Magneto-optic studies of ZnO based magnets

ZnO基磁体的磁光研究

基本信息

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

项目摘要

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。它没有磁性。已经发现，如果50个锌原子中的一个被锰或钴原子代替，并且该材料具有额外的缺陷，添加电子可导致电力导致电力，那么它在室温下会磁性。磁性来自与磁原子相关的电子。当然还有其他室温磁铁，例如铁，但它们是金属。磁性半导体是真正的新事物。这种材料在新设备中具有许多应用，可以将磁铁的存储能力与半导体电子设备相结合。磁性源于将一个大磁铁排成一列的广泛分开的磁原子。一些电子被困在缺陷周围，有些电子可以自由移动。被困在缺陷附近的电子可能仅对局部磁原子之一的磁性敏感。电流来自可以自由移动的电流，正是这些电子将经过许多磁原子并导致单个磁离子上的磁矩对齐。之所以发生这种情况，是因为所有电子实际上都有自己的小磁矩。SheftieldWorld领先实验表明，当与钒，钛，钴或锰的任何一个掺杂时，ZnO膜的带边缘过渡具有磁性特征。这是第一个明确而明确的证明，ZnO的传导电子是磁性的，因此ZnO是稀释的磁性半导体。该建议是利用谢菲尔德的设备和专业知识来使用磁光谱，吸收光谱，霍尔效应测量自由载体密度和鱿鱼磁化测量值来确定传导电子极化的幅度以及富特磁性的性质，因为它在摩恩群岛上均具有巨大的含义，因为它在摩恩群岛上均具有巨大的含义。它还为与磁性相关的储存能力与超紫色光集成相关的存储容量开辟了道路，其波长很小，这将使与使用红光的标准激光器相比，将记录和读取的信息密度比当前更高。我们在该领域进行了第一个开创性实验。现在需要的是建立我们已经发展的理解。我们希望扩展实验技术，以包括光的吸收以及光对磁力的响应。我们想使用我们开发的方法来详细研究具有不同浓度的掺杂剂，不同厚度和不同温度的掺杂ZnO膜的行为。我们需要赠款从4月1日开始，以便我们可以聘请建立我们使用的设备的研究员，并迄今为止采用所有测量。如果有延迟，我们失去了这种连续性，我们将失去世界领先地位...