In this work we studied magnetically ordered states and accompanying structural changes in the multiferroic FeTe2O5Br. Employing a combination of neutron diffraction and nuclear quadrupolar resonance (NQR) we managed to determine the incommensurate magnetic ordering in the paraelectric state (HT-IC), which exists in a narrow temperature range – just a few Kelvins before the multiferroic state (LT-IC) with finite electric polarization. In addition, we confirmed that electric polarization stems from magneto striction of Fe-O-Te-O-Fe exchange pathways, which is related to the phase shifts of the neighboring magnetic modulation waves.
COBISS.SI-ID: 26662439
In this work we studied magnetic, structural and dielectric properties of the FeTe2O5Cl compound. We have discovered that its ground state is multiferroic and that the corresponding magnetic ordering is very similar to the one in the isostructural FeTe2O5Br system. We also learned that the main difference between the two isostructural compounds is in the structural effects, accompanying the establishment of the multiferroic phase, which are in FeTe2O5Cl much more pronounced. Moreover, we assigned these structural changes to the shift of the O1 ion and correlate them with the polarization of the Te4+ lone-pair electrons. This way we confirmed that lone-pair electrons are indeed the carriers of the electric polarization in these systems.
COBISS.SI-ID: 27342375
In this work we determined the magnetic structure in the ground state of the spin-chain system CuSe2O5. This is characterized by staggered moments with significantly reduced size, as a consequence of quantum fluctuations. By employing various complementary experimental techniques we also determined the magnetic anisotropy of the system, which is responsible for the staggering of the moment as well as for a relatively small critical field leading to a spin-flop magnetic transition.
COBISS.SI-ID: 26630695