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Published on: December 4, 2014
Crystal structure and absence of magnetic order in single-crystalline RuO2
Abstract:
RuO2was considered for a long time to be a paramagnetic metal with an ideal rutile-type structure down to low temperatures, but recent studies on single-crystals claimed evidence for antiferromagnetic order and some symmetry breaking in the crystal structure. We have grown single-crystals of RuO2by vapor transport using either O2or TeCl4as transport medium. These crystals exhibit metallic behavior following aT2low-temperature relation and a small paramagnetic susceptibility that can be attributed to Pauli paramagnetism. Neither the conductance nor the susceptibility measurements yield any evidence for a magnetic or a structural transition between 300 K and ∼4 K. Comprehensive single-crystal diffraction studies with neutron and x-ray radiation reveal the rutile structure to persist until 2 K in our crystals, and show nearly perfect stoichiometry. Previous observations of symmetry forbidden reflections can be attributed to multiple diffraction. Polarized single-crystal neutron diffraction experiments at 1.6 K exclude the proposed antiferromagnetic structures with ordered moments larger than 0.01 Bohr magnetons.
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