본 연구에서는 하지층으로 Mo을 사용한 스핀밸브구조에서 반강자성체 IrMn의 두께 변화에 따른 자기적 특성을 연구하였다. 사용된 스핀밸브는 Si기판/$SiO_2/Mo(17;{AA})NiFe(21;{AA})/CoFe(28;{AA})/Cu(22;{AA})/CoFe(18;{AA})/IrMn(t;{AA})/Ta(25;{AA})$ 구조이다. Mo 박막의 비저항은 $600^{circ}C$에서 $650^{circ}C$ 열처리 후 급격히 증가하였다. 반강자성체인 IrMn의 두께 변화(130 ${AA}$까지)에 따른 자기저항비와 교환결합력을 측정하였다. IrMn의 두께가 65 ${AA}$ 일때 자기저항비와 교환결합력은 9.65%와 337.5 Oe로 최고값을 나타냈다. 그러나 두께를 더욱 증가시킨 97.5 ${AA}$ 일때 자기저항비와 교환결합력은 8.2%와 285 Oe로 감소하였으며, IrMn의 두께가 130 ${AA}$ 일때 자기저항비와 교환결합력은 더욱 감소한 7.65%와 257.5 Oe이었다.
In this research, magnetic properties of spin valve structures using IrMn layers as antiferromagnetic were studied depending on the thickness of the pinned layer. The spin valve structure was Si substrate/$SiO_2(2,000;{AA})/Mo(17;{AA})NiFe(21;{AA})/CoFe(28;{AA})/Cu(22;{AA})/CoFe(18;{AA})/IrMn(t;{AA})/Ta(25;{AA})$. Also, Mo film was deposited on Si substrates and the thermal annealing effect was analyzed. The resistivity of the Mo film was increased as an annealing temperature was increased up to $600^{circ}C$. The variations of MR ratio were related with magnetic exchange coupling field of the spin valve structures for various IrMn pinned layer thickness up to 130 ${AA}$. MR ratio and $H_{ex}$ of spin valves was about 9.05% and 277.5 Oe when the thickness of the IrMn pinned layer was $32.5;{AA}(t=32.5;{AA})$. It was increased to 9.65% and 337.5 Oe for $t=65;{AA}$. For $t=97.5;{AA}$, the MR ratio and Hex decreased to 8.2% and 285 Oe, and further decrease was observed up to $t=130;{AA}$.
