STRONG TEMPERATURE-DEPENDENCE OF THE INTERLAYER EXCHANGE COUPLING STRENGTH IN CO CU/CO SANDWICHES/

We present a study of the temperature dependence of the interlayer cou pling strength in Co(hcp)/Cu sandwiches. The thermal variation of the coupling has been studied between 39 and 300 K by superconducting quan tum interference device magnetometry for the samples corresponding to the first and second maxima in the oscillation of the exchange couplin g of a series of Co/Cu(t(Cu))/Co trilayers. We find a very strong decr ease of the exchange coupling strength between 20 and 300 K. We show t hat the existing theoretical models cannot explain this unusual strong decrease, However, we believe that this behavior could be due to the confinement of carriers of one spin orientation in the spacer layer.