STM image of TaS2 surface

TaS2 (and TaSe2) exhibit an electronic phase transition from a normal into a condensed state which is called the Charge Density Wave (CDW) state. The transition is caused by an electron-phonon coupling. STM images of TaS2 show a triangular atomic lattice (a0=0.33 nm) with a superimposed CDW lattice of about 3.5 a0. The CDW lattice is rotated 11° with respect to the atomic lattice.


11 x 11 nm<sup>2</sup> image; z-range 0.8nm
11 x 11 nm2 image; z-range 0.8 nm

To observe the CDW we typically use parameters of 2-3 nA tunneling current and 10-20 mV gap voltage. The atomic lattice can be seen simultaneously when the current is increased to higher values (30 - 40 nA).

6 x 6 nm<sup>2</sup> image; z-range 0.8 nm
6 x 6 nm2 image; z-range 0.8 nm
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