Polar Order and Frustrated Antiferromagnetism in Perovskite Pb2MnWO6 Single Crystals

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• 作者：Sergey A. Ivanov ; Alexander A. Bush ; Adam I. Stash ; Konstantin E. Kamentsev ; Valerii Ya. Shkuratov ; Yaroslav O. Kvashnin ; Carmine Autieri ; Igor Di Marco ; Biplab Sanyal ; Olle Eriksson ; Per Nordblad ; Roland Mathieu
• 刊名：Inorganic Chemistry
• 出版年：2016
• 出版时间：March 21, 2016
• 年：2016
• 卷：55
• 期：6
• 页码：2791-2805
• 全文大小：740K
• ISSN：1520-510X

文摘

Single crystals of the multiferroic double-perovskite Pb₂MnWO₆ have been synthesized and their structural, thermal, magnetic and dielectric properties studied in detail. Pure perovskite-phase formation and stoichiometric chemical composition of the as-grown crystals are confirmed by X-ray single-crystal and powder diffraction techniques as well as energy-dispersive X-ray and inductively coupled plasma mass spectrometry. Detailed structural analyses reveal that the crystals experience a structural phase transition from the cubic space group (s.g.) Fm3̅m to an orthorhombic structure in s.g. Pn2₁a at about 460 K. Dielectric data suggest that a ferrielectric phase transition takes place at that same temperature, in contrast to earlier results on polycrystalline samples, which reported a transition to s.g. Pnma and an antiferroelectric low-temperature phase. Magnetic susceptibility measurements indicate that a frustrated antiferromagnetic phase emerges below 8 K. Density functional theory based calculations confirm that the cationic order between Mn and W is favorable. The lowest total energy was found for an antiferromagnetically ordered state. However, analyses of the calculated exchange parameters revealed strongly competing antiferromagnetic interactions. The large distance between the magnetic atoms, together with magnetic frustration, is shown to be the main reason for the low value of the ordering temperature observed experimentally. We discuss the structure–property relationships in Pb₂MnWO₆ and compare these observations to reported results on related Pb₂BWO₆ perovskites with different B cations.