  Attention is drawn to a possibility to obtain the monochiral helimagnet MnSi
in a magnetic single domain state (SDS) in zero magnetic field limit. It is
shown that this metastable zero field magnetic SDS can be achieved by gradual
decrease of the field down to zero after initial transformation of MnSi to a
spin-polarized state in high fields $H$. This can be achieved only for
$\bf{H}\parallel$ [111]. Investigations of MnSi in magnetic SDS give us a
possibility to determine the two components of low field magnetic
susceptibility of this compound, $\chi_{\perp}(T)$ and $\chi_{\parallel}(T)$
[$\chi_{\perp}$ and $\chi_{\parallel}$ correspond to $\bf{H}\perp$, and
$\bf{H}\parallel$ (111)-plane containing magnetic moments in helically ordered
state]. These results are compared with macroscopic magnetic susceptibility of
MnSi earlier determined for this compound only in magnetic multi domain state
(MDS). In addition our results are compared with the data reported for some
non-monochiral helimagnets. Characteristic features of monochiral helimagnets
are elucidated.
