Dresden 2017 – wissenschaftliches Programm
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DF: Fachverband Dielektrische Festkörper
DF 17: Ferroics - Domains, Domain Walls and Skyrmions IV
DF 17.2: Vortrag
Donnerstag, 23. März 2017, 10:00–10:15, WIL B321
Investigating the structural phase transition of GaV4S8 — •Jonathan Döring1, Ádám Butykai2, Istvan Kézsmárki2, Peter Milde1, Susanne C. Kehr1, and Lukas M. Eng1 — 1Technische Universität Dresden, Institut für Angewandte Physik — 2MTA-BME Lendület Magneto-optical Spectroscopy Research Group
GaV4S8 (GVS) is a lacunar spinel. As most materials of this group, it features several magnetic phases at low temperatures, most notably a skyrmion lattice (SkL) phase between 9 K and 13 K under low magnetic fields [1]. Upon cooling below T = 42 K, GVS exhibits a Jahn-Teller phase transition, changing the crystal structure from paraelectric cubic to ferroelectric rhombohedral. The multiferroic nature of the skyrmions offers interesting application perspectives in magnetoelectronics.
We study GVS by means of low-temperature piezoresponse force microscopy (LT-PFM) [2] and low-temperature scattering scanning near-field optical microscopy (LT-s-SNOM) [3] in order to characterize the ferroelectric domain configurations on the nanometer length scale. LT-PFM measurements are performed at temperatures both below and above the Jahn-Teller phase transition on as-grown (100) and (111) surfaces of single crystalline GVS. We observe several types of domain configurations in the rhombohedral phase. Applying LT-s-SNOM shows an enhanced response at wavelengths around λ = 31.5 µ m close to a GVS phonon mode, enabling IR-imaging of the crystal anisotropy.
[1] Kezsmarki, I. et al., Nature Materials 14, 1116-1122 (2015)
[2] Butykai, A. et al., submitted
[3] Döring, J. et al., Applied Physics Letters 105, 053109 (2014)