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Engineering Physics

Prof. Rudolf Gross

Research Field

The research activities of the Walther-Meißner-Institute are focused on low temperature solid-state and condensed matter physics. The research program is devoted to both fundamental and applied research and also addresses materials science, thin film and nanotechnology aspects. With respect to basic research the main focus of the WMI is on

  • superconductivity and superfluidity,
  • magnetism, spin transport, and spin caloritronics,
  • quantum phenomena in mesoscopic systems and nanostructures,
  • and the general properties of metallic systems at low and very low temperatures.

The WMI also conducts applied research in the fields of

  • solid-state quantum information processing systems,
  • superconducting and spintronic devices,
  • oxide electronics,
  • multi-functional and multiferroic materials,
  • and the development of low and ultra low temperature systems and techniques.

With respect to materials science, thin film and nanotechnology the research program is focused on

  • the synthesis of superconducting and magnetic materials,,
  • the single crystal growth of oxide materials,
  • the thin film technology of complex oxide heterostructures including multi-functional and multiferroic material systems,
  • the fabrication of superconducting, magnetic, and hybrid nanostructures,
  • and the growth of self-organized molecular ad-layers.

The WMI also develops and operates systems and techniques for low and ultra-low temperature experiments. A recent development are dry mK-systems that can be operated without liquid helium by using a pulse-tube refrigerator for precooling. Meanwhile, these systems have been successfully commercialized by the company VeriCold Technologies GmbH at Ismaning, Germany, which meanwhile has been acquired by Oxford Instruments. As further typical examples we mention a nuclear demagnetization cryostat for temperature down to below 100µK, or very flexible dilution refrigerator inserts for temperatures down to about 20mK fitting into a 2inch bore. These systems have been engineered and fabricated at the WMI. Within the last years, several dilution refrigerators have been provided to other research groups for various low temperature experiments. The WMI also operates a helium liquifier with a capacity of more than 150.000 liters per year and supplies both Munich universities with liquid helium. To optimize the transfer of liquid helium into transport containers the WMI has developed a pumping system for liquid helium that is commercialized in collaboration with a company.

Address/Contact

Walther-Meißner-Straße 8
85748 Garching b. München
+49 89 289 14202
Fax: +49 89 289 14206

Members of the Research Group

Professor

Office

Scientists

Other Staff

Teaching

Course with Participations of Group Members

Titel und Modulzuordnung
ArtSWSDozent(en)Termine
jDGKK
Zuordnung zu Modulen:
WS 0.1
Leitung/Koordination: Erb, A.
einzelne oder verschobene Termine

Offers for Theses in the Group

All-Electrical Magnon Transport in Magnetically Ordered Insulators

Angular momentum transport in magnetically ordered insulators is carried by magnetic excitation quanta in contrast to magnetic conductors, where mobile charge carrier also carry angular momentum. In magnetically ordered insulator/normal metal hybrids it is possible to study the transport of angular momentum by all-electrical means via the spin Hall and inverse spin Hall effect in the normal metal. The focus of this project is the investigation of possibilities to manipulate the angular momentum transport in the magnetically ordered insulator by electrical means and by finite size effects. In addition, another goal is the enhancement of the sensitivity of the currently existing measurement setup and the realization of new measurement protocols in hard- and software.

An ambitious master student with good analytical skills is required to carry out these experiments on all-electrical magnon transport. One part of the thesis is the fabrication of nanometer sized devices for the experiments via electron beam lithography and UHV sputtering. The properties of these devices will be analyzed using magnetotransport experiments in superconducting magnet cryostats. Another important aspect is the realization of more sophisticated measurement methods, aiming for a enhancement in sensitivity, a better signal-to-noise ratios and a higher versatility of the measurement protocols

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
High-field magnetotransport in an organic superconductor in proximity to the quantum spin-liquid Mott-insulating state

One of topical issues of the modern condensed matter physics is the interplay between superconducting and insulating instabilities of the normal metallic state in materials with strong electronic correlations. Organic metals and superconductors, thanks to their high crystal quality, simple conduction bands, and a great diversity of electronic states, offer a perfect laboratory for studying fundamental problems of the correlated electron physics. A member of the κ-(ET)2X family to be studied in this Master thesis is believed to represent a novel state of matter, quantum spin liquid at ambient pressure. Under a moderate pressure of about 3 kbar the material becomes metallic and superconducting.

The aim of the work is to trace the evolution of the electronic properties, particularly, of correlation effects, in close proximity to the metal-insulator phase boundary. The position with respect to the phase boundary will be precisely tuned by applying quasi-hydrostatic pressure. Magnetoresistance and especially its quantum oscillations in strong magnetic fields will be used to probe the electronic properties of the system. Observation of the oscillations requires sufficiently low temperatures which will be achieved by use of a 3He cryostat (down to 0.4 K) and of a 3He-4He dilution refrigerator (down to below 100 mK). A part of the experiment will be done at the European Magnetic Field Laboratory in steady fields up to 30 T or in pulsed fields up to 80 T. The experimental results will be analyzed in comparison with recent theoretical predictions of correlation effects and violations of the Fermi-liquid behavior in proximity to the spin-liquid Mott-insulating state.

Physics: Correlated electron systems; metal-insulator transition; magnetic quantum oscillations; unconventional superconductivity.

Techniques: Strong magnetic fields; high pressures; cryogenic (liquid 4He; 3He; dilution fridge) techniques; high-precision magnetoresistance measurements.

