Magnetic phase transitions in two-dimensional films

二维薄膜中的磁相变

• 批准号: 41962-2012
• 负责人: Venus, David
• 金额: $ 1.46万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568877
• 关键词: Magnetic; phase; transitions; two; dimensional

Even though everything has three spatial dimensions, in some cases the third dimension is so small that an object acts precisely as if it is two-dimensional. An example of this is the magnetic behaviour of an ultrathin film. A film of magnetic atoms, such as iron or nickel, that is only one atom thick can be deposited on a substrate that is non-magnetic. The magnetic behaviour of the film is profoundly affected by its two-dimensionality, especially with regard to the possible stable magnetic states, their orientation, and range of stability as the temperature is changed. This proposal aims to study magnetism in two-dimensional ultrathin magnetic films grown in ultrahigh vacuum and probed by magneto-optical interactions between the film magnetism and laser light. Specific projects involve fabricating and studying phase transitions in ferromagnetic films with no preferred direction of magnetization, with patterns of magnetic domains, and in antiferromagnetic films. The unique properties of ultrathin magnetic films have been essential in the development of modern data storage systems, such as computer hard discs and read heads for hard discs. They also provide a relatively convenient way to understand and describe two dimensional systems in general. This is very important for the development of many materials with novel, potentially useful, properties. One example is the whole area of nanoscale systems, where the shrinking of the size of fabricated objects often introduces aspects of two-dimensional behaviour. Another is a large class of three-dimensional materials, such as high temperature superconductors, that are composed of many parallel planes of atoms that are almost independent. Most theories rely on two-dimensional behaviour to attempt to explain why these crystals have such a low resistance to current.

尽管一切事物都具有三个空间维度，但在某些情况下，第三个维度非常小，以至于物体的行为就像二维一样。 超薄膜的磁性行为就是一个例子。只有一个原子厚的磁性原子薄膜，例如铁或镍，可以沉积在非磁性基底上。 薄膜的磁性行为深受其二维性的影响，特别是在温度变化时可能的稳定磁态、它们的方向和稳定范围方面。 该提案旨在研究在超高真空中生长的二维超薄磁性薄膜中的磁性，并通过薄膜磁性与激光之间的磁光相互作用进行探测。 具体项目涉及制造和研究没有首选磁化方向、具有磁畴图案的铁磁薄膜以及反铁磁薄膜中的相变。 超薄磁性薄膜的独特性能对于现代数据存储系统（例如计算机硬盘和硬盘读取头）的开发至关重要。 它们还提供了一种相对方便的方法来理解和描述一般的二维系统。 这对于开发许多具有新颖、潜在有用特性的材料非常重要。 一个例子是纳米级系统的整个领域，其中制造物体尺寸的缩小通常会引入二维行为的各个方面。 另一类是一大类三维材料，例如高温超导体，它们由许多几乎独立的平行原子平面组成。 大多数理论依靠二维行为来试图解释为什么这些晶体具有如此低的电流电阻。