Dresden 2014 – scientific programme

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MA: Fachverband Magnetismus

MA 15: Spin structures and Magnetic Phase Transitions

MA 15.5: Talk

Tuesday, April 1, 2014, 10:30–10:45, HSZ 403

Spin structures and electron lattice coupling in the double perovskite Sr₂FeOsO₆ — Avijit Kumar Paul¹, •Peter Adler¹, Manfred Reehuis², Vadim Ksenofontov³, Binghai Yan¹, Martin Jansen¹, and Claudia Felser¹ — ¹Max-Planck-Institut für Chemische Physik fester Stoffe, Dresden, Germany — ²Helmholtz-Zentrum für Materialien und Energie, Berlin, Germany — ³Johannes Gutenberg-Universität, Mainz, Germany

Double perovskites with an ordered arrangement of transition metal 3d and 4d or 5d sites show remarkable magnetic properties like half-metallic ferromagnetism below 400 K in Sr₂FeMoO₆ or ferrimagnetism with a high T_C of 725 K in the insulator Sr₂CrOsO₆. We have studied the magnetic and electronic properties of insulating Sr₂FeOsO₆ by neutron powder diffraction, ⁵⁷Fe Mössbauer spectroscopy and spin-polarized density functional theory calculations. Sr₂FeOsO₆ shows two magnetic phase transitions below 140 and 67 K, respectively. Similar as in related systems the spin structures reveal ferrimagnetic ordering of Fe and Os moments within the planes of the tetragonal crystal structure. Along c, however, two different spin alignment patterns are adopted which lead to overall antiferromagnetic behavior. Our experimental and theoretical results suggest a frustrated magnetic behavior, where the frustration is partially released by a Peierls-like lattice modulation and a switch of the spin structure below 67 K. Thus, Sr₂FeOsO₆ features an intimate interplay of lattice, spin and orbital degrees of freedom.