Magnetic behavior of NaMnSb

Room temperature antiferromagnetic (AFM) semiconductors are considered feasible alternatives to ferromagnetic (FM) electrodes in magnetic random-access memories. The stability of AFMs under external magnetic fields and their absence of stray magnetic fields make them suitable for optoelectronic and transistor applications, and AFM spin valves, in contrast to conventional ferromagnets such as Ni, Co, and Fe. I-Mn-V systems have been identified as a promising AFM spintronic candidate, exhibiting Néel temperatures (T_N) above 300 K. NaMnSb is a Heusler class I–Mn–V compound that remains largely unexplored. It has a tetragonal crystal structure (P4/nmm) which consists of layers of tetrahedral Mn coordinated with Sb and Na intercalation in between the layers. The inelastic neutron scattering results obtained from constant E-scans at ℏω = 2 meV, 5 meV, and 8 meV along (H00), at 300 K and 500 K clearly exhibit dispersion peaks. Constant Q-scan across (100) as a function of temperature suggests a possible anisotropy gap at low temperatures. Furthermore, linear spin wave calculations using a Heisenberg Hamiltonian were applied, and the three exchange constants were determined to be J₁ = 9.916, J₂ = 3.352, and J_c = -0.236, where J₁ and J₂ represent the intraplanar nearest neighbor interactions, while J_c denotes the interplanar nearest neighbor interaction. The calculated dispersion successfully reproduces a curve consistent with the three experimental data points.