[institut] Center for Solid State Physics and New Materials Seminar - Wednesday, June 1st 2016 at 13:00 h

[Nenad Lazarevic]

Поштоване колегинице и колеге,

Са задовољством вас позивам на семинар Центра за физику чврстог стања и 
нове материјале под насловом

„Low-lying excitations in the orbitally active A-site spinels FeSc2S4, 
FeCr2O4 and FeCr2S4”

који ће одржати др Јоаким Дајсенхофер из Центра за електронске 
корелације и магнетизам Института за физику, Универзитета у Аугсбургу. 
Семинар ће се одржати у читаоници Института за физику „Др Драган 
Поповић“, у среду 1. jуна 2016. године са почетком у 13 часова.

Срдачан поздрав,
Ненад Лазаревић


Dear Colleagues,

It is my pleasure to invite you to the Center for Solid State Physics 
and New Materials Seminar entitled

„Low-lying excitations in the orbitally active A-site spinels FeSc2S4 , 
FeCr2O4 and FeCr2S4”

which will be given by Dr. Joachim Deisenhofer from Center for 
Electronic Correlations and Magnetism, Experimental Physics V, 
University of Augsburg, Germany. The seminar will be held on Wednesday, 
June 1st 2016 at 13:00 in “Dr. Dragan Popović” library reading room of 
the Institute of Physics Belgrade.

Abstract of the talk:

The spinel systems FeSc2S4, FeCr2O4, and FeCr2S4 show cubic symmetry at 
room temperature, but they reveal very different magnetic ground states 
at low temperatures. FeSc2S4 does not reveal any structural transition 
below room temperature, but forms a spin-orbital liquid state at lowest 
temperatures, where the orbital and spin degrees of freedom of the Fe 
ions do not show long-range order but are entangled over several Fe 
sites [1]. In FeCr2S4 a long-range ferromagnetic order below about 170 K 
is followed by an incommensurate magnetic structure below about 50 K. 
Finally, a multiferroic state with orbital order is reached below 10 K 
[2]. Similar magnetic structures occur in FeCr2O4, but a tetragonal 
distortion at 135 K precedes magnetic ordering and indicates a stronger 
Jahn-Teller coupling than in FeCr2S4. These different states are tracked 
and discussed via optical excitations of the low-lying electronic states 
of the Fe2+ ions using THz- and FIR-spectroscopy.

[1] N. J. Laurita, J. Deisenhofer, LiDong Pan, C. M. Morris, M. 
Schmidt, M. Johnsson, V. Tsurkan, A. Loidl, N. P. Armitage. PRL 114, 
207201 (2015).
[2] J. Bertinshaw, C. Ulrich, A. Günther, F. Schrettle, M. Wohlauer, S. 
Krohns, M. Reehuis, A.J. Studer, M. Avdeev, D. V. Quach, J. R. Groza, V. 
Tsurkan, A. Loidl, and J. Deisenhofer, Scientific Reports 4, 6079 
(2014).


Best regards,
Nenad Lazarevic

-- 
Institute of Physics Belgrade
Pregrevica 118, 11080 Belgrade, Serbia
http://www.ipb.ac.rs/