26 research outputs found
Insights into the magnetic dead layer in La0.7Sr0.3MnO3 thin films from temperature, magnetic field and thickness dependence of their magnetization
Experimental investigations of the magnetic dead layer in 7.6 nm thick film of La0.7Sr0.3MnO3 (LSMO) are reported. The dc magnetization (M) measurements for a sample cooled to T = 5 K in applied field H = 0 reveal the presence of negative remanent magnetization (NRM) in the M vs. H (magnetic field) measurements as well as in the M vs. T measurements in H = 50 Oe and 100 Oe. The M vs. T data in ZFC (zero-field-cooled) and FC (field-cooled) protocols are used to determine the blocking temperature TB in different H. Isothermal hysteresis loops at differ- ent T are used to determine the temperature dependence of saturation magnetization (MS), remanence (MR) and coercivity HC. The MS vs. T data are fit to the Bloch law,MS (T)=M0 (1–BT 3/2),showingagoodfitforT \u3c100Kandyieldingthe nearest-neighbor exchange constant J/kB 18 K. The variations of TB vs. H andHC vs. T are well described by the model often used for randomly oriented mag- netic nanoparticles with magnetic domain diameter ≈ 9 nm present in the dead-layer of thickness d =1.4 nm. Finally, the data available from literature on the thickness (D) variation of Curie temperature (TC) and MS of LSMO films grown under 200, 150, and 0.38 mTorr pressures of O2 are analyzed in terms of the finite-size scaling, with MS vs. D data fit to MS (D) = MS(b)(1-d/D) yielding the dead layer thickness d = 1.1 nm, 1.4 nm and 2.4 nm respectively
Magnetic Properties of the Novel Low-Dimensional Cuprate Na5RbCu4(AsO4)4Cl2
The magnetic properties of a new compound, Na5RbCu4(AsO4)4Cl2 are reported.
The material has a layered structure comprised of square Cu4O4 tetramers. The
Cu ions are divalent and the system behaves as a low-dimensional S=1/2
antiferromagnet. Spin exchange in Na5RbCu4(AsO4)4Cl2 appears to be
quasi-two-dimensional and non-frustrated. Measurements of the bulk magnetic
susceptibility and heat capacity are consistent with low-dimensional magnetism.
The compound has an interesting, low-entropy, magnetic transition at T = 17 K.Comment: 4 pages, 5 figure
Charge disproportionation in YNiO : ESR and susceptibility study
We present a study of the magnetic properties of YNiO in the
paramagnetic range, above and below the metal-insulator (MI) transition. The dc
susceptibility, (measured up to 1000 K) is a decreasing function of
T for 150 K (the N\'{e}el temperature) and we observe two different
Curie-Weiss regimes corresponding to the metallic and insulator phases. In the
metallic phase, this behaviour seems to be associated with the small ionic
radius of Y% . The value of the Curie constant for T T allows
us to discard the possibility of Ni localization. An electron spin
resonance (ESR) spectrum is visible in the insulator phase and only a fraction
of the Ni ions contributes to this resonance. We explain the ESR and behaviour for T T in terms of charge disproportionation of
the type 2Ni Ni+Ni that is compatible with the
previously observed structural transition across T.Comment: 10 pages, 4 figures, submitted to Phys. Rev.
Magnetic properties of the frustrated AFM spinel ZnCr_2O_4 and the spin-glass Zn_{1-x}Cd_xCr_2O_4 (x=0.05,0.10)
The -dependence (2- 400 K) of the electron paramagnetic resonance (EPR),
magnetic susceptibility, , and specific heat, , of the
antiferromagnetic (AFM) spinel ZnCrO and the spin-glass
(SG) ZnCdCrO () is reported. These
systems behave as a strongly frustrated AFM and SG with K and -400 K K. At high-
the EPR intensity follows the and the -value is -independent.
The linewidth broadens as the temperature is lowered, suggesting the existence
of short range AFM correlations in the paramagnetic phase. For
ZnCrO the EPR intensity and decreases below 90 K and 50
K, respectively. These results are discussed in terms of nearest-neighbor
Cr (S %) spin-coupled pairs with an exchange coupling of 50 K. The appearance of small resonance modes for K,
the observation of a sharp drop in and a strong peak in
at K confirms, as previously reported, the existence of long range
AFM correlations in the low- phase. A comparison with recent neutron
diffraction experiments that found a near dispersionless excitation at 4.5 meV
for and a continuous gapless spectrum for ,
is also given.Comment: 17 pages, 8 figures, 1 Table. Submitted to Physical Review
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QUANTIFICATION OF MERCURY IN FLUE GAS EMISSION USING BORON-DOPED DIAMOND ELECTROCHEMISTRY
In this project, we have attempted to develop a new technique utilizing Boron-doped diamond (BDD) films to electrochemically detect mercury dissolved in solution via the initial deposition of metallic mercury, followed by anodic linear sweep voltammetry in the range from 10-10{sup -10} M to 10{sup -5} M. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were employed. The extremely low background current for BDD electrodes compared to glassy carbon (GC) provides a strong advantage in trace metal detection. CV peak currents showed good linearity in the micromolar range. A detection level of 6.8 x 10{sup -10} M was achieved with DPV in 0.1 M KNO{sub 3} (pH = 1) for a deposition time of 20 minutes. Reproducible stripping peaks were obtained, even for the low concentration range. A comparison with GC shows that BDD is superior. Linear behavior was also obtained in the mercury concentration range from 10{sup -10} M to 10{sup -9} M
Information for oral and maxillofacial patients:can it be improved?
The aim and objective of this study was to evaluate the quality and readability of leaflet and online Oral and Maxillofacial Surgery patientinformation leaflets (PILs). The quality, readability and grade level of each PIL was assessed using the DISCERN, Flesch Reading Easeand Flesh-Kincaid Grade Level instruments respectively. In total, 140 patient information leaflets were assessed. For both leaflet and onlinePILs, many items of the DISCERN instrument were deemed of low quality and poorly reported. The median overall quality score was 30.2.Variation in the quality and readability scores between leaflet and online PILs and those produced by various societies was evident. Overall,PILs were deemed to be of moderate quality. Online PILs were of lower quality, more difficult to read and aimed at a higher reading age level