DEVELOPMENT OF A NEW ELECTROMECHANICAL TRANSDUCER USING SPIN VALVE ELEMENTS

为了将自旋阀元件应用于一种新型的机电换能器，进行了基础研究，取得了以下结果。较大的交换交互字段。在Cu/FeCo/MnPt薄膜中，当Mn含量为51at%时，退火后薄膜的H&lt；ex&gt；出现最大值。在这种情况下，薄膜的电阻率和阻挡温度分别约为255muOmega cm和300-370ﾟC。ii)在FeCo/MnPt双层薄膜的退火过程中，CuAu-I型FCT有序的MnPT晶体生长，导致H&lt；ex&gt；增加到230ﾟC以上，然后在320ﾟC时达到最大值286-356Oe。为了防止这种互扩散，我们在FeCo和MnPt层之间沉积了一层很薄的银层，从而提高了热稳定性。I)FeCo(50*)/Cu(t&lt；Cu&gt；)/FeCo(35*)/MnPt(300*)薄膜的热稳定性：当t&lt；Cu&gt；=30*时，薄膜的磁阻(MR)值最大，在290ﾟC时为6.2%。另一方面，t_&lt；Cu&gt；&gt；=40*薄膜在320ﾟC以下保持稳定。ii)场灵敏度的提高：在FeCo薄膜上沉积了软磁颗粒状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.