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Cascading transitions toward unconventional charge density wave states in the quasi-two-dimensional monophosphate tungsten bronze P 4 W 16 O 56

2020; International Union of Crystallography; Volume: 7; Issue: 2 Linguagem: Inglês

10.1107/s2052252519016695

2052-2525

Elen Duverger-Nédellec, Alain Pautrat, Kamil K. Kolincio, L. Hervé, Olivier Pérez,

Transition Metal Oxide Nanomaterials

Single crystals of the m = 8 member of the low-dimensional monophosphate tungsten bronzes (PO 2 ) 4 (WO 3 ) 2 m family were grown by chemical vapour transport technique and the high crystalline quality obtained allowed a reinvestigation of the physical and structural properties. Resistivity measurements revealed three anomalies at T C1 = 258 K, T C2 = 245 K and T C3 = 140 K, never observed until now. Parallel X-ray diffraction investigations showed a specific signature associated with three structural transitions, i.e. the appearance of different sets of satellite reflections below T C1 , T C2 and T C3 . Several harmonics of intense satellite reflections were observed, reflecting the non-sinusoidal nature of the structural modulations and a strong electron–phonon coupling in the material. These transitions could be associated with the formation of three successive unconventional charge density wave states.