清华大学材料科学与工程研究院《材料科学论坛》

学术报告

题目：

Magnetic and transport properties of Ga_1-xMn_xAs diluted magnetic semiconductors studied in magnetic fields up to 50 Tesla

报告人：

Dr. J. Vanacken

（Pulsed Field Group, Institute for Nanoscale Physics and Chemistry,, K.U.Leuven, Celestijnenlaan 200D, 3001 Leuven,  Belgium）

时间：

2009年5月12日（星期二） 10：30

地  点：

清华大学材料院学术报告厅（逸夫技术科学楼2－321）

联系人：章晓中 教授 62773999

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Magnetic and transport properties of Ga_1-xMn_xAs diluted magnetic semiconductors studied in magnetic fields up to 50 Tesla.

Dr  J. Vanacken

Pulsed Field Group, Institute for Nanoscale Physics and Chemistry,, K.U.Leuven, Celestijnenlaan 200D, 3001 Leuven,  Belgium

The successful growth of ferromagnetic Ga_1-xMn_xAs films using low temperature molecular beam epitaxy and the relatively high Curie temperature (T_C) up to 110K that could be obtained, attracted a lot of interest for this material from both a fundamental and an applied point of view. The ferromagnetism which is observed in Ga_1‑xMn_xAs does not only open prospects for spintronics applications, but also raises questions about the nature of the magnetic interactions that lead to ferromagnetic ordering in these materials.

We will present the effect of low temperature annealing on the magnetic and transport properties of Ga_1‑xMn_xAs to gain information about the annealing mechanisms and the physics of diluted magnetic semiconductors.  We will test some recent theoretical models on resistivity data obtained on a series of Ga_1‑xMn_xAs films with various Mn contents and from Hall effect measurements in pulsed magnetic fields up to 50T we will obtain values for the hole density as a function of the Mn content, with a reasonable accuracy. A detailed study of the magnetization measurements along the main crystallographic directions of a Ga_1‑xMn_xAs (x = 0:08) sample reveals a rich temperature dependent magnetic anisotropy behavior which changes with temperature and can be altered with a post-growth annealing treatment.