Curie Temperature decreases linearly with pressure and with an inner core pressure of approx. 360 GPa it would be necessary to determine the Tc at that pressure.

The relative motion between the inner core and the liquid outer core would produce either a lead-synchronicity-lag, resulting in a field in one direction-no field-reversed field.

Taking the inner core rotation to be constant, the cause of relative variation in speed of rotation of outer core to inner core could be due to a variable balance of the earths rotation as a result of plate tectonics. This would result a variation of rotation of the outer core....but what force could increase its rotational speed? Could be our movement around the Sun, Moons orbit.....