CdS晶体电子自旋相干动力学

Electron spin coherence dynamics in CdS crystals

利用时间分辨克尔旋转(Time-Resolved Kerr Rotation, TRKR)光谱技术研究了纤锌矿n-CdS(n型掺杂)(0001)面单晶在不同温度、不同波长下的电子自旋相干动力学.发现低温下该材料存在两种电子自旋信号:一种是在较长泵浦探测波长下存在的长寿命自旋信号,低温5 K时其自旋退相位时间长达4.8 ns,随着温度的升高不断减小;另一种为较短泵浦探测波长下存在的短寿命自旋信号,其自旋退相位时间约为40 ps,可以持续到室温,该自旋信号几乎不受温度的影响.研究表明,长寿命自旋信号来自于局域电子,而短寿命自旋信号来自于导带自由电子.

In this paper, we use time-resolved Kerr rotation(TRKR) spectroscopy to study the electron spin coherence dynamics of a wurtzite(0001) plane n-CdS single crystal at different temperatures and wavelengths. Two types of electronic spin signals are observed in this material at low temperatures. One is a long-lived spin signal at relatively long pump probe wavelengths, where the spin dephasing time exceeds4.8 ns at 5 K and decreases with increasing temperature. The other is a short-lived spin signal at relatively short pump probe wavelengths, where the spin dephasing time is about 40 ps and persists up to room temperature;in this case, the spin signal is largely independent of temperature. Studies have shown that long-lived spin signals can be attributed to localized electrons, while short-lived spin signals can be attributed to conduction delocalized electrons.