Using high-resolution x-ray scattering, we have demonstrated the existence of quenched disordered charge stripes in a single crystal of La (5/3)Sr (1/3)NiO (4) at low temperatures. Above the second-order transition critical scattering was observed due to fluctuations into the charge stripe phase. The charge stripes are shown to be two dimensional in nature both by measurements of their correlation lengths (xi(a) approximately 185 A, xi(b) = 400 A, and xi(c) approximately 25 A) and by the critical exponents of the charge strip transition. The charge stripe ordering did not develop long-range order even at low temperatures, indicating that the charge stripes are disordered and that the length scale of the disorder is quenched.

Using x-ray scattering we have measured the response of the incommensurate charge-density wave (CDW) modulation in the quasi-low-dimensional material 2H-NbSe2 to applied magnetic fields at low temperatures. The application of a magnetic field, either perpendicular or parallel to the layers of a single crystal of 2H-NbSe2, caused no significant change to either the correlation length or the intensity of the CDW satellites for magnetic fields up to 10 T. These results suggest that the enhancement of the resistance observed in low-dimensional CDW materials exposed to the applied magnetic field does not result from an appreciable conversion of carriers from the normal state to the CDW state. In addition 2H-NbSe2 is a superconductor at low temperatures (Tc = 7.2 K), whilst still within the incommensurate CDW state. This material therefore affords an opportunity to study any interaction between the CDW and superconducting condensates. High magnetic fields can suppress the superconducting state yet no change in the incommensurate CDW satellite correlation length or intensity was observed at high applied magnetic fields. These results conflict with spectroscopic measurements, which suggest a coupling between the superconducting gap excitations and the CDW.

Using magnetization, dielectric constant, and neutron diffraction measurements on a high quality single crystal of YBaCuFeO (YBCFO), we demonstrate that the crystal shows two antiferromagnetic transitions at [Formula: see text] K and [Formula: see text] K, and displays a giant dielectric constant with a characteristic of the dielectric relaxation at T . It does not show the evidence of the electric polarization for the crystal used for this study. The transition at T corresponds with a paramagnetic to antiferromagnetic transition with a magnetic propagation vector doubling the unit cell along three crystallographic axes. Upon cooling, at T , the commensurate spin ordering transforms to a spiral magnetic structure with a propagation vector of ([Formula: see text] [Formula: see text] [Formula: see text]), where [Formula: see text], [Formula: see text], and [Formula: see text] are odd, and the incommensurability δ is temperature dependent. Around the transition boundary at T, both commensurate and incommensurate spin ordering coexist.

Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. We have employed resonant x-ray magnetic scattering to specifically probe the magnetic order of the rare-earth ions in multiferroic TbMn 2 O 5 . Two energy resonances were observed, one originated from the E1-E1 dipolar transition and the other from the E2-E2 quadrupolar transition. These resonances directly probe the valence 5d band and the partially occupied 4f band, respectively. First, full polarization analysis, which is a measurement of the scattered polarization as a function of incident polarization, confirmed a spin polarization of the terbium valence states ͑probed by the E1-E1 transition͒ by the Mn 4+ spin density in the commensurate phase. Second, full polarization analysis data were collected in the low-temperature incommensurate and commensurate phases when tuned to the E2-E2 resonance. By employing a least-squares fitting procedure, the spin orientations of the terbium ion sublattice were refined.

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