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arXiv · 1610.03334

Magnetodielectric detection of magnetic quadrupole order in Ba(TiO)Cu$_4$(PO$_4$)$_4$ with Cu$_4$O$_{12}$ square cupolas

K. Kimura·P. Babkevich·M. Sera·M. Toyoda·K. Yamauchi·G. S. Tucker·J. Martius·T. Fennell·P. Manuel·D. D. Khalyavin·R. D. Johnson·T. Nakano·Y. Nozue·H. M. Rønnow·T. Kimura
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Abstract

In vortex-like spin arrangements, multiple spins can combine into emergent multipole moments. Such multipole moments have broken space-inversion and time-reversal symmetries, and can therefore exhibit linear magnetoelectric (ME) activity. Three types of such multipole moments are known: toroidal, monopole, and quadrupole moments. So far, however, the ME-activity of these multipole moments has only been established experimentally for the toroidal moment. Here, we propose a magnetic square cupola cluster, in which four corner-sharing square-coordinated metal-ligand fragments form a noncoplanar buckled structure, as a promising structural unit that carries an ME-active multipole moment. We substantiate this idea by observing clear magnetodielectric signals associated with an antiferroic ME-active magnetic quadrupole order in the real material Ba(TiO)Cu$_4$(PO$_4$)$_4$. The present result serves as a useful guide for exploring and designing new ME-active materials based on vortex-like spin arrangements.

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K. Kimura, P. Babkevich, M. Sera, M. Toyoda, K. Yamauchi, G. S. Tucker, J. Martius, T. Fennell, P. Manuel, D. D. Khalyavin, R. D. Johnson, T. Nakano, Y. Nozue, H. M. Rønnow, T. Kimura. 2016-10-11. Magnetodielectric detection of magnetic quadrupole order in Ba(TiO)Cu$_4$(PO$_4$)$_4$ with Cu$_4$O$_{12}$ square cupolas. https://doi.org/10.1038/ncomms13039

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