Materials with a 5d 4 electronic configuration are generally considered to have a nonmagnetic ground state (J = 0). Interestingly, Sr2YIrO6 (Ir 5+ having 5d 4 electronic configuration) was recently reported to exhibit long-range magnetic order at low temperature and the distorted IrO6 octahedra were discussed to cause the magnetism in this material. Hence, a comparison of structurally distorted Sr2YIrO6 with cubic Ba2YIrO6 may shed light on the source of magnetism in such Ir 5+ materials with 5d 4 configuration. Besides, Ir 5+ materials having 5d 4 are also interesting in the context of recently predicted excitonic types of magnetism. Here we report a single-crystal-based analysis of the structural, magnetic, and thermodynamic properties of Ba2YIrO6. We observe that in Ba2YIrO6 for temperatures down to 0.4 K, long-range magnetic order is absent but at the same time correlated magnetic moments are present. We show that these moments are absent in fully relativistic ab initio band-structure calculations; hence, their origin is presently unclear.

Single crystals of the charge-transfer salt picene/2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane have been grown using physical vapor transport. The crystal structure was determined using single-crystal X-ray diffraction. It was found that the crystals grow in a 1:1 molecular ratio and adopt a monoclinic structure with alternate stacking. Both Xray data and Raman measurements show that the grown crystals are of good quality. From structure and infrared data, the charge transfer between acceptor and donor molecules was estimated to be approximately 0.14−0.19 electron. Transport measurements indicate a nonmetallic ground state with an activation energy of 0.6 eV. The supporting density functional theory calculations on molecular model systems as well as on crystalline structures confirm the amount of charge transfer and provide first insights into the electronic structure of the new material.

A method is described for measuring the pyroelectric coefficient, dc dielectric constant, and volume resistivity of a polar material over a broad temperature range. The technique is based on the observation of the capacitive charging of a pyroelectric sample by the pyroelectric current generated during a continuous temperature change. This method has the advantages of requiring neither a heat flux measurement nor the attaining of isothermal conditions and does not alter the domain structure of a ferroelectric material. Values of the above properties were measured for Clevite PZT-5 (lead-zirconate-titanate ceramic) over the temperature range from −200 to 200°C. The pyroelectric coefficient of Clevite PZT-4 (lead-zirconate-titanate ceramic) was measured by a simplified method over the temperature range of 25 to 75°C.

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