Regensburg 2019 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 53: Frustrated Magnets - Strong Spin-Orbit Coupling (joint session TT/MA)

TT 53.7: Vortrag

Donnerstag, 4. April 2019, 11:00–11:15, Theater

Syntheses and magnetic properties of two sodium ruthenates: Na₃RuO₄ and Na₂RuO₃ — •Vera P. Bader, Alexander Tsirlin, Anton Jesche, and Philipp Gegenwart — EP VI, Center for Electronic Correlations and Magnetism, University of Augsburg, 86135 Augsburg, Germany

Ruthenates show a diversity of magnetic phenomena, e.g. due to strong Ru-O covalency in the case of Ru⁵⁺ [1] and due to the non-magnetic J = 0 state potentially leading to Van Vleck excitons in Ru⁴⁺ [2]. Additionally, geometrical frustration may affect the magnetic properties. We focus on two ruthenates with the Ru-ions in the oxidation state 5+ and 4+, respectively. In Na₃RuO₄ the Ru⁵⁺O₆ octahedra condense into tetramers which are composed of two equilateral triangles. In Na₂RuO₃ the Ru⁴⁺ ions form honeycomb layers. We prepare powder samples of Na₃RuO₄ via solid state reaction in a controlled atmosphere. The measurement of the magnetic susceptibility shows an antiferromagnetic transition at 30 K and suggests suppression of the magnetic order. Specific heat measurements reveal two consecutive phase transitions at 25 K and 28 K. Na₂RuO₃ powder is synthesized by thermal decomposition of a precursor in argon. Due to the layered structure the compound is prone to stacking faults. To improve the quality of the sample different synthesis routes have been compared.
A. Hariki et al., PRB 96, 155135 (2017)
G. Khaliullin, PRL 111, 197201 (2013)