Event Description
V. Cambel, PhD, Institute of Electrical Engineering, Slovak Academy of Sciences
Strong interest in nanomagnetism stems from the promise of high storage densities of information through control of ever smaller and smaller ensembles of spins. There is a broad consensus that the Landau-Lifshitz-Gilbert equation reliably describes the magnetization dynamics on classical phenomenological level. On the other hand it is not so evident that the magnetization dynamics governed by this equation contains built-in asymmetry in the case of broad topology sets of symmetric total energy functional surfaces. The magnetization dynamics in such cases shows preferences for one particular state of many energetically equivalent minima. In the theoretical part we demonstrate this behaviour on a simple one-spin model. Such simplified model is opening a possible venue for controlling magnetic states of the future nanodevices in practical applications. Using micromagnetic simulations we show the asymmetry in magnetization dynamics in a real system with reduced symmetry [1]. In the experimental part we have: 1) developed novel scanning method, dual-tip magnetic force microscopy (DT-MFM) to show magnetic state of the nanomagnets with broken symmetry, 2) explored magnetization reversal of the nanomagnet using micro-Hall probe magnetometry.
The DT-MFM imaging [2] was developed to avoid the sample touching by the magnetic tip. In the method, the topological and magnetic scans are segregated using two different tips, one magnetic and one non-magnetic. Tips are located on a cantilever cut by focused ion beam technology. The non-magnetized tip is used for the topography only, and the magnetized one for the magnetic field mapping. Our experiments show that the dual-tip technique minimizes the perturbations of the magnetic tip present in standard two-pass scanning.
- Tóbik, J., Cambel, V., Karapetrov, G.: Asymmetry in time evolution of magnetization in magnetic nanostructures. Sci Reports 5 (2015) 12301.
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Precner, M., Fedor, J., Šoltýs, J., Cambel, V.: Dual-tip magnetic force microscopy with suppressed influence on magnetically soft samples. Nanotechnol. 26 (2015) 055304.
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