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Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*
Journal of Semiconductors, 39(8), p.082001_1 - 082001_5, 2018/08
Dynamic nuclear self-polarization (DYNASP) is a phenomenon observed in III-V semiconductors. When electrons of the valence band of a semiconductor are optically excited to the conduction band, a relaxation process of the conduction electrons induces a large nuclear polarization to suddenly occur below a critical temperature. Extending the original theoretical work of Dyakonov et al., we examined the effect of spin distribution of valence electrons excited by the circularly polarized light and the effect of external magnetic field on the phenomenon of the nuclear self-polarization. We found that the nuclear polarization is achieved even above the critical temperatures by the effect of electron polarization and of the external magnetic field. To investigate the phenomenon experimentally, we constructed an apparatus for low-temperature experiments.
Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*; Nakamura, Shoji
Nuclear Instruments and Methods in Physics Research B, 317(Part B), p.689 - 692, 2013/12
Times Cited Count：1 Percentile：11.54(Instruments & Instrumentation)Dynamic nuclear self-polarization (DYNASP) is a phenomenon that is observed in the III-V semiconductors. When electrons in the valence band of a semiconductor are optically excited to the conduction band, quite large nuclear polarization suddenly occurs below a critical temperature. This phenomenon was theoretically predicted by Dyakonov and Perel. Our recent work predicted that the electrons excited by circularly polarized laser enhance nuclear polarization near the critical temperature. The mechanism of such a large nuclear polarization would be useful for measurements of nuclear magnetic moments of unstable nuclides. However, the experiment on DYNASP can be found only in a conference report. In order to confirm the phenomenon, we have started the study of DYNASP. Preparation of experiments on DYNASP is in progress. In this paper, we describe the present status of the study of nuclear polarization by using DYNASP from the theoretical and experimental aspects.
Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*
Journal of Applied Physics, 110(1), p.013911_1 - 013911_8, 2011/07
Times Cited Count：2 Percentile：9.73(Physics, Applied)Lattice nuclei of III-V type semiconductors can be self-polarized through the contact hyperfine interaction with optically excited electrons on the conduction band at low temperatures. The effect of electrons excited with circularly polarized light is introduced to the theoretical prediction of self-polarization. We found that the degree of nuclear polarization is enhanced in comparison with the use of un-polarized light. The direction of the nuclear polarization is controlled by the orientation of the electron polarization. A hysteresis phenomenon appears in the nuclear polarization when varying the degree of electron polarization.
Koizumi, Mitsuo; Matsuki, Seishi*; Goto, Jun*
no journal, ,
no abstracts in English
Koizumi, Mitsuo; Matsuki, Seishi*; Goto, Jun*; Nakamura, Shoji
no journal, ,
no abstracts in English
Koizumi, Mitsuo; Goto, Jun*; Matsuki, Seishi*
no journal, ,
no abstracts in English
