= Subcritical magnetoconvection
Subcritical magnetoconvection means finite-amplitude <convection> on the stable side of the linear conductive-state threshold. At large <magnetic Reynolds number>, <flux expulsion> can reduce interior magnetic inhibition enough to sustain a nonlinear convective cell even when infinitesimal disturbances decay in the unredistributed imposed field. Stable subcritical states can produce hysteresis and <magnetic flux separation>. A schematic saturated <amplitude equation> $\dot A=\mu A+c|A|^2A-d|A|^4A$, $c,d>0$, has an unstable lower branch and stable upper radial branch for $-c^2/(4d)<\mu<0$, coexisting with stable $A=0$. This illustrates bistability; it is not a derivation of coefficients for all magnetoconvection geometries.
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