报告人:Prof. R. E. Camley, Center for Magnetism and Magnetic Nanostructures, University of Colorado at Colorado Springs, USA
邀请人:翟亚
时间:2012年10月26日下午15:40
地点:纪中楼YF-101
摘要:
We give an overview of the properties and uses for spin waves. Their frequencies typically are in the 100 MHz to 2 THz range. They interact strongly with electromagnetic waves and this can lead to very unusual effects. For example reflection of microwaves (or infra-red radiation) from magnetic materials can be nonreciprocal. This means the reflection in one direction can be large (80%) but just reversing the direction of the input and reflected waves can lead to a very small reflection (10%). This is like creating a diode-like behavior for microwaves. We also discuss the surprising effect where spin waves can be focused and avoid the diffraction limit. Unlike normal lenses, the focusing direction can be changed by an applied magnetic field.
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