Physics Education Mathematical Physics Department of Physics Faculty of Science Lund University   Electron correlations and electronic structure of correlated materials

Master Thesis Project (60 HP) on Hidden order in frustrated magnet Gd₃Ga₅O₁₂.

 

For further information please contact

Ferdi.Aryasetiawan@teorfys.lu.se (Room B305, Matematisk fysik) or

Claudio.Verdozzi@teorfys.lu.se (Room B306, Matematisk fysik)

 

The group

Ferdi Aryasetiawan

Rei Sakuma (postdoctoral fellow)

Fredrik Nilsson (doctoral student)

Tel. 046-222 9089, ferdi.aryasetiawan@teorfys.lu.se

ferdi.aryasetiawan@teorfys.lu.se

Our research interest is centered around developing theoretical schemes for describing the electronic structure of correlated materials from first-principles and investigating fundamental issues in electron correlations.

In the last few decades, many new materials with intriguing properties have been discovered and synthesised. Perhaps the most prominent of these is the elusive high-temperature superconductors, whose physical mechanism that gives rise to superconductivity still awaits theoretical explanation, despite almost thirty years of intensive research. Let alone a theoretical description, even the mediator of electron pairing (phonon in the case of conventional superconductors) is still under debate. Some of these new materials have found their way to practical applications. A class of magnetic layered materials possess an unusual property known as giant magneto resistance. When a magnetic field is applied on these materials along a certain axis, the electrical resistance changes drastically. Utilising this property, these magnetic materials are used as hard disk drives in our computers.

These materials, often referred to as strongly correlated materials, are characterised by the presence of 3d (transition metals) or 4f (lanthanides) elements and often magnetic. Valence electrons originating from 3d or 4f elements are different from s or p electrons in alkalis (Al, Na, Mg, etc. ) and semiconductors (Si, GaAs, Ge, etc.). In contrast to s or p electrons which are itinerant and  form a wide band, these 3d or 4f electrons are rather "shy": they are localised on their atomic sites with small overlap with neigbouring orbitals so that they form a narrow band. Since the electrons are rather localised, they interact strongly via the Coulomb interaction when they are on the same atomic site. This strong Coulomb interaction between localised electrons is one of the main ingredients responsible for the intriguing properties in correlated materials. Developing first-principles theories that account for this strong Coulomb interaction is an active field of research in condensed matter physics.

Fundamental topics of current interest

l  Merging first-principles and model approaches: Combining the GW method and the Dynamical Mean-Field Theory (DMFT) → GW+DMFT

l  How to determine the Hubbard U parameter from realistic band structure calculations.

l  Effects of non-locality and frequency-dependence of U.

l  Down folding the many-electron Hamiltonian to low-energy models.

l  Inclusion of long-range spin fluctuations in self-energy.

l  Many-electron orbital magnetic moment in solids

Current applications

l  Hubbard U for the 4f series (lanthanides), SmCo₅, transition metal oxides.

l  Electronic structure of SrVO₃ within the GW+DMFT method.

Literature     

Some recent articles:

 

1)       "Dynamical screening in La₂CuO₄",

Ph. Werner, R. Sakuma, F. Nilsson, and F. Aryasetiawan, Phys. Rev. 91, 125142 (2015).

 

2)       "Electronic structure of SrVO₃ within GW+DMFT",

R. Sakuma, Ph. Werner, and F. Aryasetiawan, Phys. Rev. B 88, 235110 (2013).

 

3)       "Ab initio calculations of the Hubbard U for the early lanthanides using the constrained random-phase approximation",

F. Nilsson, R. Sakuma, and F. Aryasetiawan, Phys. Rev. B 88, 125123 (2013).

 

4)       "First-principles calculations of dynamical screened interactions for the transition metal oxides MO (M=Mn, Fe, Co, Ni)",

R. Sakuma and F. Aryasetiawan, Phys. Rev. B 87, 165118 (2013).

 

5)       "Effects of momentum-dependent self-energy in the electronic structure of correlated materials",

T. Miyake, C. Martins, R. Sakuma, and F. Aryasetiawan, Phys. Rev. B 87, 115110 (2013).

 

6)       "Low-energy models for correlated materials: band width renormalization from Coulombic screening",

M. Casula, Ph. Werner, L. Vaugier, F. Aryasetiawan, T. Miyake, A. J. Millis, and S. Biermann, Phys. Rev. Lett. 109, 126408 (2012).

