Optical spectroscopy study on Ir-based magnetic materials

The 5d transition-metal oxides such as iridates are currently in the focus of condensed matter physics as they are promising candidates for the realization of novel quantum states like the quantum spin liquid state. The exotic physical properties are due to the complex interplay between strong spin-orbit coupling, electronic correlations, and crystal field.
This project focuses on honeycomb-type iridates and hexagonal perovskite-type iridates with mixed valence. Their electronic properties and lattice dynamics will be studied by optical spectroscopy. We will also apply external pressure by diamond anvil cells to induce structural or electronic phase transitions, and the emerging novel high-pressure phases will be characterized in terms of the low-energy excitations.

Please also see the project description (PDF).

ContactProf. Dr. Christine Kuntscher, Room 361 (Physics North Building), Phone: (0821) 598-3315



Optical properties of transition-metal dichalcogenides

Transition-metal dichalcogenides MX2, where M is a transition metal (Nb, Mo, Ti etc.) and X is a chalcogen atom (S, Se or Te) display several interesting electronic phases including charge density wave, superconductivity, and Weyl semimetal with exotic physical properties. Each of these phases has characteristic optical properties, which can be probed by infrared spectroscopy.
The aim of this Master project is to characterize various transition-metal dichalcogenides in terms of their optical properties by temperature-dependent reflectivity measurements. The results give valuable insight into the charge dynamics, lattice vibrations, and interband transitions in these materials.

Please also see the project description (PDF).

ContactProf. Dr. Christine Kuntscher, Room 361 (Physics North Building), Phone: (0821) 598-3315



Analysis of crack pattern development during pyrolysis of carbon fiber reinforced plastic for manufacturing of ceramic matrix composites (C-C/SiC)

Ceramic matrix composites like C-C/SiC combine the high thermal stability of conventional ceramics with a high fracture toughness, damage tolerance and thermal shock resistance, which makes them ideal for applications in extreme environments.
The matrix material of carbon fiber reinforced plastics is converted into porous carbon during pyrolysis. This induces crack formation within the matrix. The cracks then serve as infiltration paths for liquid silicon (Liquid Silicon Infiltration, LSI). Here, the crack pattern significantly influences the properties of the resulting composite.
In this work, an experimental setup for acoustic emission analysis during pyrolysis will be tested and optimized regarding its transfer properties. Subsequently, samples with different material systems will be tested in this setup with the goal of characterizing the crack formation and identifying influencing factors.

Contact: Bastian Brueck, Room 376 (Physics North Building), 

Phone: (0821) 598-3422



Testing of a gold evaporation cryostat

To obtain quantitative reflectivity spectra of a material as a function of temperature, the measurement of a perfect reference is mandatory. Such a perfect reference is realized by the intensity reflected from the gold-coated sample under investigation, where the gold coating is achieved by in-situ gold evaporation.
Within this Master project a gold evaporation cryostat will be tested in our Fourier-transform infrared spectrometer. After the successful testing, temperature-dependent reflectivity measurements on transition-metal dichalcogenides will be carried out.

Please also see the project description (PDF).

ContactProf. Dr. Christine Kuntscher, Room 361 (Physics North Building), Phone: (0821) 598-3315



Synthese von Mangan-Ferrit Nanopartikeln aus wässriger Lösung und deren mikroskopische und magnetische Charakterisierung

Im Rahmen dieser Masterarbeit sollen Manganferit-Nanopartikel aus wässriger Lösung über das "SPOP"-Verfahren (Spezifische produktorientierte Präzipitation) in Kooperation mit dem Institut für Geo- und Umweltwissenschaften der LMU synthetisiert werden. Die Partikel werden elektronenmikroskopisch und magnetisch charakterisiert.
Das Ziel ist die Entwicklung von magnetisch aktiven Partikeln, die sich als Suszeptormaterial für den induktiven Energieeintrag aus magnetischen Wechselfeldern in verschiedene Werkstoffe (z.B. Polymere) einsetzen lassen. Der Einfluss von Syntheseparametern und chemischer Zusammensetzung auf die physikalischen Eigenschaften soll systematisch untersucht werden.

KontaktDr. Aladin Ullrich, Raum 364 (Nordgebäude), Telefon: (0821) 598-3215



Gezielte Oxidation von Eisenoxidnanopartikeln während der Synthese aus Eisenoleat-Precursor durch Zugabe von Sauerstoff in die Schutzgasatmosphäre

Im Rahmen dieser Arbeit werden Nanopartikel aus einem Metalloleat-Precursor synthetisiert. Der Precursor wird dabei in einem hochsiedenden Lösungsmittel bei >300°C thermisch zersetzt. Dabei wird durch eine Schutzgasatmosphäre die Oxidation des Lösungsmittels verhindert. Jedoch entstehen bei der Zersetzung reduzierend wirkende Nebenprodukte, so dass ein Teil des ursprünglich dreiwertigen Eisens in den Nanopartikeln als Fe2+ vorliegt. Dieses wirkt sich insbesondere auf die magnetischen Eigenschaften der Partikel aus.
Das Ziel der Arbeit besteht darin, während oder nach der Partikelsynthese eine oxidierende Umgebung zu schaffen, um den Oxidationszustand des Eisens in den Partikeln zu kontrollieren. Die Analyse der Partikel erfolgt u.a. mittels TEM, XRD, SQUID und EELS.

KontaktDr. Aladin Ullrich, Raum 364 (Nordgebäude), Telefon: (0821) 598-3215



Magnetic field dependence of the critical temperature behavior as a function of the F1-layer thickness in S/F1/F2-type triplet spin-valves

• Preparation of samples
• Measurements of the critical temperature in different magnetic fields in the low temperature laboratory
• Measurements of the magnetoresistance for different F1-film thicknesses at fixed temperature in the low temperature laboratory
• Measurement of the film thicknesses by Rutherford Backscattering Spectroscopy

Ansprechpartner: Daniel Lenk, Raum 375 Nord, Telefon: (0821) 598-2111



Examination of the chemical mechanism during thermal treatment of carbon fiber PAN precursors

By synthesis of isotopically labelled PAN precursors (2H, 15N, 13C) including their copolymers (with methylacrylate, itaconic acid?) and examination of the structural changes of them during thermal treatment by means of IR and NMR spectroscopy, DSC measurement and TG/GC/MS analysis the mechanism and elemental chemical reactions for the formation of efficient carbon fibers is worked out.
The knowledge about the detailed reaction pathways leading to most-efficient final carbon fiber material is still very limited. Thus, it is extremely difficult for carbon fiber producers (e. g. SGL Carbon) to systematically improve their products.
The chemically oriented work will include the synthesis and characterization of precursor polymers and copolymers and their thermal treatment as well as the synthesis and analysis of small model compounds.

PAN Precursor

AnsprechpartnerProf. Dr. Klaus Ruhland, Raum 348 Süd, Telefon: (0821) 598-3361