Two-dimensional incommensurate magnetic fluctuations in Sr2_2(Ru0.99_{0.99}Ti0.01_{0.01})O4_4

We investigate the imaginary part of the wave vector dependent dynamic spin susceptibility in Sr$_2$(Ru$_{0.99}$Ti$_{0.01}$)O$_4$ as a function of temperature using neutron scattering. At T=5 K, two-dimensional incommensurate (IC) magnetic fluctuations are clearly observed around $\mathbf{Q}_\text{c}=(0.3,0.3,L)$ up to approximately 60 meV energy transfer. We find that the IC excitations disperse to ridges around the $(\pi,\pi)$ point. Below 50 K, the energy and temperature dependent excitations are well described by the phenomenological response function for a Fermi liquid system with a characteristic energy of 4.0(1) meV. Although the wave vector dependence of the IC magnetic fluctuations in Sr$_2$(Ru$_{0.99}$Ti$_{0.01}$)O$_4$ is similar to that in the Fermi liquid state of the parent compound, Sr$_2$RuO$_4$, the magnetic fluctuations are clearly suppressed by the Ti-doping.Comment: 5 pages, 4 figure

Glassy phonon heralds a strain glass state in a shape memory alloy

Shape memory strain glasses are frustrated ferroelastic materials with glasslike slow relaxation an

Detailed Structure of a CDW in a Quenched Random Field

Using high resolution x-ray scattering, we have measured the structure of the Q_1 CDW in Ta-doped NbSe_3. Detailed line shape analysis of the data demonstrates that two length scales are required to describe the phase-phase correlation function. Phase fluctuations with wavelengths less than a new length scale $a$ are suppressed and this $a$ is identified with the amplitude coherence length. We find that xi_a* = 34.4 \pm 10.3 angstroms. Implications for the physical mechanisms responsible for pinning are discussed.Comment: revtex 3.0, 3 postscript uuencoded figure

Lattice vibrations boost demagnetization entropy in a shape-memory alloy

Magnetocaloric (MC) materials present an avenue for chemical-free, solid state refrigeration through cooling via adiabatic demagnetization. We have used inelastic neutron scattering to measure the lattice dynamics in the MC material Ni45Co5Mn36.6In13.4. Upon heating across the Curie Temperature (TC), the material exhibits an anomalous increase in phonon entropy of 0.22 +/- 0.04 kB/atom, which is ten times larger than expected from conventional thermal expansion. This transition is accompanied by an abrupt softening of the transverse optic phonon. We present first-principle calculations showing a strong coupling between lattice distortions and magnetic excitations

Sensitivity Studies for Third-Generation Gravitational Wave Observatories

Advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. The Einstein Telescope, a third-generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. In this article we describe sensitivity models for the Einstein Telescope and investigate potential limits imposed by fundamental noise sources. A special focus is set on evaluating the frequency band below 10Hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. We develop the most accurate sensitivity model, referred to as ET-D, for a third-generation detector so far, including the most relevant fundamental noise contributions.Comment: 13 pages, 7 picture