Dresden 2017 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 19: Poster Session: Correlated Electrons 1

TT 19.22: Poster

Montag, 20. März 2017, 15:00–19:00, P2-EG

Magnetic order and spin dynamics in La₂O₂Fe₂O(S/Se)₂ probed by ⁵⁷Fe Mössbauer and ¹³⁹La NMR spectroscopy — •Sirko Kamusella¹, Rajib Sarkar¹, Felix Brückner¹, Vadim Grinenko¹, Hans-Henning Klauss¹, and Byron Freelon² — ¹Institute for Solid State Physics, TU Dresden, D-01069, Germany — ²Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA

We present ⁵⁷Fe Mössbauer and ¹³⁹La NMR studies on La₂O₂Fe₂OS₂ in the magnetically ordered state and paramagnetic state. Similar to La₂O₂Fe₂OSe₂ [1] we observed a non collinear magnetic structure in La₂O₂Fe₂OS₂, accounting for the explicitly broken x-y-symmetry in the layered structure. The magnetism in this compound is based on frustrated J1-J1’-J2 interactions and single-ion anisotropy. However, unexpected observations occurred: The continuous reduction of the principal component V_zz of the EFG below 1.4T_N for both compounds and the continuous slowing down of the spin fluctuations as reflected in the NMR spin lattice relaxation rate (¹³⁹T₁) could be discussed in the context of spin-nematicity.

Therefore, parts of our investigations can be related to advanced theoretical concepts which are used to model the physics in these materials, such as orbital selective Mottness [2], biquadratic spin interactions and two magnon relaxation.