Pressure controlled trimerization for switching of anomalous Hall effect in triangular antiferromagnet Mn3Sn

Abstract

Here, we present a detailed theoretical and experimental study on the pressure induced switching of the anomalous Hall effect (AHE) in the triangular antiferromagnetic (AFM) compound Mn3Sn. Our theoretical model suggests pressure driven significant splitting of the in-plane Mn bond lengths, i.e., an effective trimerization, which in turn stabilizes a helical AFM ground state by modifying the interplane exchange parameters in the system. We experimentally demonstrate that the AHE in Mn3Sn reduces from 5µ? cm at ambient pressure to zero at an applied pressure of about 1.5 GPa. Furthermore, our pressure dependent magnetization study reveals that the conventional triangular AFM ground state of Mn3Sn systematically transforms into the helical AFM phase where the symmetry does not support a nonvanishing Berry curvature required for the realization of a finite AHE. The pressure dependent x-ray diffraction study rules out any role of structural phase transition in the observed phenomenon. In addition, the temperature dependent in-plane lattice parameter at ambient pressure is found to deviate from the monotonic behavior when the system enters into the helical AFM phase, thereby supporting the proposed impact of trimerization in controlling the AHE. We believe that the present study makes an important contribution toward understanding the stabilization mechanism of different magnetic ground states in Mn3Sn and related materials for their potential applications pertaining to AHE switching.