Research: Characteristics of ferroelectric / ferroelastic domains in Néel-type skyrmion host GaV4S8

Materials that possess both magnetic and dielectric polarization with mutual interactions are of central interest. Here, we introduce into GaV₄S₈ (GVS), a multiferroic semiconductor, that hosts Néel-type magnetic skyrmions (see Fig. 1a),1b) dressed with electric polarization (Fig. 1c),1d). Below 42 K, the GVS compound undergoes a structural phase transition into a polar rhombohedral structure, splitting up into ferroelectric domains (Fig. 1c) that we investigated on the nm length scale using dedicated low-temperature scanning probe techniques. The electrical polarization always points along one of the four 〈111〉 directions within the lacunar spinel unit cell parallel to the Jahn-Teller distortion and the easy axis anisotropy, which pins the magnetic Néel-type skyrmions (Fig. 1a). Moreover, the dielectric polarization aligns in lamellae along the (100) planes (Fig. 1d), showing a typical spacing of ~100 nm to 1.2 µm, that gives rise to ferroelectric and ferroelastic domain walls. It is these domain walls that most probably limit the skyrmions correlation length in this GVS material.

Á. Butykai, S. Bordács, I. Kézsmárki, V. Tsurkan, A. Loidl, J. Döring, P. Milde, S. C. Kehr, L. M. Eng,
Characteristics of ferroelectric-ferroelastic domains in Néel-type skyrmion host GaV₄S_8,
Sci. Rep. 7, 44663 (2017) (arXiv)