Anomalous interlayer exchange coupling in CoFe/Bi/Co sandwiches
Date Issued
2006
Date
2006
Author(s)
Xue, Zhi-Long
DOI
en-US
Abstract
Magnetic coupling between two ferromagnetic layers through a spacer layer (metal, semiconductor or insulating) has been extensively studied during last several years and still attracts a lot of attention. This interaction is ferromagnetic (FM) or antiferromagnetic (AFM) depending upon spacer material and spacer thickness. For example, the interaction oscillates between FM and AFM couplings with spacer thickness for a trilayer with the metal spacer. In spite of many theoretical and experimental works devoted to this problem the origin of interlayer coupling is still under discussion. The detailed investigation of interlayer coupling as a function of temperature could provide a way to better understand the basic mechanisms involved on it; in this thesis, a series of CoFe (15 nm) / Bi (tBi) /Co (15 nm) sandwiches with tBi ranging from 1 to 56nm was prepared by dc sputtering to study the detailed temperature behavior of the interlayer exchange coupling. We performed measurements of the interlayer coupling as a function of the spacer thickness in the temperature range between 4K and 300K. It is observed that the FM coupling is persist when the temperature is decreased from 300K down to 4K whereas the AFM coupling switches to the FM coupling at low temperatures. The origin of this anomalous interlayer coupling with a Bi spacer as well as its temperature dependence is discussed in this thesis.
Subjects
層間交換耦合
準金屬
interlayer exchange coupling
semimetal
Type
thesis
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