S. Takeyama
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
S. Takeyama has a total of 33 co-authors. Here are the top co-authors by number of shared publications:
G. Karczewski
Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
3 shared publications- H. Yokoi
National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan
3 shared publications - Jacek Kossut
Institute of Physics, Polish Academy of Sciences
3 shared publications S. Adachi
Department of Material Science, Faculty of Science, Himeji Institute of Technology, 1479-1 Kamigori
3 shared publications- Thomasz Wojtowicz
Polish Academy of Sciences
3 shared publications Y. Takagi
Department of Material Science, Faculty of Science, Himeji Institute of Technology, 1479-1 Kamigori
3 shared publications
Latest Publications
- 25 October 2002
- Published by IOP Publishing in Journal of Physics: Condensed Matter
- Vol. 14 (44) , 11001-11006
High-pressure and high-magnetic-field study of energy transfer from excitons into local d electrons in a CdTe/(Cd, Mn)Te quantum well structure
Photoluminescence measurements have been conducted for a CdTe/Cd1-xMnx Te (x = 0.4) single-quantum-well structure at low temperatures under pressures to 0.49 GPa and magnetic fields to 60 T. At the ambient pressure, a new emission was induced by the application of a magnetic field. The emission has been assigned to exciton emission from the barrier layer, which is suppressed below 9 T due to the energy transfer from the exciton to local d electrons. At 0.49 GPa, the emission recovered at 44 T. In the field region where the energy transfer occurs, an anomalous red-shift of the exciton energy was observed clearly for the case of the ambient pressure. The alloy potential fluctuation effect and the magnetopolaron effect are examined as candidates for the mechanism to cause this phenomenon.
- 25 October 2002
- Published by IOP Publishing in Journal of Physics: Condensed Matter
- Vol. 14 (44) , 11001-11006
High-pressure and high-magnetic-field study of energy transfer from excitons into local d electrons in a CdTe/(Cd, Mn)Te quantum well structure
Photoluminescence measurements have been conducted for a CdTe/Cd1-xMnx Te (x = 0.4) single-quantum-well structure at low temperatures under pressures to 0.49 GPa and magnetic fields to 60 T. At the ambient pressure, a new emission was induced by the application of a magnetic field. The emission has been assigned to exciton emission from the barrier layer, which is suppressed below 9 T due to the energy transfer from the exciton to local d electrons. At 0.49 GPa, the emission recovered at 44 T. In the field region where the energy transfer occurs, an anomalous red-shift of the exciton energy was observed clearly for the case of the ambient pressure. The alloy potential fluctuation effect and the magnetopolaron effect are examined as candidates for the mechanism to cause this phenomenon.
- 15 March 1999
- Published by American Physical Society (APS) in Physical Review B
- Vol. 59 (11) , 7327-7329
Zeeman-gap anomaly in photoluminescence from a two-dimensional electron gas in CdTe/(Cd, Mg)Te quantum wells
We have investigated photoluminescence spectra from a two-dimensional electron gas in a n-type single quantum well in magnetic fields up to 14 T at low temperatures. High-mobility two-dimensional carriers in this system exhibited photoluminescence oscillation and splitting in accordance with the Landau filling factor. The pronounced spectral anomaly especially near at odd filling factor suggests the importance of the spin degree of freedom. The observed spectra exhibited the behavior predicted by a calculation by Hawrylak and Potemski [Phys. Rev. B 56, 12 386 (1997)] taking account of Auger and spin-flip recombination processes. Temperature as well as excitation power dependence of this anomalous photoluminescence peaks was investigated.- 15 March 1999
- Published by American Physical Society (APS) in Physical Review B
- Vol. 59 (11) , 7327-7329
Zeeman-gap anomaly in photoluminescence from a two-dimensional electron gas in CdTe/(Cd, Mg)Te quantum wells
We have investigated photoluminescence spectra from a two-dimensional electron gas in a n-type single quantum well in magnetic fields up to 14 T at low temperatures. High-mobility two-dimensional carriers in this system exhibited photoluminescence oscillation and splitting in accordance with the Landau filling factor. The pronounced spectral anomaly especially near at odd filling factor suggests the importance of the spin degree of freedom. The observed spectra exhibited the behavior predicted by a calculation by Hawrylak and Potemski [Phys. Rev. B 56, 12 386 (1997)] taking account of Auger and spin-flip recombination processes. Temperature as well as excitation power dependence of this anomalous photoluminescence peaks was investigated.- 1 January 1998
- Published by The Japan Society of High Pressure Science and Technology in The Review of High Pressure Science and Technology
- Vol. 7, 766-768
High Magnetic Field Photoluminescence Study of Pressure Effect on Spin Exchange Interaction in a CdTe/Cd1-xMnxTe Single Quantum Well Structure.
