Abstract
We present an investigation of the multiferroic lacunar spinel compound GeV4S8 using time-domain terahertz spectroscopy. We find three absorptions which either appear or shift at the antiferromagnetic transition temperature, TN=17K, as S=1 magnetic moments develop on vanadium tetrahedra. Two of these absorptions are coupled to the magnetic state and one only appears below the Néel temperature, and is interpreted as a magnon. We also observe isosbestic points in the dielectric constant in both the temperature and frequency domains. Further, we perform an analysis on the isosbestic features to reveal an interesting collapse into a single curve as a function of both frequency and temperature, behavior which exists throughout the phase transitions. This analysis suggests the importance of spectral changes in the terahertz range which are linear in frequency and temperature.
| Original language | English |
|---|---|
| Article number | 054432 |
| Journal | Physical Review B |
| Volume | 96 |
| Issue number | 5 |
| DOIs | |
| State | Published - Aug 23 2017 |
Funding
Work at OSU was supported by the NSF MRSEC Center for Emergent Materials under Grant No. DMR-1420451. G.P. and D.M. were supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant No. GBMF4416. Work at the Spallation Neutron Source was supported by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy. Evan Jasper, Shirley Li, and Thuc T. Mai are thanked for their assistance in this work.
| Funders | Funder number |
|---|---|
| NSF MRSEC Center for Emergent Materials | |
| Office of Basic Energy Sciences | |
| Scientific User Facilities Division | |
| U.S. Department of Energy | |
| Directorate for Mathematical and Physical Sciences | 1420451 |
| Gordon and Betty Moore Foundation |