ELASTIC AND INELASTIC ELECTRON TUNNELING IN MAGNETIC METAL/MAGNETIC LAYERED SEMICONDUCTOR HETEROJUNCTIONS

研究了具有铁磁金属电极和/或反铁磁绝缘层的金属/绝缘层/金属（MIM）结中的弹性和非弹性电子隧穿（IET）。绝缘层是从层状半导体的单晶、用于反铁磁层的过渡金属硫族磷酸盐和用于非铁磁层的III-VI族化合物中劈裂的单晶薄膜。几个在两个铁磁Fe电极之间夹有MnPS_3反铁磁绝缘层的MIM结在电流-电压特性上显示出隧道电流，尽管这些结实际上具有与结中隧道电流路径并联和/或串联的金属电流路径。（a）Pb/MnPSe_3/Pb结的隧穿特性表明了隧穿电子与MnPSe_3反铁磁振子和MnPSe_3声子之间的相互作用。(b)Sb/GaS/Sb和Sb/GaS/Pb结的隧穿谱都反映了半金属Sb的能带结构。由于Sb的费米面小，对称Sb/GaS/Sb结中Sb声子和GaS声子的IET过程比不对称Sb/GaS/Pb结中的小。(c)首次在Al/GaS/Pb结的隧穿特性中观察到Al的自能效应。此外，从Ag/GaS/Pb和Cu/GaS/Pb结的隧穿谱中还推测了Ag和Cu的自能效应。(d)In <2/3> PS3单晶的光学吸收光谱显示出间接吸收边。从谱图中约化了In_（2/3）PS_3中激子带隙和动量守恒声子的能量。

We have studied elastic and inelastic electron tunneling (IET) in metal/insulator/metal (MIM) junctions having ferromagnetic metal electrodes and/or antiferromagnetic insulating layrs. The insulating layrs are single crystal thin films cleaved from the single crystals of layred semiconductors, transition metal chalcogeno-phosphates for antiferromagnetic layrs and III-VI compounds for nonmagnetic layrs. Several MIM junctions with an MnPS_3 antiferromagnetic insulating layr sandwiched between two ferromagnetic Fe electrodes show tunnel current in current-voltage characteristics, although the junctions have effectively the metallic current paths parallel and/or series to tunnel current paths in the junctions. Moreover, some additional informations about tunneling phenomena in MIM junctions were also obtained :(a) The tunneling characteristics in Pb/MnPSe_3/Pb junctions show the interactions between tunneling electrons and MnPSe_3 antiferromagnetic magnons as well as MnPSe_3 phonons.(b) Both tunneling spectra for Sb/GaS/Sb and Sb/GaS/Pb junctions reflect band structures in semimetallic Sb. The IET processes due to Sb phonons as well as GaS ones in the symmetrical Sb/GaS/Sb junctions are reduced due to small Fermi surfaces of Sb compared with those in the asymmetrical Sb/GaS/Pb junctions.(c) Self energy effects of Al are observed for the first time in the tunneling characteristics in Al/GaS/Pb junctions. Furthermore, self enrgy effects of Ag and Cu are inferred from the tunneling spectra for Ag/GaS/Pb and Cu/GaS/Pb junctions.(d) The optical absorption spectra of In_<2/3>PS_3 single crystals show an indirect absorption edge. The energy values of the exciton gap and those of the momentum conserving phonons in In_<2/3>PS_3 are reduced from the spectra.