Photoluminescence (PL) measurements in CdTe/Cd1-xMnx Te (x=0. 24) single quantum well (SQW) structure with different quantum well (QW) widths and bulk Cd1-xMnxTe (x=0. 15) under high hydrostatic pressures up to 2. 68 GPa and DC magnetic fields up to 30 T are reported. We analyze the Zeeman shift of the band-edge exciton PL peaks, taking into account a linear magnetization term, and obtain pressure dependence of spin exchange parameters. Negative pressure dependence of the p-d hybridization is found for the barrier of the SQW structure and the bulk sample. A possibility that the hybridization is weakened due to the pressure induced relaxation of the distortion around Te atoms is proposed.
- 1 January 1998
- Published by The Japan Society of High Pressure Science and Technology in The Review of High Pressure Science and Technology
- Vol. 7, 766-768
High Magnetic Field Photoluminescence Study of Pressure Effect on Spin Exchange Interaction in a CdTe/Cd1-xMnxTe Single Quantum Well Structure.
Photoluminescence (PL) measurements in CdTe/Cd1-xMnx Te (x=0. 24) single quantum well (SQW) structure with different quantum well (QW) widths and bulk Cd1-xMnxTe (x=0. 15) under high hydrostatic pressures up to 2. 68 GPa and DC magnetic fields up to 30 T are reported. We analyze the Zeeman shift of the band-edge exciton PL peaks, taking into account a linear magnetization term, and obtain pressure dependence of spin exchange parameters. Negative pressure dependence of the p-d hybridization is found for the barrier of the SQW structure and the bulk sample. A possibility that the hybridization is weakened due to the pressure induced relaxation of the distortion around Te atoms is proposed.
- 15 January 1997
- Published by American Physical Society (APS) in Physical Review B
- Vol. 55 (3) , 1654-1660
Polarization choices in exciton-biexciton system of GaAs quantum wells
We study the induced absorption due to biexciton formation in absorption bleaching pump-probe signals and the quantum beats between exciton and biexciton in the four-wave-mixing signals. The origin is confirmed by the polarization dependence of the signals in both experiments. The definite discrimination between exciton-biexciton quantum beats and the others by the polarization choices is demonstrated clearly. We also show the well-width dependence of the biexciton binding energy that is determined by the period of the quantum beats in the range of well width 45–150 Å of GaAs/ As (x=0.3–1.0) multiple quantum wells.- 15 January 1997
- Published by American Physical Society (APS) in Physical Review B
- Vol. 55 (3) , 1654-1660
Polarization choices in exciton-biexciton system of GaAs quantum wells
We study the induced absorption due to biexciton formation in absorption bleaching pump-probe signals and the quantum beats between exciton and biexciton in the four-wave-mixing signals. The origin is confirmed by the polarization dependence of the signals in both experiments. The definite discrimination between exciton-biexciton quantum beats and the others by the polarization choices is demonstrated clearly. We also show the well-width dependence of the biexciton binding energy that is determined by the period of the quantum beats in the range of well width 45–150 Å of GaAs/ As (x=0.3–1.0) multiple quantum wells.- 1 November 1995
- Published by Institute of Physics, Polish Academy of Sciences in Acta Physica Polonica A
- Vol. 88 (5) , 945-948
Exciton Magneto-Optical Study on Single Quantum Wells, Cd1-xZnxTe/Cd1-x'-yZnx'MnyTe
- 1 November 1995
- Published by Institute of Physics, Polish Academy of Sciences in Acta Physica Polonica A
