Abstract
We have observed a superparamagnetic to ferromagnetic transition in films of isolated Ni grains covered by non-magnetic overlayers. The magnetoresistance (MR) of the films was measured as a function of the overlayer thickness. Initially, the granular Ni films exhibited negative MR curves peaked at H = 0. As different materials were deposited onto the grains hysteresis developed in the MR. This behavior is ascribed to an increase of the typical domain size because of the magnetic coupling between grains. The strength of the inter-grain coupling is found to correlate with the magnetic susceptibility of the overlayer material. We discuss possible mechanisms for this coupling and suggest that the data may reflect the existence of a magnetic proximity effect (analogous to the well-known effect in superconductivity) in which a ferromagnetic moment is induced in the metallic non-magnetic medium.
| Original language | English |
|---|---|
| Pages (from-to) | 485-490 |
| Number of pages | 6 |
| Journal | Solid State Communications |
| Volume | 110 |
| Issue number | 9 |
| DOIs | |
| State | Published - 6 May 1999 |
| Externally published | Yes |
Bibliographical note
Funding Information:We are grateful for technical help we received from T. Kirk and for illuminating discussions with D. Arovas, A.E. Berkowitz, F. Hellman, S. Sankar and H. Suhl. This research was supported by AFSOR grant no. F49620-92-j-0070.
Funding
We are grateful for technical help we received from T. Kirk and for illuminating discussions with D. Arovas, A.E. Berkowitz, F. Hellman, S. Sankar and H. Suhl. This research was supported by AFSOR grant no. F49620-92-j-0070.
| Funders | Funder number |
|---|---|
| AFSOR | F49620-92-j-0070 |