786 research outputs found
Bone mineralization in European eel (Anguilla anguilla) during maturation from the yellow eel stage to the silver eel stage
Inversion symmetry in the spin-Peierls compound NaV2O5
At room-temperature NaV2O5 was found to have the centrosymmetric space group
Pmmn. This space group implies the presence of only one kind of V site in
contrast with previous reports of the non-centrosymmetric counterpart P21mn.
This indicates a non-integer valence state of vanadium.
Furthermore, this symmetry has consequences for the interpretation of the
transition at 34 K, which was ascribed to a spin-Peierls transition of one
dimensional chains of V4+.Comment: Revtex, 3 pages, 2 postscript pictures embedded in the text.
Corrected a mistake in one pictur
Dynamics of spin and orbital phase transitions in YVO3
YVO3 exhibits a well separated sequence of orbital and spin order transitions
at 200 K and 116 K, followed by a combined spin-orbital reorientation at 77 K.
It is shown that the spin order can be destroyed by a sufficiently strong
optical pulse within less than 4 ps. In contrast, the orbital reordering
transition from C-type to G-type orbital order is slower than 100 ps and goes
via an intermediate nonthermal phase. We propose that the dynamics of phase
transitions is subjected to symmetry relations between the associated phases.Comment: 5 pages, 3 figure
Evidence for differentiation in the iron-helicoidal-chain in GdFe(BO)
We report on a single-crystal X-ray structure study of
at room temperature and at T=90 K. At room temperature
crystallizes in a trigonal space group R32 (No. 155), the same as found for
other members of iron-borate family . At 90 K the
structure of has transformed to the space group
(No. 152). The low-temperature structure determination gives new
insight into the weakly first-order structural phase transition at 156 K and
into the related Raman phonon anomalies. The discovery of two inequivalent iron
chains in the low temperature structure provide new point of view on the
low-temperature magnetic properties.Comment: Subm. to Acta Cryst.
Angular Dependence of the High-Magnetic-Field Phase Diagram of URu2Si2
We present measurements of the magnetoresistivity RHOxx of URu2Si2 single
crystals in high magnetic fields up to 60 T and at temperatures from 1.4 K to
40 K. Different orientations of the magnetic field have been investigated
permitting to follow the dependence on Q of all magnetic phase transitions and
crossovers, where Q is the angle between the magnetic field and the easy-axis
c. We find out that all magnetic transitions and crossovers follow a simple
1/cos(Q) -law, indicating that they are controlled by the projection of the
field on the c-axis
Ferroelectric displacements in multiferroic Y(Mn,Ga)O-3
We have studied the effects of substitution of Mn3+ by Ga3+ on the crystal structure of YMnO3. Y(Mn,Ga)O-3 is a magnetoferroelectric in which the ferroelectric displacements from the YO7 polyhedra are associated with buckling and tilting of the MnO5 bipyramids. The differences in ionic radius and orbital occupation between Mn3+ and Ga3+ result in an increase of the c/a lattice parameter ratio. This dilation is not associated with the displacements of MnO5 bipyramids, but with the elongation of the YO6 antiprisms. The magnitude of the local YO6 dipoles decrease with Ga substitution
11 King's Quay Street/11 St Austin's Lane, harwich, Essex: tree-ring analysis and radiocarbon wiggle-matching of elm and oak timbers
Spin-Hall magnetoresistance and spin Seebeck effect in spin-spiral and paramagnetic phases of multiferroic CoCr2O4 films
We report on the spin-Hall magnetoresistance (SMR) and spin Seebeck effect
(SSE) in multiferroic CoCr2O4 (CCO) spinel thin films with Pt contacts. We
observe a large enhancement of both signals below the spin-spiral (Ts = 28 K)
and the spin lock-in transitions (T_{lock_in} = 14 K). The SMR and SSE response
in the spin lock-in phase are one order of magnitude larger than those observed
at the ferrimagnetic transition temperature (Tc = 94 K), which indicates that
the interaction between spins at the Pt|CCO interface is more efficient in the
non-collinear magnetic state below Ts and T_{lock-in}. At T > Tc, magnetic
field-induced SMR and SSE signals are observed, which can be explained by a
high interface susceptibility. Our results show that the spin transport at the
Pt|CCO interface is sensitive to the magnetic phases but cannot be explained
solely by the bulk magnetization
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