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Multiferroic materials have been intensively studied these last decades for their interesting physics and their promising magnetoelectric applications [1]. Materials having a crystallographic chirality are particularly interesting in the sense that their structure can couple to magnetism an display novel magnetoelectric coupling mechanisms. This is the case of MnSb$_2$O$_6$ which crystallizes in the noncentrosymmetric $P$321 space-group. The Mn$^{2+}$ magnetic ions are arranged in a triangular motif in the $(ab)$-plane, where the magnetic moments are dephased by 120° and follow a cycloidal modulation along the $c$-axis [2]. The respective sense of rotation of the spins, the so-called magnetic chiralities are directly linked through Heisenberg interactions to the structural chirality, defined as the helical winding of super-super-exchange pathways along the c-axis. This compound was predicted to have a unique ferroelectric switching mechanism, but the magnetic ground state remained ambiguous [2,3]. By a combination of unpolarized and polarized neutron diffraction techniques, we have extensively studied both the nuclear and magnetic structures of MnSb$_2$O$_6$. We have notably used polarized neutrons to perform Schwinger scattering, sensitive to structural chirality, and spherical neutron polarimetry, sensitive to magnetic chirality, and found out a complex mixture of chiral structural and magnetic domains. We subsequently propose a mechanism leading to electric polarization based on coupled structural and magnetic chiralities [4].
[1] S. W. Cheong et al. Nature Mater 6, 13 (2007)
[2] R. D. Johnson et al. Phys. Rev. Lett. 111, 017202 (2013)
[3] M. Kinoshita et al. Phys. Rev. Lett. 117, 047201 (2016)
[4] E. Chan et al. Phys. Rev. B 106, 064403 (2022)
