We investigate the spin structure of a uni-axial chiral magnet near the<br />
transition temperatures in low fields perpendicular to the helical axis. We<br />
find a fan-type modulation structure where the clockwise and counterclockwise<br />
windings appear alternatively along the propagation direction of the modulation<br />
structure. This structure is often realized in a Yoshimori-type (non-chiral)<br />
helimagnet but it is rarely realized in a chiral helimagnet. To discuss<br />
underlying physics of this structure, we reconsider the phase diagram (phase<br />
boundary and crossover lines) through the free energy and asymptotic behaviors<br />
of isolated solitons. The fan structure appears slightly below the phase<br />
boundary of the continuous transition of instability-type. In this region,<br />
there are no solutions containing any types of isolated solitons to the mean<br />
field equations.