 

7)       "Self-energy and spectral function of Ce within the GW approximation",

R. Sakuma, T. Miyake, and F. Aryasetiawan, Phys. Rev B 86, 245126 (2012).

 

8)       "Self-energy calculation of the hydrogwn atom: importance of the unbound states",

R. Sakuma and F. Aryasetiawan, Phys. Rev. A 85, 042509 (2012).

 

9)       "Combined GW and dynamical mean-field theory: dynamical screening effects in transition metal oxides",

J. M. Tomczak, M. Casula, T. Miyake, F. Aryasetiawan, and S. Biermann, EPL 100, 67001 (2012).

 

10)   "Satellites, large doping- and temperature-dependence of electronic properties in hole-doped BaFe₂As₂",

P. Werner, M. Casula, T. Miyake, F. Aryasetiawan, A. J. Millis, S. Biermann, Nature Physics 8, 331 (2012).

 

11)   "GW Approximation with self-screening correction",

F. Aryasetiawan, R. Sakuma, and K. Karlsson, Phys. Rev. B 85, 035106 (2012).

 

12)   "GW calculations with spin-orbit coupling: Application to Hg chalcogenides",

R. Sakuma, C. Friederich, T. Miyake, S. Blugel, and F. Aryasetiawan, Phys. Rev. B 84, 085144 (2011).

 

13)   "Method for calculating the electronic structure of correlated materials from a truly first-principles LDA+U scheme",

K. Karlsson, F. Aryasetiawan, and O. Jepsen, Phys. Rev. B 81, 245113 (2010).

 

14)   "Realistic many-body models of manganese monoxide under pressure",

Jan M. Tomczak, T. Miyake, and F. Aryasetiawan, Phys. Rev B 81, 115116 (2010)

 

Selected articles:

 

"Satellites, large doping- and temperature-dependence of electronic properties in hole-doped BaFe₂As₂",

P. Werner, M. Casula, T. Miyake, F. Aryasetiawan, A. J. Millis, S. Biermann, Nature Physics 8, 331 (2012).

 

"Downfolded self-energy of many-electron systems",

F. Aryasetiawan, J. M. Tomczak, T. Miyake, and R. Sakuma, Phys. Rev. Lett. 102, 176402 (2009).

 

"Effective quasiparticle Hamiltonian based on Lowdin’s orthogonolization",

R. Sakuma, T. Miyake, and F. Aryasetiawan, Phys. Rev. B 80, 235128 (2009)

 

 "Ab initio procedure for constructing effective models for correlated materials with entangled band structure",

T. Miyake, F. Aryasetiawan, and M. Imada, Phys. Rev. B 80, 155134 (2009)

 

"Screened Coulomb Interaction in the Maximally Localized Wannier Basis",

T. Miyake and F. Aryasetiawan, Phys. Rev. B 77, 085122 (2008)

 

"Generalized Hedin's Equations for Quantum Many-Body Systems with Spin-Dependent Interactions",

F. Aryasetiawan and S. Biermann, Phys. Rev. Lett. 100, 116402 (2008)

 

"Frequency-dependent local interactions and low-energy effective models from electronic structure calculations",

Aryasetiawan F, Imada M, Georges A, Kotliar G, Biermann S and Lichtenstein AI, Phys. Rev. B 70, 195104 (2004)

 

"First-Principles Approach to the Electronic Structure of Strongly Correlated Systems: Combining the GW Approximation and Dynamical Mean-Field Theory", Biermann S, Aryasetiawan F and Georges A, Phys. Rev. Lett. 90, 086402 (2003).

 

Review articles:

 

"The GW method",

F. Aryasetiawan and O. Gunnarsson, Rep. Prog. Phys. 61, 237-312 (1998)

 

"First-principles calculations of the electronic structure and spectra of strongly correlated systems: the LDA+U method",

V. I. Anisimov, F. Aryasetiawan, and A. I. Lichtenstein, J. Phys.: Condens. Matter 9 767 (1997)

 

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Courses

Advanced Quantum Mechanics (FYST37), spring term

Electronic Structure Theory (FYST27), second part of autumn term

Updated 2015-06-01