DEVELOPMENT OF A NEW ELECTROMECHANICAL TRANSDUCER USING SPIN VALVE ELEMENTS

针对自旋阀元件在新型机电换能器中的应用，进行了基础研究，得到了以下结果。1.大型交换相互作用场。i<ex>）在Cu/FeCo/MnPt薄膜中，<ex>退火后Mn含量为51at%的MnPt薄膜的H_2最大。（<51><49>2）FeCo/MnPt双层膜退火时，CuAu-Ⅰ型fct有序MnPt晶体生长，在230 ℃以上引起H_2增加<ex>，在320 ℃时达到最大值286 - 356 Oe，在350 ℃以上，由于<ex>层间扩散，H_2值降低，RBS证实了这一点。这带来了热稳定性的改善。（1）FeCo（50*）/Cu（t_1）<Cu>/FeCo（35*）/MnPt（300*）薄膜的热稳定性：<Cu>在290 ℃退火后，t_1 = 30* 的薄膜具有最大的磁电阻（MR）比，为6.2%，但随着退火时间的延长，MR比逐渐减小。（<Cu>2）场灵敏度的提高：在FeCo薄膜上沉积了软磁颗粒Fe-SiO_2层，提高了场灵敏度。

For application of spin valve elements to a new electromechanical transducer, basic investigations were carried out and the following results were obtained.1. Large exchange interaciton fields. H_<ex> were obtained in MnPt/FeCo bilayrs.i) In Cu/FeCo/MnPt films, the maximum H_<ex> appears for the MnPt film with Mn content of 51 at% after annealing. In this case, the resistivity and the blocking temperature of the Mn_<51>Pt_<49> films are about 255 muOMEGA cm and 300 - 370ﾟC,repectively.ii) On annealing of FeCo/MnPt bilayrs, the CuAu-I type fct ordered MnPt crystals grow, causing the increase in H_<ex> above 230ﾟC and then reaching the maximum of 286 - 356 Oe at 320ﾟC.Above 350ﾟC,the value of H_<ex> decreases because of inter-diffusion at the layr boundaries, which was confirmed by RBS.In order to prevent the inter-diffusion, we deposited a thin Ag layr between FeCo and MnPt layrs, which brought an improvement in the thermal stability.2. Spin valve films having high field-sensitivity and good thermal stability were obtained.i) Thermal stability of FeCo (50*) /Cu(t_<Cu>) /FeCo (35*) /MnPt (300*) films : The film of t_<Cu> = 30* shows the maximum magnetoresistance (MR) ratio, 6.2%, after annealing at 290ﾟC.However, the value of MR ratio decreases during annealing for long time. On the other hand, the films of t_<Cu> >= 40* are stable up to 320ﾟC.ii) Enhancement of the field sensitivity : Soft magnetic granular Fe-SiO_2 layr was deposited on the FeCo fre layr and the field sensitivity was increased.