arXiv subjects

P. Link

Publications and source records attributed to P. Link.

21 records · Page 2Linked to original sources

arXiv2006

Magnetic excitations in multiferroic TbMnO3

The magnetic excitations in multiferroic TbMnO3 have been studied by inelastic neutron scattering in the spiral and sinusoidally ordered phases. At the incommensurate magnetic zone center of the spiral phase, we find three low-lying magnons whose character has been fully determined using neutron-polarization analysis. The excitation at the lowest energy is the sliding mode of the spiral, and two modes at 1.1 and 2.5meV correspond to rotations of the spiral rotation plane. These latter modes are expected to couple to the electric polarization. The 2.5meV-mode is in perfect agreement with recent infra-red-spectroscopy data giving strong support to its interpretation as an hybridized phonon-magnon excitation.

cond-mat.str-el↗

arXiv2001

Antiferroquadrupolar Order in the Magnetic Semiconductor TmTe

The physical properties of the antiferroquadrupolar state occurring in TmTe below TQ=1.8 K have been studied using neutron diffraction in applied magnetic fields. A field-induced antiferromagnetic component k = (1/2,1/2,1/2) is observed and, from its magnitude and direction for different orientations of H, an O(2,2) quadrupole order parameter is inferred. Measurements below TN ~= 0.5 K reveal that the magnetic structure is canted, in agreement with theoretical predictions for in-plane antiferromagnetism. Complex domain repopulation effects occur when the field is increased in the ordered phases, with discontinuities in the superstructure peak intensities above 4 T.

cond-mat.str-el↗

arXiv1997

Ferromagnetic Mixed-Valence and Kondo-Lattice State in TmTe at High Pressure

Neutron diffraction experiments on TmTe at pressures up to 7 GPa are reported. The semiconductor-to-metal transition occurring at 2 GPa in this compound is accompanied by the appearance of strong ferromagnetic exchange interactions producing a Curie temperature as high as 14 K. This behavior is characteristic for the incipient mixed-valence regime just above the transition pressure and traced back to the release of a small concentration of free charge carriers in the material. The steep decrease of both the Curie temperature and ordered magnetic moment occurring at higher pressures emphasizes the role of Kondo fluctuations, and raises the interesting possibility that a quantum critical transition to a non-magnetic ground state of mixed-valence Tm might take place around 6 GPa.

cond-mat.str-el↗