Terahertz Vibrational Dynamics and DFT Calculations for the Quantum Spin Chain Linarite, PbCuSO(OH).

The low-dimensional quantum-magnet, linarite, PbCuS(OH), has been investigated using terahertz (THz) spectroscopy coupled with detailed density functional theory (DFT) calculations in order to explore the effects of the temperature on its lattice vibrations. Linarite is characterized by largely isolated CuO chains propagating along the crystallographic -axis, which at very low temperatures are responsible for exotic, quasi-1D magnetism in this material. To better understand the synergy between the structural bonds and lattice oscillations that contribute to these chains, polarized THz spectroscopic measurements were performed.

Spin Reorientation Transition and Negative Magnetoresistance in Ferromagnetic NdCrSb Single Crystals.

High-quality NdCrSb single crystals are grown using a Sn-flux method, for electronic transport and magnetic structure study. Ferromagnetic ordering of the Nd and Cr magnetic sublattices are observed at different temperatures and along different crystallographic axes. Due to the Dzyaloshinskii-Moriya interaction between the two magnetic sublattices, the Cr moments rotate from the axis to the axis upon cooling, resulting in a spin reorientation (SR) transition.

Anomalous Structural Evolution and Glassy Lattice in Mixed-Halide Hybrid Perovskites.

Hybrid halide perovskites have emerged as highly promising photovoltaic materials because of their exceptional optoelectronic properties, which are often optimized via compositional engineering like mixing halides. It is well established that hybrid perovskites undergo a series of structural phase transitions as temperature varies. In this work, the authors find that phase transitions are substantially suppressed in mixed-halide hybrid perovskite single crystals of MAPbI Br (MA = CH NH and x = 1 or 2) using a complementary suite of diffraction and spectroscopic techniques.

Data-processing technique for the Taipan "Be-filter" neutron spectrometer at the Australian Nuclear Science and Technology Organisation.

There are five filter-analyzer neutron spectrometers available worldwide for scientists to use in order to measure the vibrational density of states in various samples. While Taipan, the thermal spectrometer, has been operated as a triple-axis spectrometer at the Australian Centre for Neutron Scattering since 2010, a beryllium filter analyzer spectrometer was added in 2016. Due to the complex nature of the data post-processing, it has thus far been impossible to fully treat experimental data from scientific measurements taken over the last five years.

Spin texture induced by non-magnetic doping and spin dynamics in 2D triangular lattice antiferromagnet h-Y(Mn,Al)O.

Novel effects induced by nonmagnetic impurities in frustrated magnets and quantum spin liquid represent a highly nontrivial and interesting problem. A theoretical proposal of extended modulated spin structures induced by doping of such magnets, distinct from the well-known skyrmions has attracted significant interest. Here, we demonstrate that nonmagnetic impurities can produce such extended spin structures in h-YMnO, a triangular antiferromagnet with noncollinear magnetic order.

First extensive study of silver-doped lanthanum manganite nanoparticles for inducing selective chemotherapy and radio-toxicity enhancement.

Nanoparticles have a great potential to increase the therapeutic efficiency of several cancer therapies. This research examines the potential for silver-doped lanthanum manganite nanoparticles to enhance radiation therapy to target radioresistant brain cancer cells, and their potential in combinational therapy with magnetic hyperthermia. Magnetic and structural characterisation found all dopings of nanoparticles (NPs) to be pure and single phase with an average crystallite size of approximately 15 nm for undoped NPs and 20 nm for silver doped NPs.

Order, Disorder, and Dynamics in Brownmillerite SrFeO.

The room-temperature structure of brownmillerite-type SrFeO remains controversial, despite numerous published crystallographic studies utilizing X-ray, neutron, and electron diffraction data collected on single-crystalline and powder samples. The main disagreements concern the ordering of twisted FeO tetrahedral chains within and between the layers stacked along the axis, and the impact of this ordering on oxide-ionic conductivity. Here, we present new data along with a reinterpretation of previously published diffraction images, including the reassignment of satellite reflections, which harmonize the results of past studies in a unified description of tetrahedral chain ordering in SrFeO at length scales relevant to X-ray and neutron diffraction.

Magnetic Properties of the Distorted Kagomé Lattice Mn(1,2,4-(OC)CH).

Kagomé lattice types have been of intense interest as idealized examples of extended frustrated spin systems. Here we demonstrate how the use of neutron diffraction and inelastic neutron scattering coupled with spin wave theory calculations can be used to elucidate the complex magnetic interactions of extended spin networks. We show that the magnetic properties of the coordination polymer Mn(1,2,4-(OC)CH), a highly distorted kagomé lattice, have been erroneously characterized as a canted antiferromagnet in previous works.

Magnetic ordering and dielectric relaxation in the double perovskite YBaCuFeO.

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.

Dynamics of the frustrated spin in the low dimensional magnet Co₃(OH)₂(C₄O₄)₂.

We describe powder inelastic neutron scattering experiments on a porous coordination polymer Co3(OH)2(C4O4)2, which has two different ordered magnetic phases known to display spin frustrated behaviour, resulting in an idle-spin phase. The moment on each ion is represented by an effective total angular moment J(eff ) =  ½. A non-dispersive magnetic mode was observed in the idle-spin phase which is described by a simple dimer model that assumes ΔJ  =  0.

What difference does a methyl group make: pentamethylbenzene?

The crystal structure of pentamethylbenzene has been obtained for the first time with the use of synchrotron radiation, whilst the low-energy spectrum of lattice dynamics, dominated by the methyl group torsions, was obtained using inelastic neutron scattering. The effect of symmetry lowering by the removal of a single methyl group relative to hexamethylbenzene has been investigated, including the role that this plays in the charge-transfer characteristics of complexes formed with tetracyanoethylene.