If the material is a one-dimensional superconductor where current can only flow with zero resistance along one direction, aligning that direction with the magne

If the material is a one-dimensional superconductor where current can only flow with zero resistance along one direction, aligning that direction with the magnetic field lines should produce the weakest diagmanetism, because the magnetic force is proportional to the cross product of current and magnetic field. If the two are parallel, the force is zero. Of course this could explain why the sample doesn't lift off: it starts out with the superconducting direction at an angle to the magnetic field and relatively strong diamagnetism leading to a righting force until the two directions are nearly aligned and the diamagnetism is too weak to overcome gravity.