- Vol. 88 (5) , 945-948
Exciton Magneto-Optical Study on Single Quantum Wells, Cd1-xZnxTe/Cd1-x'-yZnx'MnyTe
- 15 February 1995
- Published by American Physical Society (APS) in Physical Review B
- Vol. 51 (8) , 4858-4864
Exciton localization by magnetic polarons and alloy fluctuations in the diluted magnetic semiconductor TePhotoluminescence was measured on the diluted magnetic semiconductor alloys Te with 0.1<x<0.35, at temperatures between 4.2 and 60 K. Detailed line-shape analysis of the exciton luminescence is carried out to show the temperature dependence of peak positions, integrated intensities, line broadening, and asymmetry of the spectral shape. The luminescence intensity of the so-called line grows abruptly at low temperatures, and is attributed to exciton localization caused either by exciton magnetic polarons (EMP’s) or alloy potential fluctuations (APF’s). Only the lowest possible laser-power excitation enables us to observe the effect caused by the former. The characteristic line shape, especially the asymmetry of the luminescence line, is discussed in accordance with a type of localization: EMP’s or APF’s. We have determined the binding energies of localization from EMP’s and APF’s, as a function of Mn alloy concentrations. The results are compared with existing theories. It is found that the EMP energy depends on the cube of the number of Mn isolated local spins, and EMP formation is barely realized at x>0.20, and most stable at 0.05<x<0.1. We found that the primary localization due to APF’s is not necessary for EMP formation, but that the possibility of spin-fluctuation localization still remains.- 15 February 1995
- Published by American Physical Society (APS) in Physical Review B
- Vol. 51 (8) , 4858-4864
Exciton localization by magnetic polarons and alloy fluctuations in the diluted magnetic semiconductor TePhotoluminescence was measured on the diluted magnetic semiconductor alloys Te with 0.1<x<0.35, at temperatures between 4.2 and 60 K. Detailed line-shape analysis of the exciton luminescence is carried out to show the temperature dependence of peak positions, integrated intensities, line broadening, and asymmetry of the spectral shape. The luminescence intensity of the so-called line grows abruptly at low temperatures, and is attributed to exciton localization caused either by exciton magnetic polarons (EMP’s) or alloy potential fluctuations (APF’s). Only the lowest possible laser-power excitation enables us to observe the effect caused by the former. The characteristic line shape, especially the asymmetry of the luminescence line, is discussed in accordance with a type of localization: EMP’s or APF’s. We have determined the binding energies of localization from EMP’s and APF’s, as a function of Mn alloy concentrations. The results are compared with existing theories. It is found that the EMP energy depends on the cube of the number of Mn isolated local spins, and EMP formation is barely realized at x>0.20, and most stable at 0.05<x<0.1. We found that the primary localization due to APF’s is not necessary for EMP formation, but that the possibility of spin-fluctuation localization still remains.- Open Access
- 1 February 1991
- Published by Institute of Physics, Polish Academy of Sciences in Acta Physica Polonica A
- Vol. 79 (2) , 363-367
Hight-Field Submillimeter Magneto-Spectroscopy on Hg(Fe)Se
- 1 February 1991
- Published by Institute of Physics, Polish Academy of Sciences in Acta Physica Polonica A
- Vol. 79 (2) , 363-367
Open AccessHight-Field Submillimeter Magneto-Spectroscopy on Hg(Fe)Se