Dimensionality-dependent magnetic behavior in transition metal films
Abstract
The critical temperatures of itinerant magnets shift to lower temperatures than that of the bulk with decreasing film thickness (n monolayers). This `finite-size effect' is modified when the film thickness begins to approach an intrinsic spin-spin correlation length characteristic of the material [1]. The shift of the Curie temperature t(n) = 1 - Tc(n)/Tc(bulk) follows a power law dependence crossing over to linear behavior. This crossover thickness varies from material to material. In this paper, we monitor this behavior for a range of alloys in which the density of d-hole states is varied linearly. A corresponding linear dependence is observed in this crossover behavior. A second crossover is observed in ultrathin films corresponding to a change in dimensionality from 3D to 2D behavior. This behavior is a consequence of quantization of states in the diminishing dimension and correlates with the changing dimensions of the Fermi surfaces of a range of fcc [2] and bcc alloys. [1] R. Zhang and R. F. Willis, Phys. Rev. Lett., 86(12), 2665 (2001). [2] M. Hochstrasser, N. Gilman, R. F. Willis, F. O. Schumann, J. G. Tobin and E. Rotenberg, Phys. Rev. B 60(24), 17030 (1999).
- Publication:
-
APS March Meeting Abstracts
- Pub Date:
- March 2002
- Bibcode:
- 2002APS..MARS15010G