TITLE

Curie temperatures of CoPt ultrathin continuous films

AUTHOR(S)
Cai, Wupeng; Muraishi, Shinji; Shi, Ji; Nakamura, Yoshio; Liu, Wei; Yu, Ronghai
PUB. DATE
June 2012
SOURCE
Applied Physics A: Materials Science & Processing;Jun2012, Vol. 107 Issue 3, p519
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
The effects of layer thickness and thermal annealing on Curie temperature have been studied for CoPt ultrathin continuous layers in AlN/CoPt multilayer structures. It is found that there exists a critical thickness below which Curie temperature rapidly decreases due to the loss of spin-spin interactions in the vicinity of interface. After high temperature annealing, the in-plane lattice constant of CoPt film is increased and the exchange coupling parameter is decreased. Consequently, Curie temperatures decrease for some films with large thickness, compared with as-deposited state. Upon annealing at 600 C, CoPt undergoes ordering transformation, which also contributes to the degradation of the Curie temperature. However, when the CoPt film thickness is below 2 nm, the Curie temperature is increased after annealing. Especially for 1 nm thick film, the Curie temperature is strikingly increased from 173 C to 343 C after annealing at 600 C. This effect is attributed to the out-of-plane lattice deformation of CoPt thin layers in AlN/CoPt multilayer structures.
ACCESSION #
75231210

 

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