Investigation of the complex chiral spin structures of the kagome magnet TmMn6Sn6

The understanding and subsequent control of novel magnetic textures are crucial for the development of new quantum materials for spin-based electronic devices. Materials that are responsive to perturbations such as magnetic fields and temperatures are key to the discovery of these novel magnetic states and phenomena. One such class of materials are the kagome magnets. Complex physics has been shown to arise from the noncollinear interplanar ordering between FM kagome planes, such as topological Hall effect in the absence of crystallographic inversion symmetry breaking. In contrast to AF kagome materials, the in-plane exchange interaction in these FM kagome planes adopts characteristics of kagome geometry such as Dirac cones and flat bands. The 166 family have been shown to demonstrate these interesting phenomena. A recent study of YMn6Sn6 identified several nontrivial magnetic phases, driven by magnetic fluctuations from the frustrated interplanar exchange interactions, of which one of the resulting phases hosts a topological Hall effect. A powder neutron diffraction study on TmMn6Sn6 and its doped variants revealed the appearance of non-trivial magnetic states with temperature. Our single crystal samples provide ample opportunity to investigate the proposed triple spiral structure and non-trivial magnetic phases. Further investigation of the phase transitions will shed light on the nature of the phase diagram and its directional anisotropy, as well as the effect of doping.