Magneto-optic studies of ZnO based magnets

ZnO基磁体的磁光研究

• 批准号: EP/D070406/1
• 负责人: Gillian Gehring
• 金额: $ 39.26万
• 依托单位: University of Sheffield
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2006
• 资助国家: 英国
• 起止时间: 2006 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FD070406%2F1
• 关键词: Magneto; optic; studies; ZnO; based

Zinc oxide is a transparent crystal that does not conduct electricity. It is not magnetic.Recently it has been found that if one in 50 of the Zn atoms is replaced by a manganese or cobalt atom and the material has additional defects that add electrons that cause it to conduct electricity then it becomes magnetic at room temperature. Magnetism comes from the electrons that are associated with the magnetic atoms.Of course there are other room temperature magnets such as iron but they are metals. A magnetic semiconductor is something really new and exciting. Such a material has many applications in new devices that combine the memory capabilities of a magnet with semiconductor electronics. The magnetism arises from the widely separated magnetic atoms that line up to make one big magnet. Some of the electrons are stuck around the defects and some are free to move. An electron that is stuck near a defect may only be sensitive to the magnetism of one of the localised magnetic atoms. The electric current comes from those that are free to move and it is these electrons that will move past many magnetic atoms and cause the magnetic moments on the individual magnetic ions to line up. This happens because all electrons actually have their own little magnetic moment.Sheffield WORLD LEADING experiments show that the band edge transitions of ZnO films have a magnetic signature when doped with any one of vanadium, titanium, cobalt or manganese. This is the first clear and unambiguous demonstration that the conduction electrons of ZnO are magnetic and hence that that ZnO is a dilute magnetic semiconductor. This proposal is to use the apparatus and expertise in Sheffield to use magneto-optic spectra, absorption spectra, Hall effect measurement of the free carrier density and SQUID magnetisation measurements to establish the magnitude of the conduction electron polarisation and the nature of the ferromagnetism.This has enormous implications because it shows that the bulk magnetism observed at room temperature is really connected with the ZnO. It also opens the way for the exploitation of the storage capacity associated with the magnetism to be integrated with ultra violet light, that has a very small wavelength, this will allow a much higher density of information to be recorded and read than is currently possible with the standard lasers that use red light. We have made the first groundbreaking experiments in this area. What is needed now is to build on the understanding that we have developed. We want to extend the experimental technique to include the absorption of light as well as the response of the light to the magnetism. We want to use the method that we have developed to make the detailed studies of the behaviour of the doped ZnO films with different concentrations of dopants, different thicknesses and different temperatures. We need the grant to start on 1 April so that we can employ the research fellow who has built the apparatus that we use and also taken all the measurements so far. If there is a delay and we lose this continuity we shall lose our world leading position...

氧化锌是一种不导电的透明晶体。最近发现，如果50个锌原子中有一个被锰或钴原子取代，并且材料具有额外的缺陷，这些缺陷增加了电子，使其导电，那么它在室温下就具有磁性。磁性来自与磁性原子相关的电子。当然还有其他室温磁体，如铁，但它们是金属。磁性半导体是一种非常新颖和令人兴奋的东西。这种材料在将磁铁的记忆能力与半导体电子学结合在一起的联合收割机的新设备中有许多应用。磁性来自于排列成一个大磁铁的分散的磁性原子。有些电子被困在缺陷周围，有些则可以自由移动。一个电子卡在缺陷附近，可能只对其中一个局部磁性原子的磁性敏感。电流来自那些可以自由移动的电子，正是这些电子将移动经过许多磁性原子，并导致单个磁性离子上的磁矩排成一行。谢菲尔德世界领先的实验表明，当掺杂钒、钛、钴或锰中的任何一种时，ZnO薄膜的带边跃迁具有磁性特征。这是第一次清楚明确地证明ZnO的传导电子是磁性的，因此ZnO是一种稀磁半导体。该方案是利用谢菲尔德的仪器和专业知识，利用磁光光谱、吸收光谱、自由载流子密度的霍尔效应测量和SQUID磁化强度测量来确定传导电子极化的大小和铁磁性的性质，这具有巨大的意义，因为它表明在室温下观察到的体磁性确实与ZnO有关。它还为利用与磁性相关的存储容量开辟了道路，将其与波长非常小的紫外光集成在一起，这将允许记录和读取比目前使用红光的标准激光器更高的信息密度。我们在这一领域进行了第一次开创性的实验。现在需要的是在我们已经达成的谅解的基础上再接再厉。我们想扩展实验技术，包括光的吸收以及光对磁性的响应。我们希望使用我们已经开发的方法来详细研究具有不同掺杂剂浓度、不同厚度和不同温度的掺杂ZnO薄膜的行为。我们需要从4月1日开始拨款，以便我们可以雇用研究员，他已经建造了我们使用的仪器，并进行了迄今为止的所有测量。如果出现延误，我们失去了这种连续性，我们将失去我们的世界领先地位。

项目成果

Magnetic properties of In 2 O 3 containing Fe 3 O 4 nanoparticles

含Fe 3 O 4 纳米颗粒的In 2 O 3 的磁性能

• DOI: 10.1103/physrevb.90.144433
• 发表时间: 2014
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Alshammari M