Cascading transitions toward unconventional charge density wave states in the quasi-two-dimensional monophosphate tungsten bronze P4W16O56

Elen Duverger-Nédellec (1) , Alain Pautrat (1) , Kamil K Kolincio (2) , Laurence Hervé (1) , Olivier Pérez (1)

1 CRISMAT - Laboratoire de cristallographie et sciences des matériaux
2 GUT - Gdańsk University of Technology

Single crystals of the m = 8 member of the low-dimensional monophosphate tungsten bronzes (PO 2) 4 (WO 3) 2m 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 nonsinusoidal 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.

Mots clés: Phase transitions; Charge density waves; Modulated structures; Inorganic materials; Aperiodic structures; X-ray diffraction; Resistivity

Domaines: Physique [physics]

Elen Duverger-Nédellec, Alain Pautrat, Kamil K Kolincio, Laurence Hervé, Olivier Pérez. Cascading transitions toward unconventional charge density wave states in the quasi-two-dimensional monophosphate tungsten bronze P4W16O56. International Union of Crystallography journal, 2020, 7, pp.184 - 192. ⟨10.1107/s2052252519016695⟩. ⟨hal-03094806⟩