Luis M. Moreno-Ramírez

arXiv2026

Reflection of forward volume exchange spin waves at ferromagnetic junctions interpreted via continuity of angular momentum density flux

Magnonics investigates the dynamic excitations of magnetically ordered media, known as spin waves, and their application in functionalized devices. To efficiently control spin wave based devices minimizing losses and interferences from unwanted reflections, a clear picture of the scattering mechanism is needed. Here, we focus on the reflection of spin waves produced at the interface between two ferromagnetic media. We show that it is possible to understand the reflection mechanism based on the continuity of the angular momentum density flux. This constraint allows us to analytically compute the reflection coefficient and the stationary wave envelope in the first medium, as well as the damped propagation in the second. In addition, the analytical expressions are compared with full micromagnetic simulations, showing excellent agreement.

cond-mat.mtrl-sci↗

arXiv2025

Landau-Lifshitz-Bloch simulations of the magnetocaloric effect in continuous ferromagnetic-paramagnetic transitions

The usefulness of modeling magnetocaloric materials expands from the understanding of their behavior to the prediction of new materials, playing a fundamental role in the optimization of their performance. In contrast with other areas of magnetic materials research, micromagnetic simulations of magnetocaloric materials are scarce due to the difficulty of modeling the material in the vicinity of the transition. To solve this limitation, we propose the use of micromagnetic simulations based on the Landau-Lifshitz-Bloch equation to study the magnetocaloric effect of a ferromagnetic material around its Curie transition. Following our proposed methodology, we obtain reliable isothermal entropy change curves for both monocrystalline and polycrystalline configurations, where we consider different anisotropic contributions. The robustness of the method was evaluated, yielding results that agreed with previous experimental and theoretical observations. Our study shows that micromagnetic simulations are a powerful tool for analyzing magnetocaloric materials with complex microstructures.

cond-mat.mtrl-sci↗