Extreme Conditions Physics

In condensed matter physics, experiments at low temperature, high pressure and high magnetic field are widely used to elucidate the physical properties of a material. In this module, starting with He and going to modern unconventional superconductors, we will investigate the phase diagrams of various correlated materials. We will dig into the physics of the appearing groundstates which are induced by changes of temperature, pressure or field, with the aim to draw analogies between different systems. A part of the module will also deal with the technical aspects of how extreme conditions are produced in the laboratory. 

1) Low temperature

• Properties of quantum liquids
• Fermi liquid
• Superfluidity in 3He and 4He
• Two-fluid model
• Bose Einstein condensation
• Phase transitions
• Unconventional superconductivity
• Low temperature techniques

2) High pressure

• Pressure-induced phase transitions
• Quantum phase transitions
• Phase diagrams of correlated electron systems
• High pressure techniques

3) High magnetic field

• High field techniques
• Quantum oscillations
• Field induced phase transitions

After the successful participation at the module, the participants are able to:

• draw correct phase diagrams of He and correlated electron systems
• describe apparent phases and their remarkable physical properties
• name and explain examples of current topics in condensed matter physics that are studied using extreme conditions
• connect physical properties of a material to the relevant magnetic or electronic interactions
• draw analogies between superfluidity and superconductivity
• chose the appropriate techniques to conduct experiments in different extreme conditions having in mind limits, advantages and disadvantages of the technique

Introduction to solid state physics (PH1001 or PH1302), basic knowledge of superconductivity

This module consists of a lecture and exercise classes. A variety of teaching methods are used to reach the learning outcomes which are presented in every lecture. The thematically structured contents given above are presented on the blackboard with the use of powerpoint to show graphics and experimental results. Physical concepts are explained. Instructional videos are shown where appropriate. Illustrative material is also shown such as pressure cells or parts of magnets. An active participation and direct learning of the students is fostered by questions to the audience, animated discussions and work in small groups. Student questions are welcome at any time and used for further deepening of the understanding. Each student will give a small presentation in the last part of the lecture and therefore extend their knowledge on an example material of current research interest that is studied in extreme experimental conditions.

Sheets with exercises are published on the moodle every week. The students should solve these exercises at home and hence apply the learned physical concepts to specific example problems. Exercises can be small calculations but also questions about a scientific article or book chapter. Open questions from the exercises but also from the lecture are discussed during the exercise classes where students also present the solutions of the weekly exercise sheets. Exercise sheets from every student can be handed in and are corrected.

The blackboard is used and students take notes. Powerpoint is mainly used to show graphics, videos, photographs or experimental results. The slides are made available to the students in a moodle associated to the course.

The students will also find additional literature there.

Excercise sheets are propsed and corrected every week.

• C. Enss and S. Hunklinger: Low Temperature Physics, Springer, (2010)
• F. Pobell: Matter and Methods at Low Temperature, Springer, (2007)
• J.F. Annett: Superconductivity, Superfluids and Condensates, Oxford University Press, (2005)
• J. Loveday: High-Pressure Physics, Chapman and Hall/CRC, (2012)

There will be an oral exam of 25 minutes duration. Therein the achievement of the competencies given in section learning outcome is tested exemplarily at least to the given cognition level using comprehension questions and sample calculations.

For example an assignment in the exam might be:

• Drawing of phase diagram of a correlated electron system and explanation of the appearing phases.
• Explanation of physical properties of unconventional superconductors and list of Erläuterung examples.
• Reasoned choice of the adapted experimental techniques for a given experiment in extreme conditions.

Participation in the exercise classes is strongly recommended since the exercises prepare for the problems of the exam and rehearse the specific competencies.

There will be a bonus (one intermediate stepping of "0,3" to the better grade) on passed module exams (4,3 is not upgraded to 4,0). The bonus is applicable to the exam period directly following the lecture period (not to the exam repetition) and subject to the condition that the student passes the mid-term of active participation in the tutorial with regular presentation of results.