Abstract
The tunability of Dirac semimetals with antiferromagnetic Mn layers is of great interest. The observed sign change of interlayer magnetic coupling between CaMnBi2 and SrMnBi2 suggests ionic substitution as a potential tuning mechanism. If so, novel behavior near the compensation point could be expected. To explore this, we study a mixed-cation analog, Ca0.6Sr0.4MnSb2, where Bi is replaced by Sb. Conventional inelastic neutron scattering is impractical due to the small crystal size (m≈0.28 g) available for compositional studies; however, we find that using a neutron diffractometer with a wide-angle area detector we can obtain a good quality spin-wave signal, which is shaped by energy-momentum conservation and retains spectroscopic information even without direct energy analysis. Spin-wave modeling reveals an interlayer coupling quantitatively similar to SrMnSb2, indicating it is not directly tuned by ionic size and that the sign change in Bi-based compounds likely arises from the observed change in lattice symmetry. Beyond this key insight, our results present an efficient method for parametric and compositional studies of spin dynamics in small crystals.
| Original language | English |
|---|---|
| Article number | 116504 |
| Journal | Physical Review Letters |
| Volume | 134 |
| Issue number | 11 |
| DOIs | |
| State | Published - Mar 21 2025 |
Funding
We would like to thank Dr. J. Fernandez-Baca for pointing out earlier references to the diffraction method. This work at Brookhaven National Laboratory was supported by Office of Basic Energy Sciences (BES), Division of Materials Sciences and Engineering, U.S. Department of Energy (DOE), under Contract No. DE-SC0012704. This research used resources at the High Flux Isotope Reactor, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.