Magnetic, structural and superconducting phase diagram in bulk Fe-chalcogenides:nematic fluctuations and biquadratic exchange

Datum

02.10.2015

Zeit

14:00 - 15:00

Sprecher

Prof. Dr. Igor Mazin

Zugehörigkeit

Naval Research Laboratory, Center for Computational Material Science, Washington

Sprache

en

Hauptthema

Materialien

Andere Themen

Materialien, Physik

Host

Christine Malbrich

Beschreibung

Abstract Even the bulk FeSe is distinctly unusual, compared to "old" pnictogen-based FeBS, which may be a clue to understanding more exotic FeSe-derivatives. The mystery starts with the FeSe phase diagram: numerous pnictides experience an orthorhombic transition, likely of "spin-nematic" nature, followed by a magnetic transition; external pressure favors superconductivity if the starting phase is magnetic, and suppresses it otherwise, consistent with pressure suppressing spin fluctuations. FeSe, however, experiences an orthorhombic transition with no apparent sign of magnetic ordering, and its Tc raises rapidly with pressure, before switching to the usual, opposite trend. In this talk I will revisit, based on DFT calculations, magnetic interactions in chalcogenides, and show that they, unlike pnictides, demonstrate unusual (and unanticipated) frustration, which supresses magnetic, but not nematic order, and fully explains the nonmonotonic Tc(P) and other aspects of the FeSe phase diagram

Links

• Seminars at the IFW

Letztmalig verändert: 02.10.2015, 09:35:54