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Martin Hoffmann

Dr. Martin Hoffmann

Univ.-Ass.

Curriculum Vitae

University assistent at Johannes Kepler University Linz, Austria

Project Researcher at Institute for Solid State Phsics, University of Tokyo, Japan

Research Associate at Leibniz Institute for Solid State and Materials Research Dresden, Germany

PhD student at Martin Luther University Halle-Wittenberg, Germany
Topic: "Multiple scattering theory for the description of defects in metallic alloys and oxide systems"
 

Diploma in Physics at Martin Luther University Halle-Wittenberg, Germany

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KUSSS Martin Hoffmann

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Awards

Scholarship of the International Max Planck Research School for Science and Technology of Nanostructures, Halle (Saale), Germany, 2011

Organized Conferences

Joint IMPRS/SFB Workshop on Nanoscience and -technology, Halle (Saale), Germany, 2013

Atomic-scale challenges in Advanced Materials (ASCAM) - Materials research: combing theory and experiments, Turku, Finland, 2015.

Research Interests

From the scientific point of view, I am interested in the broad field of materials research. I apply and develop numerical methods for the prediction of material specific properties, which are needed in nowadays technical applications.

At the moment, my personal focus is on various oxide materials because these materials class offers a broad spectrum of physical properties from magnets, insulators, metals over piezo electricity, magneto calorics, etc.  to their combinations - so called multiferroics. I am studying also other materials for specific applications - rare earth permanent magnets, graphene, and single atom memories.

These materails are studied with numerical methods based on density functional theory and model calculations like a classical Heisenberg model in Monte Carlo simulations. The most often used numerical codes are the Korringa-Kohn-Rostoker Green's function method (KKR) and the Vienna ab initio simulation package (VASP). This combination of numerical methods allows the intensive study of structural, electronic and magnetic properties. Typical antiquates can be easily calculated - density of states, band structure, magnetic moments - but also the phonon spectrum, the magnetic exchange parameters, and critical temperature are available.

One special feature of the KKR is the study of point defects in 3D or 2D systems. The understanding of the local microstructure around a defect and its macroscopic effect on the materials properties plays a crucial role in the design of materials tailored for a specific purpose in industries.

Publications
before 2018

see scientific profiles on

Tuning defect probability with epitaxial strain

Using first-prinicples calculations, we studied the effect of point defects and epitaxial strain in the complex oxide material Sr2FeMoO6 - abbriviated with SFMO (see right figure).

Various defects might show during the growth of bulk or thin films of SFMO. Oxygen vacancies can show up either in the xy plain or in z direction having a little bit different structural surroundings. Also other vacancies like missing Sr might be possible and should be considered in experimental studies. The most interesting defects are antisite defects - swaping of Fe with Mo and vice versa. We show that the defect probability of all defects varies with epitaxial strain. This opens the possibility to tune the amount of point defects inside thin films by the proper choice of a substrate with a specific lattice constant mismatch. The variations are sketched at the bottom of right-hand-side figure.

 

Bachelor and Master Theses

I am looking for bachelor and master students.

Have a look at the projects below or download the pdfs. Get in contact with me for further informations.

1. Disorder in Complex Oxides with Monte Carlo simulations

The topic of complex oxides covers a large group of materials showing  plenty of interesting or unique properties, from magnetism to ferroelectricity or magnetoelasticity, which are useful for various industrial applications. Here we are in particular interested in the microscopic ordering behavior of Sr2FeMoO6 (SFMO). This material is magnetic at room temperature and shows magnetoresistivity.

    
However, experimental measurements of the magnetization show discrepancies between thin films of SFMO and bulk samples, which are not yet fully understood. Disorder and lattice defects
might play a crucial role in influencing the material properties. Swapping Fe with Mo and vice versa represents an antiside defect (ASD). They can show different ordering behavior.

In this research project we are interested in the contribution of these ASD on the magnetic properties of SFMO. Therefore, we want to apply for such disordered systems a classical Heisenberg model based on realistic parameters calculated with first-principle methods. The topic can be adjusted to the needs of the student or the time frame of the Bachelor or Master thesis. Different complexity of programming can be realized.

2. Mg intermetallics and corrosion

Simulate structural, electronic, and thermodynamic properties via elaborate density functional theory (DFT) calculation. This project includes  industrial collaboration with RAUCH Furnace Technology GmbH producing melting equipment for Mg casting solutions. 

Interesting Scientific Findings

What happens in the materials research community?

Plastics made of corn starch: Advanced Science News
- original paper (Sep 2018): https://doi.org/10.1002/pola.29237

Possible printed paper electronics: Advanced Scicence News
- original paper (May 2018): https://doi.org/10.1002/adma.201800062

Interesting Financial Funding

Since there is always the problem of scientific funding, I want to collect and show other potential sources, which might be not very known but still interesting for students and fellow researchers. 

THEODOR KÖRNER FONDS Link (research projects with specific connection to Austria)

ProScientia Link (I have no own expieriences with that funding organization)

 

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