N. Mufti

Large coupled magnetoresponses in EuNbO2N

We have explored a new strategy to discover materials with large resistive or capacitive responses to magnetic fields by synthesizing EuMO2N (M = Nb, Ta) perovskites that combine ferromagnetic order of S = 7/2 Eu2+ spins with possible off-center distortions of the d0 M5+ cations enhanced by covalent bonding to N. EuNbO2N shows colossal magnetoresistances at low temperatures and a giant magnetocapacitance. However, the latter response originates from a microstructural effect rather than an intrinsic multiferroism.

Orbital superexchange and crystal field simultaneously at play in YVO3: resonant inelastic x-ray scattering at the V L edge and the O K edge

We report on the observation of orbital excitations in YVO3 by means of resonant inelastic x-ray scattering (RIXS) at energies across the vanadium L-3 and oxygen K absorption edges. At the V L3 edge, we are able to resolve the full spectrum of orbital excitations up to 5 eV. In order to unravel the effect of superexchange interactions and the crystal field on the orbital excitations, we analyzed the energy and temperature dependence of the intra-t(2g) excitations at 0.1-0.2 eV in detail. While these results suggest a dominant influence of the crystal field, peak shifts of about 13-20 meV observed as a function of the transferred momentum q parallel to a reflect a finite dispersion of the orbital excitations. This is puzzling since theoretical models based on superexchange interactions predict a dispersion only for q parallel to c. Furthermore, we demonstrate that RIXS at the O K edge is very sensitive to intersite excitations. At the O K edge, we observe excitations across the Mott-Hubbard gap and an additional feature at 0.4 eV, which we attribute to two-orbiton scattering, i.e., an exchange of orbitals between adjacent sites. Altogether, our results indicate that both superexchange interactions and the crystal field are important for a quantitative understanding of the orbital excitations in YVO3.

Dynamics of photo-excited electrons in magnetically ordered TbMnO3

Time resolved optical spectroscopy is used to elucidate the dynamics of photodoped spin-aligned carriers in the presence of an underlying magnetic lattice in the multiferroic compound TbMnO(3). The transient responses while probing d-d intersite transitions show marked differences along different crystallographic directions, which are discussed in terms of the interplay between the processes of hopping of the photo-injected electrons and the magnetic order in the material.

Unique magnetic structure of YbCo2Si2

We report on the results of powder and single crystal neutron diffraction to investigate the magnetic order in YbCo

Magnetic transitions in YbCo2Si2

_2

Magnetodielectric coupling in frustrated spin systems: the spinels MCr2O4 (M = Mn, Co and Ni)

Si

Magnetoelectric coupling in MnTiO3

_2

Relaxor ferroelectric behavior in Ca-doped TbMnO3

below the Neel temperature

Aurivillius phases of PbBi4Ti4O15 doped with Mn3+ synthesized by molten salt technique: Structure, dielectric, and magnetic properties

T_{\rm N} = 1.7~

Aurivillius phases of PbBi{sub 4}Ti{sub 4}O{sub 15} doped with Mn{sup 3+} synthesized by molten salt technique: Structure, dielectric, and magnetic properties

K in detail. Two different magnetically ordered phases can clearly be distinguished. At lowest temperatures a commensurate magnetic structure with a propagation vector