The discovery of Fe based superconductors in 2008 showed that the unconventional (high-temperature) superconductivity in cuprates is not unique but can occur in other material classes, too.  The highest TC of this class of novel superconductors to date is 56.3K and was already found in 2008 for (Gd0.8Th0.2)FeAsO, a member of the so-called 1111-family.

Subsequently the 122-family was discovered with a maximal TC of 38K for Ba0.6K0.4Fe2As2 and was followed by the 111-class (e.g. LiFeAs with TC=18K) and the 11-system FeSe with TC=8K. In our current research efforts we focus on single-crystal growth of the latter class of FeSe superconductors and Electron Spin Resonance spectroscopy of this new class of materials.



Improvement of the superconducting properties of FeSe0.5Te0.5 by Mn substitution

A. Günther, J. Deisenhofer, Ch. Kant, H.-A. Krug von Nidda, V. Tsurkan, and A. Loidl
Supercond. Sci. Technol. 24, 045009/1-9 (2011).

Physical properties of FeSe0.5Te0.5 single crystals grown under different conditions

V. Tsurkan, J. Deisenhofer, A. Günther, Ch. Kant, M. Klemm, H.-A. Krug von Nidda, F. Schrettle, and A. Loidl
Eur. Phys. J. B 79, 289-299 (2011).

Magnetic fluctuations and superconductivity in iron pnictides as probed by electron spin resonance

N. Pascher, J. Deisenhofer, H.-A. Krug von Nidda, M. Hemmida, H. S. Jeevan, P. Gegenwart, and A. Loidl
Physical Review B 82, 054525 (2010).
This paper was selected for the Virtual Journal of Applications of Superconductivity .

Magnetic and superconducting transitions in Ba1-xKxFe2As2 studied by specific heat

Ch. Kant, J. Deisenhofer, A. Günther, F. Schrettle, A. Loidl, M. Rotter, and D. Johrendt
Physical Review B 81, 014529 (2010).
This paper was selected for the Virtual Journal of Applications of Superconductivity .

Strong reduction of the Korringa relaxation in the spin-density wave regime of EuFe2As2 observed by electron spin resonance

E. Dengler, J. Deisenhofer, H.-A. Krug von Nidda, Seunghyun Khim, J.S. Kim, Kee Hoon Kim, F. Casper, C. Felser, and A. Loidl,
Physical Review B 81, 024406 (2010).

Competition of magnetism and superconductivity in Ba1-xKxFe2As2

Marianne Rotter, Marcus Tegel, Inga Schellenberg , Falko M. Schappacher, Rainer Pöttgen, Joachim Deisenhofer, Axel Günther, Florian Schrettle, Alois Loidl, and Dirk Johrendt
New Journal of Physics 11, 025014 (2009).