with the previous heat treatment plus 19 hours of continuous annealing at 260 u00b0 c the curve has become more convex but the ordering temperature t cr has not changed much remaining around 180 u00b0 c the plot in fig5 shows h ua t for a thermal annealing treatment of 3 cycles at 240 u00b0 c plus 41 hours of continuous annealing at 260 u00b0 c here the room temperature value of h ua has increased to about 40 oe and the shape of h ua t has changed once more so that it is convex at lower temperatures below about 150 u00b0 c and becomes almost linear again at higher temperatures the ordering temperature has increased drastically to about 300 u00b0 c since h ua has now shifted to a temperature exceeding 240 u00b0 c the neel temperature of femn it must be concluded that now the nife is exchange coupled to a different antiferromagnet characterized by a stronger antiferromagnetic order in addition the reappearance of linear behavior in h ua t suggests that the conversion of femn antiferromagnetism at the interface into this new antiferromagnetic system may be very non uniform forming a series of intermediate alloys along the exchange path at the interface the plot in fig6 shows h ua t for a.