Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2

Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T. The analysis of data, assuming the combined effect of inter-layer superexchange and the phase separation into mesoscopic magnetic domains with localized spins embedded in a matrix with itinerant electronic character, suggests that the dominant contribution to the specific heat in the region of short-range ordering is mediated by quasi-2D antiferromagnetic clusters, perpendicular to the CoO2 layers

Magnetotransport properties of CaTixRu1-xO3 (x=0, 0.07)

Electrical resistance, transversal magnetoresistance and the Hall effect were studied on polycrystalline CaTixRu1-xO3 (x = 0, 0.07) samples using a conventional Quantum Design PPMS-9 equipment in the temperature range 2-300 K and magnetic field up to 9 T. Substantial differences were found between the two samples: (i) opposite to the metallic character of CaRuO3, the substituted sample has insulating-like electrical resistance; (ii) the magnetoresistance of the substituted sample changes the sign from negative to positive values with increasing temperature. The magnetoresistance of CaRuO3 is negative, the sign reversal is induced by magnetic field and only at temperatures below 15 K, such a behaviour is predicted for clustered systems; (iii) the Hall voltage in pure CaRuO3 also changes sign from negative to positive values above 35 K. This temperature coincides with the observed magnetic transition temperature, indicating that the magnetic state and the carrier character interrelate.13th Czech and Slovak Conference on Magnetism (CSMAG07), Jul 09-12, 2007, Kosice, Slovaki

Ti-induced ferromagnetism and the specific heat of CaTixRu1-xO3 (x=0, 0.005, 0.03)

The influence of Ti substitution on the specific heat of the CaTixRu1-xO3 system at low concentrations x = 0, 0.005, and 0.03 was studied in the temperature range of 2-300 K at magnetic fields tip to 9 T. Small peak was revealed in the C/T vs. T-2 dependence at around 3 K, which are field sensitive (the electronic specific heat coefficient gamma linearly decreases with the increase in magnetic field), and might be connected to some kind of magnetic ordering. The coefficient gamma is suppressed also by Ti substitution.13th Czech and Slovak Conference on Magnetism (CSMAG07), Jul 09-12, 2007, Kosice, Slovaki

Low temperature anomalies in the specific heat and magnetic susceptibility of Na0.7CoO2 samples

We present a comparative study of Na0.7CoO2 samples obtained from three different sources and prepared by different methods. The specific heat and magnetic susceptibility measurements in the temperature range 2-300 K show substantial influence on the observed anomalies, which underlines that the system is extremely sensitive to preparation protocols.13th Czech and Slovak Conference on Magnetism (CSMAG07), Jul 09-12, 2007, Kosice, Slovaki

Nevoid basal cell carcinoma syndrome (Gorlin syndrome)

Nevoid basal cell carcinoma syndrome (NBCCS), also known as Gorlin syndrome, is a hereditary condition characterized by a wide range of developmental abnormalities and a predisposition to neoplasms

[Portrait of Hector Harrison, 1951] [picture].

Title devised by cataloguer.; Inscription: "Yours sincerely, Hector Harrison, 1951" -- In pencil on mount.; Related material: Papers of Hector Harrison ; National Library of Australia manuscript collection MS 6277.; Related material: Interview with Reverend Hector Harrison ; National Library of Australia oral history collection ORAL TRC 121/46

Thermodynamic properties of Na0.65CoO2

Specific heat of the layered Na0.65CoO2 powder sample over the temperature region of 3-360 K has been studied. Features hinting at charge ordering below room-temperature were observed. Magnetic phase transition at 28 K as well as signs of short-range ordering confirm the 2D character of magnetism with weak inter-planar coupling in the system. Comparison to different 2D antiferromagnetic models suggests that the magnetic lattice is more square- than triangular-like, what could be favoured by the charge ordering.12th Czech and Slovak Conference on Magnetism, Jul 12-15, 2004, Kosice, Slovaki

5f Magnetism Studied in Complex Intermetallic U-based Hydrides

Hydrogen absorption in uranium ternary intermetallic compounds typically increases ordering temperatures and magnetic moments. The case of URuSn hydride, which does not behave accordingly, can be related to specific H positions revealed by neutron diffraction on deuterides. Tuning through the onset of magnetic ordering by means of H absorption was found for the U2T2X compounds as U2Co2Sn. For U2Ni2SnD1.8, we demonstrated that the anisotropic lattice expansion leads to U moments reorientation, as a result of hybridisation-induced two-ion anisotropy,with respect to U2Ni2Sn, in which the U U coordination is poised between two regimes.JRC.E.6-Actinides researc

Influence of Ti4+ on the magnetic state of CaRu1-xTixO3

In order to shed more light on the character of magnetic correlations at low temperatures in CaRuO3, the delicate effect of substituting nonmagnetic Ti4+ for Ru4+ in low concentrations (0.5-15%) has been investigated by magnetization, AC-susceptibility and specific heat measurements. Despite the clear features in magnetic measurement data at 34K no specific heat anomaly has been observed, nevertheless, two temperature regions with different magnetic characters have been identified. . In pure CaRuO3 sisignificant low-temperature upturn of C/T is visible below 15 K. This feature is suppressed by Ti substitution. (c) 2007 Elsevier B.V. All rights reserved.Joint European Magnetic Symposia (JEMS 06), Jun 26-29, 2006, San Sebastian, Spai

Comprehensive Study of the Low-​Temperature Transport and Thermodynamic Properties of the Cluster Compounds AgxMo9Se11 (3.41 ≤ x ≤ 3.78)

International audienceThe authors present a detailed study of the evolution of the elec., galvanomagnetic, and thermodn. properties of polycryst. AgxMo9Se11 compds. for 3.4 ≤ x ≤ 3.8 at low temps. (2-​350 K)​. In agreement with d. functional theory calcns., the collected data show an overall gradual variation in the transport properties from metallic to semiconducting behavior on going from x = 3.4 to 3.8. The results evidence subtle variations in the electronic properties with the Ag content, typified by both pos. and neg. phonon-​drag effects together with thermopower and Hall coeff. of opposite signs. Anal. of the data suggests that these features may be due to peculiarities of the dispersion of the valence bands in the vicinity of the chem. potential. A drastic influence of the Ag content on the thermal transport was evidenced by a pronounced change in the temp. dependence of the sp. heat <10 K. Nonlinearities in the Cp(T3) data are correlated to the concn. of Ag atoms, with an increase in x resulting in a more pronounced departure from a Debye law. The obsd. behavior mirrors that of ionic conductors, suggesting that AgxMo9Se11 for x ≥ 3.6 might belong to this class of compds