May 06, 2023
Electronic Structure Theory (Ali Alavi)

The Electronic Structure Theory department develops ab initio methods for treating correlated electronic systems, using quantum chemistry and quantum Monte Carlo methods. These include full configuration interaction quantum Monte Carlo (FCIQMC), density matrix renormalization group methods, many-body perturbation and coupled-cluster theories. Such methodologies are needed to accurately solve physical systems in which the electronic wavefunctions are strongly multiconfigurational, and for which a high degree of basis-set flexibility is also necessary. Recent methodological progress has been the implementation of spin-adapted FCIQMC, which allows the efficient simulation of low-spin open-shell systems. Examples of such systems currently under investigation are polynuclear transition metal clusters, and in the solid-state, cuprates and nickelates. We are also pursuing transcorrelated (TC) methods, in which the electronic wavefunction is factorised using real-space Jastrow factors, which give rise to effective non-hermitian hamiltonians. TC wavefunctions can dynamical correlations and cusp conditions via explicit 2-body electron-electron and 3-body electron-electron-nuclear terms in the Jastrow factor, whilst static correlation is efficiently described by FCIQMC. Our aim is to extend the TC method towards strongly correlated systems allowing for an accurate and efficient description of both the strong dynamical and static correlations typically present in such systems. more
Solid State Spectroscopy (Bernhard Keimer)

Keimer's department studies the structure and dynamics of highly correlated electronic materials by spectroscopic and scattering techniques. Topics of particular current interest include the interplay between charge, orbital, and spin degrees of freedom in transition metal oxides, the mechanism of high-temperature superconductivity, and the control of electronic phase behavior in metal-oxide superlattices. High-quality single crystals and epitaxial thin-film structures are synthesized in close collaboration with other research groups at the Institute. Experimental techniques being used include elastic and inelastic x-ray and neutron scattering, neutron spin-echo spectroscopy, Raman scattering, and wide-band spectral ellipsometry. The department operates several beamlines at the research reactor FRM-II in Garching and at the PETRA-III synchrotron in Hamburg. The department also comprises a theory group, and it collaborates closely with the theory departments in the Institute on the analysis and interpretation of spectroscopic data. more
Nanoscale Science (Klaus Kern)

Research efforts in the Nanoscale Science department are centered on nanometer-scale science and technology with a focus on the bottom-up paradigm. The aim of the interdisciplinary research at the interface between physics, chemistry and biology is to gain control of materials at the atomic and molecular level, enabling the design of systems and devices with properties determined by quantum behavior on one hand and approaching functionalities of living matter on the other hand. more
Nanochemistry (Bettina Lotsch)

Research in the Nanochemistry Department is geared towards the rational synthesis of new multifunctional materials with engineered properties by combining the tools of solid-state chemistry, molecular chemistry, and nanochemistry. We aim at creating function from both atomic-scale structure and nanoscale morphology, with a strong emphasis on exploring structure-property-activity relationships in functional materials based on advanced diffraction, spectroscopic and microscopic techniques. Specifically, we invoke concepts of classical solid state synthesis, "soft chemistry" and directed self-assembly to develop molecular materials, porous frameworks, functional inorganic and quantum materials, as well as photonic nanostructures for (photo)electrochemical energy conversion, electrochemical energy storage, and sensing. more
Solid State Quantum Electronics (Jochen Mannhart)

Induced by quantum mechanical phenomena, novel electron systems with fascinating potential can be created in thin-film-based quantum materials. Many of these systems have outstanding properties not otherwise found in nature. The design, growth, and exploration of quantum devices driven by such systems are the focus of the Solid State Quantum Electronics department.
We fabricate these devices using advanced epitaxial growth techniques such as thermal laser epitaxy, which we are pioneering with our spin-off company ‘Epiray’.
Complex compounds are deposited with atomic-layer precision and patterned on the nanoscale. Our research aims to unravel the fundamental physics of mesoscale quantum devices operating at the edge of the quantum world. We are committed to understanding and exploring the devices’ potential to surpass the hitherto accepted fundamental limits of energy-harvesting devices and electronics. more
Quantum Many-Body Theory (Walter Metzner)

Electronic properties of solids are analyzed and computed in Metzner's department with a main emphasis on systems where electronic correlations play a crucial role, such as cuprate high temperature superconductors and other transition metal oxides. Besides symmetry-breaking phase transitions leading to magnetism, orbital and charge order, or superconductivity, correlations can also cause electron localization and many other striking many-body effects not described by the independent electron approximation. Our research focuses in particular on unconventional superconductors and topological quantum materials. Besides bulk properties of one-, two- and three-dimensional systems, also surface states of topological insulators and semimetals, as well as problems with a mesoscopic length scale such as quantum dots and quantum wires are being studied. The correlation problem is treated by various numerical and field-theoretical techniques: exact diagonalization, density matrix renormalization group, dynamical mean-field theory, and functional renormalization group. Modern quantum many-body methods are not only being applied, but also further developed within our group. more
Quantum Materials (Hidenori Takagi)

Entanglement of electrons (electron correlations) in solids, in combination with details of the crystal lattice structure, produce a surprisingly rich variety of electronic phases, that are liquid, liquid-crystal and crystalline states of the charge and spin degrees of freedom. These complex electronic phases and the subtle competition among them very often give rise to novel functionality. The department will be studying these interesting novel phases in transition metal oxides and related compounds where the narrow d-bands, which give rise to strong electron correlations, in combination with the rich chemistry of such materials provides excellent opportunities for new discoveries. The goal of this research will be to hunt for new materials exhibiting exotic electronic states of matter, showing phenomena such as superconductivity, quantum spin liquid and metal-insulator transition, and to explore them with advanced measurement techniques to unveil the physical mechanisms that could be drivers of potentially highly desirable functionality. more
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