Abstract-Role of commensurability of spin order for optical magnetoelectric effect with electromagnons in multiferroic YMn2O5

R. Masuda, Y. Kaneko, Y. Yamasaki, Y. Tokura, and Y. Takahashi

https://journals.aps.org/prb/accepted/8e071Y8bOb21675532797ee972b87bc76cc0a7fb6


Optical magnetoelectric effect, which produces the nonreciprocal directional dichroism, on the electromagnon resonances is investigated for multiferroic phases of YMn2O5 by terahertz spectroscopy. For the electromagnon driven by the exchange striction, a crucial role of the commensurability of spin order in the magnetoelectric coupling is manifested by the suppression of the directional dichroism in the incommensurate spin phase. Furthermore, the gapped electromagnon via the spin-current mechanism is identified in term of the directional dichroism, being irrespective of commensurability/incommensurability in the cycloidal spin order.