High-Energy Magnetic Excitations in MnSb₂Te₄

MnSb2Te4 is emerging as a promising material platform that uniquely combines intrinsic magnetism with nontrivial band topology at record-high temperatures.
Our recent Xpress measurement on a 5 g MnSb2Te4 powder sample performed on MARI revealed magnetic excitations (possibly magnons) below 5 meV. At higher energies (around 150 meV), we observed a weak signal; however, due to instrumental limitations, it wasn't possible to have a clear observation of the high-energy modes. To probe these excitations more effectively, we propose using higher incident energies to access low-Q scattering, where the magnetic signal is expected to be strongest.
Further motivation for targeting this high energy range with INS comes from our latest ARPES measurements on MnSb2Te 4 (Tc = 32 K), which reveal a clear kink in the band structure when measured below the transition temperature. The large energy scale of this feature (~150 meV) and its disappearance above Tc represent smoking-gun evidence for possible electron magnon coupling.
We request an Xpress measurement at MAPS on a ~5 g powder sample of MnSb2Te4 , using incident energies in the range of ~ 0.5 - 1 eV, to specifically target the 120 - 180 meV region. The measurement will be performed at a base temperature of 6 K to probe the ordered magnetic phase. If sufficient beamtime allows, we would like also perform a complementary measurement above Tc 32 K (e.g., at 80 K) to distinguish magnetic from non-magnetic contributions.