Topologie korrelierter Systeme

Prof. Christian Pfleiderer

Forschungsgebiet

Scientific activities covered at our institute include the fundamental properties of magnetic and superconducting materials (bulk compounds and thin films), materials science and a few selected problems in particle physics. The institute has a long tradition in neutron related research, notably the development of state-of-the-art neutron scattering techniques. Amongst other contributions we provide the scientific partnership of TUM for the beam lines Reseda, Mira, Antares and Nepomuc at FRM II. In addition we operate a number of laboratories at the Physik-Department that are focussed on studies of bulk properties under extreme conditions, materials preparation and materials characterisation.

Adresse/Kontakt

James-Franck-Str. 1
85748 Garching b. München

Mitarbeiterinnen und Mitarbeiter der Arbeitsgruppe

Professorinnen und Professoren

Mitarbeiterinnen und Mitarbeiter

Lehrangebot der Arbeitsgruppe

Lehrveranstaltungen mit Beteiligung der Arbeitsgruppe

Titel und Modulzuordnung
ArtSWSDozent(en)Termine
Einführung in die Physik der kondensierten Materie
Zuordnung zu Modulen:
VO 4 Pfleiderer, C. Mo, 12:00–14:00, PH HS2
Do, 08:30–10:00, PH HS2
TRR80 Focused Lectures
Zuordnung zu Modulen:
VO 0.5 Böni, P. Pfleiderer, C.
Seminar über experimentelle Methoden der Festkörperphysik
Zuordnung zu Modulen:
PS 2 Hugenschmidt, C. Pfleiderer, C. Do, 10:45–12:15, PH 2224
Übung zu Einführung in die Physik der kondensierten Materie
Zuordnung zu Modulen:
UE 2
Leitung/Koordination: Pfleiderer, C.
Termine in Gruppen
Demonstrationsversuche für die Experimentalphysik
Zuordnung zu Modulen:
PR 1 Pfleiderer, C.
Elektronikpraktikum (Analogteil)
Zuordnung zu Modulen:
PR 4 Böni, P.
Mitwirkende: Spallek, J.

Ausgeschriebene Angebote für Abschlussarbeiten an der Arbeitsgruppe

Extreme Quanten-Materie im Festkörper

The collective excitations of solids at very low excitation energies may be described as particle-like states. Important examples are phonons, magnons or plasmons. However, increasing evidence suggests a dominant role of subtle stochastic processes and that proper account of the full spectrum of fluctuations yields the key for many of the most puzzling materials properties reported in the recent literature. Ultra-high resolution neutron spectroscopy provides deep insights on the nature and the consequences of these subtle fluctuations, in particular the emergence of entangled quantum matter.

The proposed project pursues measurements of stochastic processes of extreme quantum matter in solids with ultra-high energy resolution by means of neutron resonance spin-echo spectroscopy. In recent years we have implemented a new and extremely powerful variant of this technique at FRM II. The experiments range from technical developments of the neutron beam-line RESEDA at FRM II, the experimental studies, analysis of the data and complementary measurements using other neutron scattering techniques as well as laboratory based methods, where suitable.

 
geeignet als
  • Masterarbeit Physik der kondensierten Materie
  • Masterarbeit Applied and Engineering Physics
Themensteller(in): Christian Pfleiderer
Kalorimetrie von Quanten-Phasen-Übergängen im Transversalen Magnetfeld

In materials with strong magnetic anisotropies, long-range magnetic order can be destroyed with a magnetic field applied along the hard magnetisation axis. At ultra-low temperatures in the milli-Kelvin range this suppression entails the perhaps theoretically best understood examples of a quantum phase transition, i.e., a phase transition driven by a change of quantum entanglement. 

Even though the specific heat represents the most important thermodynamic probe of the nature of the excitations of a given material, measurements across transverse field tuned quantum phase transitions, despite many decades of research, have not been reported in the literature, because the presence of strong magnetic torques limit the thermal decoupling from the bath.

The objective of the thesis project are measurements of the specific heat in materials with strong electronic correlations and large magnetic anisotropies under magnetic fields applied along the hard magnetisation axis. An experimental device capable of performing the necessary measurements was recently developed and commissioned by our group. It is world-wide unique, permitting for the first time the required measurements. The experiments comprise of highly sophisticated experimental techniques and the theoretical interpretation based on quantum field theoretical concepts.

 
geeignet als
  • Masterarbeit Physik der kondensierten Materie
  • Masterarbeit Applied and Engineering Physics
Themensteller(in): Christian Pfleiderer
Neutronenstreuung an nicht-zentrosymmetrischen Cer-Verbindungen
geeignet als
  • Masterarbeit Physik der kondensierten Materie
  • Masterarbeit Applied and Engineering Physics
Themensteller(in): Christian Pfleiderer
Quanten-Materialien für Energie-relevante Technologien

In the history of mankind the discovery of materials with hitherto unknown properties has been been recognized by the names attributed to entire epochs. In turn, the preparation of large, high-quality single crystals of novel materials represents a prerequisite for technological progress on some of the most pressing grand challenges. In particular, materials with macroscopic properties arising from the quantum entanglement of the underlying spin and charge degrees of freedom bear great potential in the context of energy-relevant technologies.

The proposed project concerns single crystal growth of selected quantum materials of interest for energy-relevant technologies, and the associated detailed characterisation of the structural and physical properties. For the growth of high purity samples we have developed a world-wide unique preparation chain satisfying ultra-pure conditions. It combines pre-growth casting and post-growth purification furnaces with state-of-the-art optical float-zoning. The experiments lay the foundations for a broad range of studies in collaboration with national and international partners.

 
geeignet als
  • Masterarbeit Physik der kondensierten Materie
  • Masterarbeit Applied and Engineering Physics
Themensteller(in): Christian Pfleiderer
Spektroskopie von elektronischen Instabilitäten durch Quanten-Oszillationen

In a metal the application of large magnetic fields at very low temperatures causes Landau quantisation of the density of states. The associated quantum oscillations in the magnetic field dependence of the free energy, resulting, for instance, in the de Haas-van Alphen or Shubnikov-de Haas effects, provide detailed microscopic information on the electronic structure and low lying electronic excitations of the metallic state. This allows to develop a predictive understanding in the search for novel electronic phases, as well as a search for the break-down of our understanding of the metallic state. 

The proposed project consists in quantum-oscillation spectroscopy of materials near electronic instabilities to unravel the effects of strongly coupled spin, charge and lattice degrees of freedom on the electronic structure of carefully selected materials. Our group operates several state-of-the-art high-field/ultra-low temperature systems for quantum-oscillation spectroscopy of the metallic state. The experiments comprise of highly advanced experimental methods and electronic structure calculations. 

 
geeignet als
  • Masterarbeit Physik der kondensierten Materie
  • Masterarbeit Applied and Engineering Physics
Themensteller(in): Christian Pfleiderer

Abgeschlossene und laufende Abschlussarbeiten an der Arbeitsgruppe

Neutron scattering on geometrically frustrated magnets
Abschlussarbeit im Masterstudiengang Physik (Physik der kondensierten Materie)
Themensteller(in): Christian Pfleiderer
Quantum oscillations in strongly correlated electron systems
Abschlussarbeit im Masterstudiengang Physics (Applied and Engineering Physics)
Themensteller(in): Christian Pfleiderer

Kondensierte Materie

Wenn Atome sich zusammen tun, wird es interessant: Grundlagenforschung an Festkörperelementen, Nanostrukturen und neuen Materialien mit überraschenden Eigenschaften treffen auf innovative Anwendungen.