Pd(III) Mott–Hubbard Compounds - Material Designs and New Physical Properties in MX-and MMX-Chain Compounds - page 49

Fig. 4.16 STM images of [Ni 1 x Pd x (chxn) 2 Br]Br 2 with x ¼ (a) 0.70, (b) 0.80, (c) 0.86, and

200 ˚ 2 ). The sample bias was +1.0 V. The directions of the 1D
chains are shown as white arrows , and the blue arrow shows the 1D chain on which a spin soliton
was observed

(d) 0.95 in the bc plane (200

These CDW states were coherent over approximately ten metal sites along the b
axis, but almost no coherence was observed along the c axis. In the image of the
x ¼

0.86 complex, coherence was clearly more propagated than that of the

x ¼ 0.86 complex spread over

approximately 20 metal sites along the b axis, and two or three metal sites along
the c axis. The image of the x ¼

0.80 complex. The CDW coherence of the x ¼

0.95 complex showed extensive twofold periodic-
ity. Along the b axis, for the chains in a CDW state, the twofold periodicity
extended over the measured length (ca. 40 metal sites), which shows that the
CDW coherence along the chain is longer than 20 nm. Along the c axis, on the
other hand, the CDW coherence is spread over approximately six or seven sites. We
plotted the CDW coherence length as a function of x in Fig. 4.17 together with the
data obtained by using X-ray diffuse scattering measurements made by
Wakabayashi et al. [ 9 ]. The CDW coherence determined by using STM is in
agreement with the X-ray diffuse scattering results. The CDW coherence
propagated with an increase in the value of x .