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MA: Fachverband Magnetismus

MA 7: Poster Magnetism I

MA 7.86: Poster

Montag, 9. März 2026, 09:30–12:30, P2

Temperature dependence of the spin-wave dispersion in the spin-polarized homogeneous electron gas — •Michael Neugum, Noah Spiegelberg, and Arno Schindlmayr — Universität Paderborn, Department Physik, 33095 Paderborn, Germany

Spin waves are an important class of elementary excitations in magnetically ordered materials. Due to the absence of an energy gap, they are easily thermally excited and, consequently, influence technological applications like spintronics or magnetic data storage. The impact of temperature is twofold: First, the occupation numbers of the bosonic spin-wave modes increase with the temperature. Second, the dispersion itself changes, leading to lowered spin-wave energies and hence to an accelerated population. The latter effect is largely ignored in current ab initio calculations, which are typically performed at 0 K and often lack proper temperature-dependent functional expressions. Here we calculate the spin-wave dispersion of the spin-polarized homogeneous electron gas at finite temperature within time-dependent density-functional theory, taking only the exchange functional into account. The temperature dependence of the exchange kernel is fully included. Our results demonstrate that the spin-wave energies are indeed systematically lowered as the temperature increases. As an important observation, the spin-wave stiffness also decreases, so that there is a nonnegligible effect on long-wavelength modes and on thermodynamic quantities, such as the specific heat capacity, even at low temperature.

Keywords: spin waves; spin-polarized electron gas; time-dependent density-functional theory; temperature dependence