Ultrasonic properties near 50 K of the quasi-one-dimensional conductors A0. 30MoO3 (A= K, Rb) and Rb0. 30 (Mo1− xVx) O3

Michel Saint-Paul (1) , Jean Dumas (1) , Jacques Marcus (2)

1 NEEL - MagSup - Magnétisme et Supraconductivité
2 NEEL - AUTOCARAC - Automatisation & caractérisation

The charge density wave (CDW) nonlinear conductivity of the blue bronzes A0.30MoO3 (A = K, Rb) shows two different regimes depending on the temperature: a strongly damped CDW motion above ~50 K and a CDW motion with almost no damping below ~50 K. In a search for an elastic signature of this CDW behaviour, we performed ultrasonic measurements on A0.30MoO3 single crystals in the temperature range 4-300 K. In Rb0.30MoO3, at T~50 K, upon cooling, a large increase of the sound velocity for the longitudinal mode measured along the [\bar {2}01] , [102] and b directions is observed. The ultrasonic attenuation coefficient shows an increase down to 50 K followed by a plateau. Similar results are found in K0.30MoO3. In V-doped samples, Rb0.30(Mo1−xVx)O3 (x = 0.4%) the anomaly broadens and is shifted towards higher temperatures. The results are discussed in relation to the changes in the CDW rigidity, disorder and dielectric response. A scenario based on a glass transition for the CDW superstructure is proposed.

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Michel Saint-Paul, Jean Dumas, Jacques Marcus. Ultrasonic properties near 50 K of the quasi-one-dimensional conductors A0. 30MoO3 (A= K, Rb) and Rb0. 30 (Mo1− xVx) O3. Journal of Physics: Condensed Matter, 2009, 21 (21), pp.215603. ⟨10.1088/0953-8984/21/21/215603⟩. ⟨hal-00990181⟩