It is well known phenomenon, that the average magnetic domain size or magnetic periodicity in the magnetic film with perpendicular magnetic anisotropy is less if the magnetic film is demagnetized by in-plane field than by out-of-plane field. In the first case, anisotropic stripe domain pattern developes. In the second case, isotropic maze structure is observed. Micromagnetic calculations indicate that total energy of the system in the aligned demagnetized state is less than in the maze state. But what is physical origin of such phenomenon? Is it related with the different energy, width or total perimeter of the domain walls? Does anybody know any books where can I find information about this question?
It is related to rather thick superlattices which self-demagnetize in the absence of perpendicular magnetic field. Out-of-plane hysteresis loop of such structures resebles well-known vortex loop and has 0 remanent magnetization. Interestingly that total energy of maze demagnetized state is less if compare to the total energy of ideally aligned state if the periodicity is the same and periodic boundary conditions are included.
Hello.
As you know, in the energy landscape there are several local minima, and the one that is reached by the sample depends on the magnetic history. What is the main difference between the two process: in-plane or out-of-plane demagnetization? The contribution of the Zeeman energy. When you apply an in-plane field, you are favoring the formation of Bloch-type domain walls: the spins at the center of the wall are aligned with the external magnetic field. However, when you apply out-of-plane field, you are not favoring the formation of domain walls, since the field is applied in the direction of the magnetocrystalline easy axis (i.e. in the preferred direction for the magnetization inside the domains).
The most complete book about this subject is “Magnetic Domains. The Analysis of Magnetic Microstructures” by Alex Hubert and Rudolf Schäfer.
Hello, Jose-Miguel,
I agree with you, the magnetic state depends on the magnetic history and previous magnetic treatment with the sample. A question that is needed to be solved for me is what state is equilibrium: demagnetized in-plane or out-of-plane? Occasionally all theoretical papers consider not labyrinth state but ideal stripe state (or bubble state in some cases) due to its simplicity. So the only way, as I understood, is using micromagnetic simulations.
Both states, the one reached by in-plane field and the one reached by perpendicular field, are stable, i.e. are equilibrium states, local minima in the energy landscape. If you want to know which one has the lowest energy, yes: you can perform micromagnetic simulations and compare the energies once the convergence criterion is obtained.
- Badges
- Science topic
- Similar topics
- Biological Science
- Physiology
- Physiological Processes
- Stress