Spin-on Spintronics: Ultrafast Electron Spin Dynamics in ZnO and Zn1-xCoxO Sol-Gel Films

被引：42

作者：

Whitaker, Kelly M. ^{[1
,2
,3
]}

Raskin, Maxim ^{[2
,3
]}

Kiliani, Gillian ^{[2
,3
]}

Beha, Katja ^{[2
,3
]}

Ochsenbein, Stefan T. ^{[1
]}

Janssen, Nils ^{[1
,2
,3
]}

Fonin, Mikhail ^{[2
,3
]}

Ruediger, Ulrich ^{[2
,3
]}

Leitenstorfer, Alfred ^{[2
,3
]}

Gamelin, Daniel R. ^{[1
]}

Bratschitsch, Rudolf ^{[2
,3
]}

机构：

[1] Univ Washington, Dept Chem, Seattle, WA 98195 USA

[2] Univ Konstanz, Dept Phys, D-78464 Constance, Germany

[3] Univ Konstanz, Ctr Appl Photon, D-78464 Constance, Germany

来源：

NANO LETTERS | 2011年 / 11卷 / 08期

基金：

美国国家科学基金会;

关键词：

ZnCoO; sol-gel; spin dynamics; hole trapping; exchange energy; time-resolved Faraday rotation; QUANTUM DOTS; EXCHANGE; SEMICONDUCTORS; FERROMAGNETISM; EXCITONS;

D O I：

10.1021/nl201736p

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

We use time-resolved Faraday rotation spectroscopy to probe the electron spin dynamics in ZnO and magnetically doped Zn1-xCoxO sol gel thin films. In undoped ZnO, we observe an anomalous temperature dependence of the ensemble spin dephasing time T-2*, i.e., longer coherence times at higher temperatures, reaching T-2* similar to 1.2 ns at room temperature. Time-resolved transmission measurements suggest that this effect arises from hole trapping at grain surfaces. Deliberate addition of Co2+ to ZnO increases the effective electron Lande g factor, providing the first direct determination of the mean-field electron-Co2+ exchange energy in Zn1-xCoxO (N-0 alpha = +0.25 +/- 0.02 eV). In Zn1-xCoxO, T-2* also increases with increasing temperature, allowing spin precession to be observed even at room temperature.

引用

页码：3355 / 3360

页数：6

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