Postdoctoral Fellow in Experimental Quantum Materials – Nanocalorimetry of Complex Superconductivity

The Department of Physics is one of the biggest departments within the Faculty of Science and supports a broad range of basic research in experimental and theoretical physics. It has about 250 employees, of which 95 are PhD students. Many have been internationally recruited. The Department is part of the AlbaNova University Center, which apart from the Department of Physics houses the Department of Astronomy, the Physics Departments at the Royal Institute of Technology (KTH), and the Nordic Institute for Theoretical Physics (Nordita).
You can read more about us here: Department of Physics

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Project description

The project is part of a research program aiming to elucidate the properties of a possible new state of matter in the iron-based superconductor (Ba,K)Fe2As2, where experiments indicate a phase with broken time-reversal symmetry above the conventional superconducting transition and where electrons appear to form four-particle correlations (“electron quadrupling condensate”). The experimental objective at Stockholm University is to establish robust thermodynamic and dynamical signatures of these phases and to determine the symmetry of the low-temperature superconducting order through field- and angle-dependent measurements. The work builds on high-resolution membrane-based nanocalorimetry (AC calorimetry) with sample rotation in magnetic fields and is complemented by transport measurements to elucidate vortex correlations and fluctuation regimes, torque magnetometry, and thermal impedance spectroscopy (TISP). The project is carried out in close collaboration with theory and experimental partners within the program.

Main responsibilities

The duties include planning, performing, and analyzing experimental low-temperature measurements in magnetic fields on (Ba,K)Fe2As2 and related reference samples, with a focus on:

• detailed mapping of heat capacity and thermodynamic state functions as a function of temperature, magnetic field, and field orientation, including determination of critical fields and anisotropies
• angle-resolved specific-heat measurements at low temperatures to test gap structure/nodes and discriminate between candidate order parameters
• measurements in the relevant field and temperature range in/around the proposed “quadrupling” phase, including application and further development of TISP for frequency-dependent thermal response and related relaxation effects
• complementary transport/vortex studies (e.g., multi-terminal geometries) to identify vortex-liquid behaviour and fluctuation contributions
• data processing, uncertainty analysis, documentation, and publication in leading journals, as well as presentation of results at international meetings
• contributing to methodological development in the laboratory
• some supervision of student projects may be included

Qualification requirements

Postdoctoral positions are appointed primarily for purposes of research. Applicants are expected to hold a Swedish doctoral degree or an equivalent degree from another country.

Assessment criteria

The degree must have been completed at latest before the employment decision is made, but no more than three years before the closing date. An older degree may be acceptable under special circumstances. Special reasons refer to sick leave, parental leave, elected positions in trade unions, service in the total defense, or other similar circumstances as well as clinical attachment or service/assignments relevant to the subject area.

In the appointment process, special attention will be given to …

About the employment

The position involves full-time scholarship for two years with the possibility of extension
under special circumstances. Start date 2026-02-09 or as per agreement.

Stockholm University strives to be a workplace free from discrimination and with equal
opportunities for all.

We offer

With us, you will experience the dynamic interaction between higher education and research that makes Stockholm University an exciting and creative environment. You will work in an international environment and get favorable conditions. The university is located in the National City Park with good transport links to the city

Stockholm University strives to be a workplace free from discrimination and with equal opportunities for all.

Contact

Further information about the position can be obtained from Andreas Rydh,
phone: +46 8 5537 8692, andreas.rydh@fysik.su.se

Application

You apply directly to Andreas Rydh, andreas.rydh@fysik.su.se. It is the responsibility of the applicant to ensure that the application is complete in accordance with the instructions in the job advertisement, and that it is submitted before the deadline.

Please include the following information with your application

• Your contact details and personal data
• Your highest degree
• Your language skills
• Contact details for 2–3 references
• Cover letter
• CV – degrees and other completed courses, work experience and a list of Publications
• Research proposal (no more than 3 pages) describing:
  • why you are interested in the field/project described in the advertisement
  • why and how you wish to complete the project
  • what makes you suitable for the project in question
  • Copy of PhD diploma
  • Letters of recommendation (no more than 3 files)
  • Publications in support of your application (no more than 3 files).

Welcome to apply!