A current carrying circular coil, suspended freely in a uniform external magnetic field orients to a position of stable equilibrium. In this state :

At equilibrium, net torque on the loop is zero as the net force is already zero on a loop in a uniform magnetic field.

$\overrightarrow{\tau }=\overrightarrow{\mathrm{M}}\times \overrightarrow{\mathrm{B}}=\overrightarrow{0}$

$\mathrm{\theta }=0^0$ (stable equilibrium)

So, the field will be along the axis of the loop.

Hence, field will be perpendicular to the plane of the loop.

In this state, the flux through the coil will be maximum.