Pump-Probe Study of Carrier-Spin Injection in a Diluted Magnetic Double Quantum Well of CdMnTe/CdTe

다국어 초록 (Multilingual Abstract)

We study the dynamics of carrier-spin injection in a diluted magnetic semiconductor double
quantum well (DMS-DQW) of CdMnTe/CdTe by means of pump-probe absorption spectroscopy.
The time dependences of the absorption saturation intensity show the injection dynamics of spinpolarized
electrons and heavy holes (hhs) from the DMS-CdMnTe into the non-magnetic CdTe
wells, where separate tunneling of the electron and the hh is directly elucidated with time constants
of 150 ps and 1 ns, respectively. The degree of circular polarization P of the absorption saturation
increases from 0 to 70 ps after pumping in the non-magnetic CdTe well, which is caused by the
injection of polarized electron spins in the DMS well. We observe a systematic dependence of the
rise time of P on the magnetic eld. The faster polarization of the electron spin in the DMS well
results in a faster electron-spin injection. The electron's spin polarization is accelerated in the DMS
well by LO-phonon scattering at 6 T, where the electron spin splitting is close to the one-LO-phonon
energy, which enables us to demonstrate a fast electron-spin injection with a time constant of 10
ps.

다국어 초록 (Multilingual Abstract)

We study the dynamics of carrier-spin injection in a diluted magnetic semiconductor double
quantum well (DMS-DQW) of CdMnTe/CdTe by means of pump-probe absorption spectroscopy.
The time dependences of the absorption saturation intensity show the injection dynamics of spinpolarized
electrons and heavy holes (hhs) from the DMS-CdMnTe into the non-magnetic CdTe
wells, where separate tunneling of the electron and the hh is directly elucidated with time constants
of 150 ps and 1 ns, respectively. The degree of circular polarization P of the absorption saturation
increases from 0 to 70 ps after pumping in the non-magnetic CdTe well, which is caused by the
injection of polarized electron spins in the DMS well. We observe a systematic dependence of the
rise time of P on the magnetic eld. The faster polarization of the electron spin in the DMS well
results in a faster electron-spin injection. The electron's spin polarization is accelerated in the DMS
well by LO-phonon scattering at 6 T, where the electron spin splitting is close to the one-LO-phonon
energy, which enables us to demonstrate a fast electron-spin injection with a time constant of 10
ps.

참고문헌 (Reference)

1 R. Fiederling, 402 : 787-, 1999

2 Y. Ohno, 402 : 790-, 1999

3 M. Oestreich, 74 : 1251-, 1999

4 W. H. Butler, 63 : 054416-, 2001

5 K. Kayanuma, 340-342 : 882-, 2003

6 W. M. Chen, 72 : 073206-, 2005

7 E. Tsitsishvili, 71 : 155320-, 2005

8 A. Murayama, 88 : 261105-, 2006

9 K. Saito, 90 : 262111-, 2007

10 K. Nishibayashi, 88 : 211108-, 2006

11 S. Schmitt-Rink, 32 : 6601-, 1985

12 W. M. Chen, 67 : 125313-, 2003

13 I. A. Buyanova, 71 : 165203-, 2005