducing a non-trivial ingredient defeating the traditional formulation in terms of analytical solutions obtained for model Hamiltonians. 18 What is worse, even at the level of approximation based on model Hamiltonians, finding exact analytical solutions is limited to few situations. In that sense, a general approach to the description of quantum devices in complex regimes must include a numerical framework allowing for a realistic description of materials, so Density Functional Theory seems to be a promising route to be explored.…”

Section: Transport In Quantum Dots and Novel Technologiesmentioning

confidence: 99%

“…As correlations are highly affected by the electronic structure of materials, an adequate procedure is expected to combine precise band structure calculations with many-body tools for simulating interacting electrons. 17,18 While density functional theory undoubtedly fulfils the first requirement, the second part of the desired approach is still in progress. Recently, works combining ab-initio calculations with Dynamical Mean Field Theory (DMFT), such as LDA-DMFT, have achieved good performance in low dimensional devices and currently there are some implementations available.…”

Section: The Kohn-sham Anderson System and The Hybrid Self-consistentmentioning

confidence: 99%

“…Recently, works combining ab-initio calculations with Dynamical Mean Field Theory (DMFT), such as LDA-DMFT, have achieved good performance in low dimensional devices and currently there are some implementations available. 17,18,110 Nonetheless, there is much work to be done on the problem of accounting for non-local effects and, also, out-of-equilibrium regimes. From this perspective, numerical algorithms based on the renormalization-group, which yield essentially exact solutions of various strongly correlated systems, offer an alternative route.…”

Section: The Kohn-sham Anderson System and The Hybrid Self-consistentmentioning

confidence: 99%

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Density-functional theory for single-electron transistors

Zawadzki¹

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I would like to open my huge list of acknowledgements by thanking my advisor, Prof. Luiz Nunes Oliveira. Luiz, with his knowledge, patience and kindness is one of the most special human beings I have ever met in my life. Along the past ten years, Luiz has not only taught me physics, he also showed me the value of learning. With his wizard tricks to make complicated things easy, Luiz inspired me the desire to learn to share knowledge with other people. I consider him more than a mentor: an academic father without whom I would not have achieved most of the victories I had. I feel fortunate to had the opportunity to start my academic journey under his supervision and I wish one day I could make him proud to have mentored me. Alongside with Luiz, my co-advisor, Prof. Irene D'Amico has a special place in my acknowledgements list. Irene is an example of researcher, advisor and person. With her ability of multitasking, Irene was able not only to advise me in research, but also to showed me the importance of having a balanced life. She is my academic mother, always careful with my well being and my progress as a PhD student. We probably will never forget that sleepless nights of March, the relief in the end, and our dream to celebrate together with maracuja caipirinhas. Irene was the major responsible for the little success I achieved this year. For me, Irene represents the figure of strong woman in Physics and I would like to thank her very much for receiving me as a supervisee and for being a supportive friend during the past four years. Besides the support of my academic parents, I am fortunate to have my family. Andressa, my beloved twin sister, is an inspiration for me: I consider her the copy "which worked". I have to confess that, sometimes, I could rely only on her success to be happy by myself. As all siblings, we had our fights and controversies, but we were always there for each other. Only we know the difficulties we had in our childhood and teenage and the meaning of reaching a PhD level. Our ties extend frontiers. I am really proud to see her now as a post-doc in Copenhagen after all the mess that happened last year. I am grateful for the few times she let me share my fears and made me calm. Equally important was the support of my mother, Jane and my aunt, Lelzinda. Zinda was one of the most important characters of my journey in science, always encouraging me and Andressa to study and to follow our dreams.

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Realistic theory of electronic correlations in nanoscopic systems

Cited by 28 publications

References 124 publications

Inducing and controlling magnetism in the honeycomb lattice through a harmonic trapping potential

Inducing and controlling magnetism in the honeycomb lattice through a harmonic trapping potential

Dynamical mean-field approach with predictive power for strongly correlated materials

Density-functional theory for single-electron transistors

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