Contact person: Mark Kartsovnik (mark.kartsovnik@wmi.badw.de)

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Interaction between magnetic and conducting subsystems in molecular antiferromagnetic superconductors

Multifunctional materials combining nontrivial conducting and magnetic properties are one of hot topics in the modern condensed matter physics. Prominent examples are charge transfer salts of the organic donor BETS with anions containing a transition metal. They represent perfect multilayer structures of conducting and magnetic subsystems separated on a nanometer scale. The interplay between the two subsystems results in a variety of electronic and magnetic ground states depending on subtle chemical substitutions as well as on external magnetic field and pressure. The goal of this master thesis is a quantitative study of the interaction between the itinerant electrons and localized spins in the antiferromagnetic superconductors (BETS)2FeX4 with X = Cl, Br. To this end, comparative measurements of quantum oscillations in the magnetoresistance and magnetization will be carried out at strong magnetic fields, at temperatures down to 0.4 K. The results will be analyzed in terms of the exchange field dependent spin-splitting effect in a quasi-two-dimensional metal.

Physics: Correlated electronic systems; magnetic ordering and superconductivity; magnetic quantum oscillations.

Techniques: Strong magnetic fields; magnetotransport; magnetic torque; cryogenic (liquid 4He and 3He) techniques.

Contact person: Mark Kartsovnik (mark.kartsovnik@wmi.badw.de)

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Manipulating Spin Waves by Spin-Orbit Torques

The field of magnonics deals with exploiting the collective spin dynamics (spin waves) of magnetically ordered materials for computational purposes. Efficient and scalable schemes for controlling spin waves in thin film ferromagnets thus have large application relevance. The magnetic torques arising due to the spin-orbit interaction allow to control spin waves by electric currents and acoustic waves at GHz frequencies. We are particularly interested in a spatially-resolved study of the interaction of spin waves with acoustic and current-induced torques in nanopatterned devices with application potential for spintronics.

We are looking for a talented and highly motivated master student who is interested in joining our spin dynamics project. During your thesis, you will use state-of-the-art nanolithography and thin film deposition tools to fabricate hybrid devices that allow for the interaction of spin waves with electrical currents and acoustic waves. You will study spin waves in these devices using optical and microwave spectroscopy methods.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Topological magnetic phases in thin film heterostructures

The broken inversion symmetry at the interface of thin film ferromagnets and normal metals with strong spin-orbit coupling can give rise to chiral magnetic order. These chiral magnetic materials show exotic magnetic properties such as a skyrmion lattice phase and have strong application potential for future spintronic devices. For these applications, a detailed understanding of the magnetization dynamics in these materials is required. The goal of this master thesis is to fabricate such thin film multilayer structures using sputter deposition techniques and analyze their dynamic magnetic properties using broadband ferromagnetic resonance spectroscopy.

We are looking for a highly motivated master student to carry out these experiments on interfacial effects in metallic multilayers. The thesis work will be split up into of the fabrication of these multilayer structures using UHV sputter deposition systems and determining their magnetic properties by broadband ferromagnetic resonance spectroscopy and SQUID magnetometry.

suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Gross
Tunneling- und Raman-spectroscopy in cuprate-superconductors
In superconductors on CuO2 basis (cuprates) the fundamental questions as to the relevant energy scales such as the gap in the superconducting state or the pseudo-gap above the superconducting transition temperature Tc as well as their interrelation remain a tantalizing open problem. This is highlighted by the discrepancies between the different types of spectroscopies sensitive to electronic properties such as photoemission, tunneling, infrared of Raman spectroscopy. Tunneling spectroscopy has enough resolution to demonstrate the spatial variation of the energy scales. Raman spectroscopy shows a dependence of the energy scales on impurities and strain. For addressing this problem it is intended to study tunneling and Raman spectra at the identical location of selected samples and to analyze the data simultaneously. The analysis will be performed in collaboration with theorists at Stanford University. The work includes a thorough introduction to spectroscopy as well as low-temperature and ultra-high vacuum (UHV) methods.
suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Hackl
Study of the energy scales of cuprate-superconductors as a function of applied pressure
Superconductors on CuO2 basis (cuprates) are characterized by a plethora of phases and instabilities including superconductivity. Their interrelation is considered crucial for understanding the material class, in particular high-Tc superconductivity. For accessing the various phases one usually varies the doping but, concomitantly, the crystal and /or defect structure changes. Alternatively, the doping level can be varied using hydrostatic pressure allowing one to use the very same sample for at least a limited doping range. The related volume change is considered less problematic. It is intended to study the relevant energy scales of the accessible phases by inelastic light (Raman) scattering in a diamond anvil cell (DAC). The pressure range of our DAC is approximately 20 GPa being sufficient for all cuprates. During the Master’s thesis appropriately doped samples shall be prepared using a tested annealing protocol. The samples have to be mounted in the DAC and studied via Raman scattering at various applied pressure values. The work includes a thorough introduction to the physics of the cuprates, as well as spectroscopy, low-temperature, and high-pressure methods.
suitable as
  • Master’s Thesis Condensed Matter Physics
  • Master’s Thesis Applied and Engineering Physics
Supervisor: Rudolf Hackl

Current and Finished Theses in the Group

Quantum Memory with Optimal Control
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
Spin Seebeck effect: a powerful probe of magnon properties in compensated ferrimagnets
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Rudolf Gross
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