Abstract
We investigated the temperature dependence of magnetization reversal processes of exchange-spring magnet, hard/soft ferromagnetic heterostructures. In most previous works, the thicknesses of the soft and hard layers were used as the main control parameters to investigate the reversal mechanism of the exchange-spring magnet. In our work, the anisotropy energy of the hard layer changes as a function of temperature, while the change in the magnetic properties of the soft layer is negligible in the temperature regime in which we are interested (between 10 and 300 K). The magnetic hysteresis loops of SmFe/Py (= Ni80 Fe20) and SmCo/Py exchange-spring magnets were measured at various temperatures. Magnetic reversal behaviors of SmFe/Py and SmCo/Py were explained using the parameters extracted from the single layer measurements, SmFe or SmCo films, and the existing theory, where the reversal mechanism is controlled by the thicknesses. With a proper conversion of the temperature dependent anisotropy energy to the scaled thickness scheme, the reversal mechanisms of SmFe/Py and SmCo/Py could be explained with a simple model theory for a wide range of temperatures.
| Original language | English |
|---|---|
| Article number | 103918 |
| Journal | Journal of Applied Physics |
| Volume | 107 |
| Issue number | 10 |
| DOIs | |
| State | Published - 15 May 2010 |
Bibliographical note
Funding Information:This research was supported by the Research Corporation under Contract No. CC6756 and NSF MRI Grant under Contract No. 0619909. C.Y.Y was supported by Nano R&D program through the KOSEF funded by the Ministry of Science and Technology (Grant No. 2008-02553). FIG. 1. The magnetic hysteresis loops of (a) SmFe and (b) SmCo single layers along the easy axis. The hysteresis loops were measured at 10, 50, 100, 150, 200, 250, and 300 K along the easy axes, respectively. FIG. 2. Anisotropy energy, K h , and normalized saturation magnetization, M h , as a function of temperature for SmFe (blue filled and open circles) and SmCo (red filled and open triangles) single layers. FIG. 3. The temperature dependent H h for (a) SmFe and (b) SmCo single layers. The symbols in the insets are the log scale plots of H h and the solid lines are linear fits. FIG. 4. The magnetic hysteresis loops of (a) SmFe/Py and (b) SmCo/Py exchange-spring systems for easy axes measured at various temperatures. FIG. 5. (a) d h and (b) t s / d h as a function of temperature for SmFe/Py and SmCo/Py. FIG. 6. H N Exp . / H N Theo . as a function of temperature for SmFe/Py and SmCo/Py.