42 research outputs found
Optical conductivity in multiferroic GaVS and GeVS: Phonons and electronic transitions
We report on optical spectroscopy on the lacunar spinels GaVS and
GeVS in the spectral range from 100 to 23000 cm and for
temperatures from 5 to 300 K. These multiferroic spinel systems reveal
Jahn-Teller driven ferroelectricity and complex magnetic order at low
temperatures. We study the infrared-active phonon modes and the low-lying
electronic excitations in the cubic high-temperature phase, as well as in the
orbitally and in the magnetically ordered low-temperature phases. We compare
the phonon modes in these two compounds, which undergo different
symmetry-lowering Jahn-Teller transitions into ferroelectric and orbitally
ordered phases, and exhibit different magnetic ground states. We follow the
splitting of the phonon modes at the structural phase transition and detect
additional splittings at the onset of antiferromagnetic order in GeVS.
We observe electronic transitions within the -derived bands of the V
clusters and document a significant influence of the structural and magnetic
phase transitions on the narrow electronic band gaps.Comment: 12 pages, 10 figure
Spin excitations in the skymion host Cu2OSeO3
We have used inelastic neutron scattering to measure the magnetic excitation
spectrum along the high-symmetry directions of the first Brillouin zone of the
magnetic skyrmion hosting compound CuOSeO. The majority of our
scattering data are consistent with the expectations of a recently proposed
model for the magnetic excitations in CuOSeO, and we report best-fit
parameters for the dominant exchange interactions. Important differences exist,
however, between our experimental findings and the model expectations. These
include the identification of two energy scales that likely arise due to
neglected anisotropic interactions. This feature of our work suggests that
anisotropy should be considered in future theoretical work aimed at the full
microscopic understanding of the emergence of the skyrmion state in this
material.Comment: 5 pages, 6 figure
Spin-stretching modes in anisotropic magnets: spin-wave excitations in the multiferroic Ba2CoGe2O7
We studied spin excitations of the multiferroic Ba2CoGe2O7 in high magnetic
fields up to 33 T. In the electron spin resonance and far infrared absorption
spectra we found several spin excitations beyond the two conventional magnon
modes expected for such a two-sublattice antiferromagnet. We show that a
multi-boson spin-wave theory can capture these unconventional modes, that
include spin-stretching modes associated with an oscillating magnetic dipole
(or only quadrupole) moment. The lack of the inversion symmetry allows these
modes to become electric dipole active. We expect that the spin-stretching
modes can be generally observed in inelastic neutron scattering and light
absorption experiments in a broad class of ordered S > 1/2 spin systems with
strong single-ion anisotropy and/or non-centrosymmetric lattice structure.Comment: 5+4 pages, 3 figures, supplement added, manuscript revise
Terahertz spectroscopy of spin excitations in magnetoelectric LiFePO4 in high magnetic fields
Contains fulltext :
283891.pdf (Publisher’s version ) (Open Access
Spin excitations of magnetoelectric LiNiPO4 in multiple magnetic phases
Item does not contain fulltex
Reducing Remanufacturing Uncertainties with the Digital Product Passport
In contrast to the linear production model, the circular economy aims to close the loop of materials. One part of this approach is remanufacturing, which extends the lifetime of products. Various stakeholders in the supply chain are involved in remanufacturing. This makes the management and optimization of remanufacturing activities complex. The data required for optimization is often missing, which leads to uncertainties. A new European Commission initiative, the digital product passport (DPP), is believed to facilitate information exchange in the supply chain and cloud be a good solution to reduce uncertainties. The primary purpose of this paper is the quantification and evaluation of the advantages of the DPP. Based on real industrial data, a discrete event simulation model of a remanufacturing system with three production lines was developed. The authors suppose the hypothetical existence of a DPP and illustrate the benefits arising from its application