Spin waves can probe the Dzyaloshinskii-Moriya interaction (DMI), which gives rise to topological spin textures, such as skyrmions. However, the DMI has not yet been reported in yttrium iron garnet (YIG) with arguably the lowest damping for spin waves. In this work, we experimentally evidence the interfacial DMI in a 7-nm-thick YIG film by measuring the nonreciprocal spin-wave propagation in terms of frequency, amplitude, and most importantly group velocities using all electrical spin-wave spectroscopy. The velocities of propagating spin waves show chirality among three vectors, i.e., the film normal direction, applied field, and spin-wave wave vector. By measuring the asymmetric group velocities, we extract a DMI constant of $16\mu \mathrm{J}/{\mathrm{m}}^2$, which we independently confirm by Brillouin light scattering. Thickness-dependent measurements reveal that the DMI originates from the oxide interface between the YIG and garnet substrate. The interfacial DMI discovered in the ultrathin YIG films is of key importance for functional chiral magnonics as ultralow spin-wave damping can be achieved.

Strong coupling of electromagnetic cavity fields with antiferromagnetic spin waves in hematite ($\alpha$-${\mathrm{Fe}}_2{\mathrm{O}}_3$) is achieved above room temperature. A cube of hematite is placed in a metallic tube and the transmission is measured, using a continuous-wave terahertz spectrometer. The spectra, collected as a function of the temperature, reveal the formation of magnetic polaritons.

Hematite (α-Fe₂O₃) is an antiferromagnetic material with a very low spin damping and high Néel temperature. The temperature dependence of the antiferromagnetic resonance in a bulk single crystal of hematite was characterized from room temperature up to the Néel temperature in the frequency range of 0.19–0.5 THz. From these data, the Néel temperature was estimated as 966 K.

Iron garnets as an important type of low-damping magnetic insulator can provide an ideal platform for the field of magnonics. In this work, we study the propagation of spin waves in a 60 nm-thick TmIG film with perpendicular magnetic anisotropy using all-electrical spin wave spectroscopy. The magnetostatic forward volume mode spin waves show a fully reciprocal propagation. By sweeping out-of-plane magnetic fields in the low-field regime, spin textures are created and observed; meanwhile, the spin wave mode vanishes, which indicates that propagating spin waves are filtered by the spin textures. By applying a large in-plane field, spin wave propagation in a Damon–Eshbach configuration is studied. Our findings provide a potential method to explore reconfigurable magnonic devices.

Spin wave propagation in perovskite La_0.33 Sr_0.67 MnO₃ films epitaxially grown on a SrTiO₃ substrate of (001) orientation was investigated using an all electrical spin wave spectroscopy technique. The spin wave nonreciprocity in amplitude, resonance frequency, and group velocity of the transmission spectra were observed. The origin of the spin-wave nonreciprocity is attributed to the out-of-plane surface anisotropy, with a value of 1.3 mJ/m² at the interface with the substrate, as extracted from the theoretical model. The magnetic field dependence of the frequency shift is attributed to the perpendicular surface anisotropy. The important role of the surface anisotropy in the spin wave nonreciprocity was further confirmed by the angle dependent measurements of the spin wave transmission spectra.