[7p-PB4-1~12] 13.2 探索的材料物性・基礎物性

[7p-PB4-11] [Fe₃Si/FeSi₂]₂₀ 人工格子の磁気構造

〇花島 隆泰¹、竹市 悟志²、宮田 登¹、堺 研一郎³、出口 博之⁴、吉武 剛² (1.CROSS、2.九大総理工、3.久留米高専、4.九工大工)

キーワード：偏極中性子反射率、磁気構造、層間結合

Since the discovery of a giant magnetoresistance (GMR) effect associated with an exchange coupling between ferromagnetic layers separated by a nonmagnetic metal spacer, the interlayer coupling has attracted considerable attention from physical and practical viewpoints. The interlayer coupling is described by spin-dependent quantum well states in the spacer. In the case of non-metallic spacers, there often appears a different type of interlayer coupling from that in artificial lattices with metallic spacers. An artificial lattice comprised of Fe-Si materials is one of the representatives. To date, Fe/Si and Fe/Fe_1-xSi_x multilayers have been studied. In them, strong antiferromagnetic (AF) interlayer couplings including biquadratic ones, which are different from those in artificial lattices with metallic spacers, are induced. We have conducted research on Fe₃Si/FeSi₂ artificial lattices. As compared to the previous artificial lattices based on Fe-Si materials, they have the following advantages: (i) a reduced mismatch in the electrical conductivity; (ii) a strong AF interlayer coupling strength in spite of the saturation magnetization of Fe₃Si being half as that of Fe. In our previous research, we have confirmed that the Fe₃Si layers were epitaxially grown not only on Si(111) but also up to the top layer across the FeSi₂ layers and F/AF interlayer couplings were induced by controlling the thickness of the FeSi₂ layers. In this study, the interlayer coupling in Fe₃Si/FeSi₂ artificial lattices deposited on Si(111) by facing targets direct-current sputtering (FTDCS) was investigated at low temperatures.
However, the magnetic structures of F/AF interlayer couplings are not clarified. So, we will present magnetic structure which depends on temperature and thickness of semiconductor FeSi₂ layer. The polarized neutron reflectivity (PNR) spectrum of the [Fe₃Si/FeSi₂]₂₀ superlattices is measured by applying a magnetic field of 1.0 Tesla at Polarized Neutron Reflectometor “SHARAKU” (BL17) in MLF J-PARC. The PNR spectrum reveals the magnetic structures of these superlattices, as shown in Fig. 1. We will indicate the magnetic structure of the superlattice in detail at the conference.