Post-doc Opening in Condensed Matter Physics: Novel high-temperature superconductors

Project description

Among many other applications, high-temperature superconducting materials hold great promise for energy saving and storage and for reducing our carbon footprint. However, a major challenge for the actual take-off of an everyday superconducting technology lies in the discovery of appropriate materials, not only with high superconducting transition temperatures (Tc) but also, and very importantly, obtained from abundant and non-toxic raw elements.

In 2006, the discovery of superconductivity in the Fe-based compound LaFePO supplied new exciting opportunities in this field [1]. The initial Tc of 5 K in LaFePO and 8 K in FeSe was soon enhanced by means of chemical substitution (to 26 K in F-doped LaOFeAs, and 55 K in F-doped SmFeAsO) and pressure (37 K in FeSe), and has been reported to reach 100 K in single-layer FeSe on doped SrTiO3. In this outstanding class of unconventional superconductors, however, the Fe atom is invariably associated to pnictogen or chalcogen elements (P, As and Se, S, Te respectively). This circumstance raises the important fundamental question about the link between Fe-based superconductivity and the apparent need of these elements. At the same time, to escape from harmful and comparatively scarce elements such as As and Se is highly desirable so that actual applications of Fe-based superconducting materials can be promoted.

Recently, we have discovered superconductivity in the novel silicide LaFeSiH with superconducting onset at 11 K [2]. This unprecedented material is the first silicide in the family of Fe-based superconductors that surpasses traditional pnictide and chalcogenide compounds. Thus, it represents a major breakthrough in the field and the basis of the ANR project IROMAN that will fund this postdoc position. IRONMAN is an ambitious multi-partner project between the CNRS labs Institut NEEL (Grenoble), ICMCB (Bordeaux) and CRISMAT (Caen). The candidate will play a central role in the project, as he/she will determine experimentally at Institut NEEL the interesting physical properties of the novel LaFeSiH-like materials that will be synthetized for the first time in the framework of this project. This will define a radically new playground to understand the rich physics of the Fe-based superconductors and promote future applications.

[1] See H. Alloul and A. Cano, Special issue on Iron-based superconductors, C. R. Phys. 17, 1 (2016), and the references therein for recent reviews.

[2] F. Bernardini, G. Garbarino, A. Sulpice, M. Núñez-Regueiro, E. Gaudin, B. Chevalier, M.-A. Méasson, A. Cano, and S. Tencé, Iron-based superconductivity extended to the novel silicide LaFeSiH, PRB 97, 100504(R) (2018).

Position details

The project will take place at the Institut NEEL in Grenoble, an internationally recognized laboratory for its expertise in condensed matter physics and materials science. The candidate will be in close contact with researchers that are experts in the field. This study is part of the ANR project IRONMAN (Novel As/Se-free Iron-based Superconductors) and will be carried out in close collaboration with crystallographers CRISMAT (Caen), the chemists of the Institute of Chemistry of Condensed Matter of Bordeaux (ICMCB) and the theory group at Institute NEEL.

The candidate

We are looking for a passionate of superconductivity willing to undertake the challenge of the experimental investigation of a completely new family of high-temperature unconventional superconductors. The successful candidate is expected to have a strong background in condensed matter physics and materials science, and ideally some experience in high-temperature superconductivity. He/she should master, in particular, electrical resistivity and magnetization measurements with experience on contact assembly on submillimeter samples, either manually or by nanofabrication methods. Additional experience in X-ray and/or neutron diffraction will be helpful for the project, and familiarity with high-pressure measurement techniques and/or Raman spectroscopy will be a plus. Beyond that, the candidate is expected to be autonomous, able to take initiative, and ease with scientific writing.