Abstract
Here, we present a detailed theoretical and experimental study on the pressure induced switching of anomalous Hall effect (AHE) in the triangular antiferromagnetic (AFM) compound Mn$_3$Sn. 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 inter-plane exchange parameters in the system. We experimentally demonstrate that the AHE in Mn$_3$Sn reduces from 5$\mu\Omega$ 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 Mn$_3$Sn systematically transforms into the helical AFM phase where the symmetry does not support a non-vanishing Berry curvature required for the realization of a finite AHE. The pressure dependent x-ray diffraction (XRD) 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 towards understanding the stabilization mechanism of different magnetic ground states in Mn$_3$Sn and related materials for their potential applications pertaining to AHE switching.
Highlights
Effective manipulation of magnetic structure can decisively control the electrical [1,2,3,4,5], thermal [6], and optical [7,8,9] properties in magnetic materials
To understand the origin of the helically modulated magnetic ground state, we first analyze the role of different exchange parameters within the classical Heisenberg model, H = i> j Ji jni · nj, where the exchange constants Ji j determine the strength and nature of interactions between Mn moments pointing along the unit vector n
We have successfully demonstrated the switching of anomalous Hall effect in antiferromagnetic Mn3Sn using hydrostatic pressure
Summary
Effective manipulation of magnetic structure can decisively control the electrical [1,2,3,4,5], thermal [6], and optical [7,8,9] properties in magnetic materials. In the case of electrical transport in a magnetic system, the spins of the conduction electrons exhibit a strong Hund’s coupling with the underlying magnetic structure. The fictitious magnetic field arising from such an interaction can significantly modify the path of the conduction electrons, leading to the observation of the anomalous Hall effect (AHE) and topological Hall effect (THE) in ferromagnets [1] and antiferromagnets [3,4,10]. The AHE in ferromagnets has a great potential for its utilization as a memory element in spintronic devices, the only viable mechanism seems to be the reversal of the underlying magnetic structure. In this regard, antiferromagnets with diverse magnetic structures are excellent candidates
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