Magnetic anisotropy and conical phase transition in monoaxial chiral magnets.

Magnetic anisotropies in chiral spin systems can affect dramatically the allowed stable magnetic configurations. Using a Green's function approach, we examine the role of fluctuations in determining boundaries between allowed states in a monoaxial chiral magnet. The effects of uniaxial anisotropy are found to be most pronounced near the point separating the helicoidal, ferromagnetic, and paramagnetic phases. The cone state, which can appear when an external magnetic field is applied, is particularly strongly affected near the boundary with the paramagnetic phase. A metastable region is found, indicating the appearance of a fluctuation-induced phase transition. This metastable region arises from off-diagonal elements in the Green's functions, and can exist even without anisotropy. [ABSTRACT FROM AUTHOR]