Quasi-two-dimensional electronic properties of the sodium molybdenum bronze, Na0.9Mo6O17

CHARGE DENSITY WAVE INSTABILITY IN TlMo6O17

“…[10][11][12] An anomaly is clearly seen at approximately 24 K, 80 K and 120 K for the lithium, sodium and potassium purple bronzes in their temperature-dependent resistance. 1,13,14 And a different temperature dependence of thermoelectric power behavior is also recently observed in sodium purple bronze, compared to K/Tl purple bronzes. 13 Furthermore, while the resisivities of sodium and potassium purple bronzes show a maximum at low temperature, the lithium bronzes show a sharp increase at about 24 K and a transition to a superconducting state at T c ∼ 2 K. 15 All these suggest that the metal ions play an important role in these q-2D bronzes.…”

“…1,13,14 And a different temperature dependence of thermoelectric power behavior is also recently observed in sodium purple bronze, compared to K/Tl purple bronzes. 13 Furthermore, while the resisivities of sodium and potassium purple bronzes show a maximum at low temperature, the lithium bronzes show a sharp increase at about 24 K and a transition to a superconducting state at T c ∼ 2 K. 15 All these suggest that the metal ions play an important role in these q-2D bronzes. Therefore, although many research works on potassium purple bronzes have been reported, it is worthwhile to study the properties of the thallium molybdenum bronze.…”

“…However, as reported previously, the phase temperatures connected with CDW instabilities in 2D purple bronzes vary over a wide range. They are approximately at 80 K, 110 K and 120 K for sodium, thallium and potassium purple bronzes,1,13,14 respectively. This suggests that the electronic properties of the purple bronzes are somewhat affected by the nature of the alkali metal ion, probably by subtle structural variations of the respective compounds.…”

Observation of Hidden Fermi Surface Nesting in a Two Dimensional Conductor

“…While this model is quite satisfactory for quasi-1D conductors, its application to quasi-2D conductors is problematic, since the 2D susceptibility anomaly is much smaller. However, CDW-PLD instabilities have been observed in quasi-2D conductors, for example, in the purple molybdenum bronzes such as KMo 6 O 17 and Na 0.9 Mo 6 O 17 [4], in monophosphate tungsten bronzes [4] of the form (PO 2 ) 4 (WO 3 ) 2m , and in organic conducting salts such as (BEDT-TTF) 2 ReO 4 (where BEDT-TTF refers to bisethylenedithiotetrafulvalene). Whangbo et al introduced the idea that the Fermi surfaces in these materials can be viewed as a combination of quasi-1D structures, with distinct 1D nesting vectors [1,2].…”

“…The system studied was Na 0.9 Mo 6 O 17 , which possesses a layered structure consisting of planes of Mo-O polyhedra separated by Na ions [5]. Na 0.9 Mo 6 O 17 exhibits quasi-2D transport properties within the (001) cleavage plane, and undergoes a metal-metal transition to a CDW state at 80 K [6]. (While Peierls transitions in 1D systems result in transitions to insulating CDW states, the CDW state in quasi-2D materials remains metallic, as the opening of a band gap occurs only over part of the Fermi surface.)…”