Spin polarisation and non-isotropic effective mass in the conduction band of GdN.

GdN is a ferromagnetic semiconductor which has seen increasing interest in the preceding decades particularly in the areas of spin- and superconducting- based electronics. Here we report a detailed computational and optical spectroscopy study of the electronic structure of stoichiometric and nitrogen vacancy doped GdN. Based on our calculations we provide the effective mass tensor for undoped GdN, and some indicative values for electron doped GdN.

Indications of a ferromagnetic quantum critical point in [Formula: see text].

We investigate the previously observed superconductivity in ferromagnetic SmN in the context of the breakdown of order between two magnetic phases. Nitrogen vacancy doped SmN[Formula: see text] is a semiconductor which lies in the intermediary between ferromagnetic SmN and anti-ferromagnetic Sm. Optical data reported here corroborate the prediction that electrical transport is mediated by Sm 4f defect states, and electrical transport measurements characterise the metal-insulator transition over the doping range.

Removable capping layer for air-sensitive GdN.

The strongly correlated rare earth nitrides display unusual coupled magnetic, electronic and superconducting properties, with predicted topological states. However, their air-sensitiveness has prevented in-depth investigations of their properties. In this paper, we show that a 100 nm thick epitaxial samarium layer provides adequate passivation of 100 nm thick thin films of gadolinium nitride (GdN), the prototypical rare earth nitride, enabling ex-situ magnetic and structural characterizations.

Vertical transport and tunnelling in rare-earth nitride heterostructures.

We report an investigation of the ferromagnetic semiconductor rare earth nitrides (RENs) for their potential for cryogenic-temperature electronics and spintronics applications. We have identified ohmic contacts suitable for the device structures that demand electron transport through interface layers, and grown REN/insulator/REN heterostructures that display tunnelling characteristics, an enormous 400% tunneling magnetoresistance and a hysteresis promising their exploitation in non-volatile magnetic random access memory.

Breaking Molecular Nitrogen under Mild Conditions with an Atomically Clean Lanthanide Surface.

A route to break molecular nitrogen (N) under mild conditions is demonstrated by N gas cracking on, and incorporation into, lanthanide films. Successful growth of lanthanide nitride thin films, made by evaporation of lanthanides in a partial N atmosphere at room temperature and pressure as low as 10 Torr, is confirmed using X-ray diffraction. In situ conductance measurements of pure lanthanide thin films exposed to N gas show an immediate surface reaction and a slower bulk reaction.

Nucleation and annihilation of skyrmions in MnCoAl observed through the topological Hall effect.

Magnetic skyrmions are topologically protected spin textures with great technological potential. These topologically non-trivial non-coplanar spin textures give rise to a topological Hall effect, enabling the purely electronic detection of magnetic skyrmions. We report a clear topological Hall effect in thin films of the the Heusler alloy MnCoAl, a ferromagnetic spin-gapless semiconductor, capped by a thin layer of Pd.

Realizing field-dependent conduction in ZnO nanowires without annealing.

We report on the low-temperature fabrication of field-effect transistors by bridging pre-patterned electrodes using ZnO nanowires grown in situ, which operate without requiring post-growth processing or annealing. The devices show good performance using as-grown nanowires, with on-off ratios of 10 and threshold voltages of 2 V. Electron microscopy shows the field-dependent nanowires hierarchically nucleate from larger ZnO nanorods, and both are oriented along a common c-axis.

Europium nitride: a novel diluted magnetic semiconductor.

Europium nitride is semiconducting and contains nonmagnetic Eu3+, but substoichiometric EuN has Eu in a mix of 2+ and 3+ charge states. We show that at Eu2+ concentrations near 15%-20% EuN is ferromagnetic with a Curie temperature as high as 120 K. The Eu3+ polarization follows that of the Eu2+, confirming that the ferromagnetism is intrinsic to the EuN which is, thus, a novel diluted magnetic semiconductor.

Hot-injection synthesis of iron/iron oxide core/shell nanoparticles for T2 contrast enhancement in magnetic resonance imaging.

Here we report a new, bench-top synthesis for iron/iron oxide core/shell nanoparticles via the thermal decomposition of Fe(η(5)-C(6)H(3)Me(4))(2). The iron/iron oxide core/shell nanoparticles are superparamagnetic at room temperature and show improved negative contrast in T(2)-weighted MR imaging compared to pure iron oxides nanoparticles, and have a transverse relaxivity (r(2)) of 332 mM(-1) s(-1).

Evidence from the surface morphology for nonlinear growth of epitaxial GaAs films.

The mesoscale morphology of homoepitaxial GaAs surfaces is explained with an anisotropic and nonlinear Kardar-Parisi-Zhang (KPZ) model in which adatoms are incorporated into the film from a metastable surface layer. Evaporation-condensation between the film and the metastable layer is proposed as the microscopic physical origin of the KPZ description, as well as of the excess noise observed in the power spectral density. The parabolic mounds observed experimentally in films grown on rough substrates are in good agreement with the surface shape expected from the solution of the KPZ equation in the large amplitude limit.

Pattern of shedding of two noncultivable viruses in stools of newborn babies.

Noncultivable viruses have been associated with diarrhea affecting newborn babies in obstetric hospital nurseries. Persisting infection in a special care nursery in Melbourne, Australia, permitted a study of the pattern of excretion of these viruses. Ten babies admitted to the nursery within 2 hr of birth were randomly selected for prospective study.

Is lactase the receptor and uncoating enzyme for infantile enteritis (rota) viruses?

Rotaviruses are now regarded as important causes of diarrhoea in man, cattle, pigs, mice, and possibly other animals. Characteristically, disease occurs in newborn and young animals, and infection seems limited to the differentiated gut epithelial cells. The major surface polypeptide of the calf scours rotavirus is glycosylated, and highly purified beta-galactosidase (lactase) interacts with the virus in vitro causing removal of the outer shell of the capsid (uncoating).

The aetiology of diarrhoea in newborn infants.

Diarrhoea is a common problem in newborn infants in hospital nurseries. In the past, sporadic diarrhoea was often attributed to dietary indiscretion by the mother, and epidemic diarrhoea was though to be caused by an unknown infectious agent. Techniques with which to locate non-cultivable viruses and untypable enteropathogenic strains of Escherichia coli allow reevaluation of the aetiology of diarrhoea in newborn infants.

An epidemic of diarrhoea in human neonates involving a reovirus-like agent and 'enteropathogenic' serotypes of Escherichia coli.

During December 1974, an epidemic of diarrhoea occurred in the Royal Children's Hospital, Melbourne, in a ward caring for neonates with acute or chronic medical and surgical problems. Electron microscopy of diarrhoeal faeces revealed a reovirus-like particle ('duovirus' or 'rotavirus') known to cause acute enteritis in older children. This virus is considered to have been primarily involved in the aetiology of the epidemic.

Immunofluorescence in duodenal mucosa of children with acute enteritis due to a new virus.

Electron microscopy od duodenal mucosa from children with acute non-bacterial enteritis has shown virus particles in epithelial cells. Indirect immunofluorescent techniques applied to the same tissue showed virus antigen localized in the cytoplasm of epithelial cells of the villi. Specific IgM antibody was present in sera from infected patients as early as two days after the onset of symptoms.