Observation of e2/h conductance steps in a side-gate point contact on In0.75Ga0.25As/In0.75Al0.25As heterostructure

In 1996, it was suggested by K.J. Thomas et al. (Phys. Rev. Lett. 77, 135 (1996)) that 0.7(2e(2)/h) conductance structure in Quasi-1DEG (Q1DEG) at GaAs/AlGaAs heterostructure might be related to spin polarization at zero magnetic field. We have recently studied spontaneous spin-splitting in the 2DEGs formed at normal metamorphic In0.75Ga0.25As/In0.75Al0.25As heterojunctions grown on GaAs substrates and obtained the value of less than or similar to10 meV as the zero-field splitting at Fermi level (Y. Sato et al., J. Appl. Phys. 89, 8017 (2001)). In this work, we attempted to observe spin-related phenomena in this heterojunction Q1DEGs at zero magnetic field. We observed e(2)/h conductance steps in low electron concentration side-gate point contact.