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Ferromagnetic Behaviour (ferromagnetic + behaviour)

Distribution by Scientific Domains
Physics and Astronomy57%

Selected Abstracts

A CuIINiII Complex with Ethylenediamine: Crystal Structure and Ferromagnetic Behaviour of an Aqua-Bridged Heterometallic Chain Containing Ambidentate Ni(OAc)42, Blocks

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 22 2010
Oksana V. Nesterova
Abstract A one-pot reaction of copper powder and nickel and ammonium acetates in a CH3OH solution of ethylenediamine (en) yields a unique 1D aqua-bridged polymer [Cu(en)2(,2 -H2O)2Ni(OAc)4]n·4nH2O (1) with an ambidentate Ni(OAc)42, fragment that has not been previously characterized. The basic structural motif of 1 contains a previously unreported heterometallic M(,2 -H2O)M, aqua-bridge chain with alternating metal atoms. A complex system of N/O,H···O hydrogen bonds strengthens the polymeric chains and links them into a supramolecular three-dimensional network. Variable-temperature magnetic susceptibility measurements of 1 revealed a weak ferromagnetic coupling (J = 1.1 cm,1) between the paramagnetic copper(II) and nickel(II) ions, which is transmitted through the oxygen bridges. [source]

Self-Organized Hexagonal Patterns of Independent Magnetic Nanodots,

ADVANCED MATERIALS, Issue 24 2007
T. Bobek
A method for producing self-organised arrays of nanometric metallic dots is reported. It consists on developing first the nanodot pattern by ion erosion on a semiconductor cover film and transferring it to a previously buried metallic layer. This procedure has been applied to Co, and the ferromagnetic behaviour of the dots at room temperature is demonstrated. [source]

Magnetic characterization of U/Co multilayers

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2003
M. A. Rosa
Abstract With the aim of expanding the studies on 2D systems containing uranium, U/Co multilayers with layer thickness ranging from 50 to 200 Å were recently prepared by dc magnetron sputtering onto glass. The multilayers were characterized by Grazing-Incidence X-Ray Diffraction (GIXRD) and Rutherford Backscattering Spectrometry (RBS). Magnetization measurements performed with a squid magnetometer showed that the multilayers have a ferromagnetic behaviour, with the magnetic signal increasing with the thickness of the layers. The analysis of magnetic anisotropy evidenced an easy magnetic direction in the film plane with large anisotropy fields, which increase with the thickness of the layers and suggests a positive contribution of surface anisotropy to the effective anisotropy Keff. [source]

Temperature dependence of a twofold magnetic behaviour of a nanoscopic metal/silicon hybrid system , a comparison between Ni/Si and Co/Si

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 10 2009
K. Rumpf
Abstract The investigated hybrid nanocomposite consists of a porous silicon template with electrochemically embedded Ni or Co nanostructures and offers magnetic characteristics which can be tailored by the electrochemical process parameters during fabrication. A twofold magnetic behaviour can be observed, a first one due to the spinmagnetism at magnetic fields below the saturation magnetization of the deposited metals and a second non-saturating term at higher fields (> 1 T up to 7 T) above the saturation magnetization. In case of Ni deposited within the pores this non-saturating term shows a paramagnetic characteristic and follows exactly the Curie-Weiss law, whereas for Co/porous silicon samples the temperature dependent magnetization shows some deviations from the Curie Weiss law. In this high field region a difference in the temperature dependence between Ni and Co is observed whereas the non-saturating term does not depend on the geometry of the embedded nanostructures in contrast to the ferromagnetic behaviour at lower magnetic fields. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Influence of the Mn compositional distribution on the magnetic order in diluted GaMnN layers

PHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 6 2008
D. Mai
Abstract GaMnN is a prototypical GaN-based dilute magnetic semiconductor (DMS) and its potential as a room temperature ferromagnetic material is still a controversial question to be answered. Diluted GaMnN layers with Mn concentrations up to several percent have been grown by plasma-assisted MBE on MOVPE-GaN templates either on p-Si(111) or on Al2O3(0001) substrates. None of the samples reported here shows second phase precipitates in XRD or in the TEM analysis. However different composition distributions have been evidenced by EDX during the scanning TEM analysis. GaMnN grown at a substrate temperature of TS = 650 °C exhibits extended structural defects and strong compositional inhomogeneity. This could be indicative of decomposition due to local strain. Samples grown at TS = 775 °C with a Mn concentration of about 3% show a homogeneous Mn distribution in the layer. The magnetic properties are found to vary from spin glass to ferromagnetic behaviour at room temperature among different samples. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Syntheses, Structures and Magnetic Properties of Dinuclear Copper(II),Lanthanide(III) Complexes Bridged by 2-Hydroxymethyl-1-methylimidazole

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2008
Wei-Xiong Zhang
Abstract Three discrete dinuclear copper(II),lanthanide(III) complexes, namely, [CuLn(mmi)2(NO3)3(H2O)2] [Ln = La (1), Sm (2)] and [CuGd(mmi)2(NO3)2(H2O)3][NO3] (3) (Hmmi = 2-hydroxymethyl-1-methylimidazole) were synthesized and structurally characterized by X-ray diffraction analysis. In these complexes, dinuclear cores of CuII and LnIII are consolidated by a pair of ,-1,1- O bridges from mmi at a distance of 3.36,3.46 Å. The temperature dependence of the magnetic susceptibility and the field dependence of the magnetization indicate that 1, 2 and 3 exhibit paramagnetic, antiferromagnetic and ferromagnetic behaviours, respectively. The value of the JCu,Gd coupling constant of 3 [8.7(1) cm,1] is fairly large, which is probably related to the small dihedral angles, , (5.0°), between the two planes of O,Cu,O and O,Gd,O in the CuO2Gd core.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]

Magnetotransport and magnetic properties of p -Zn1, xMnxTe:N , Carrier-induced ferromagnetism

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 3 2004
K.-T. Nam
Abstract The magnetic properties of nitrogen-doped p -Zn1, xMnxTe grown by MBE were studied through the magnetotransport measurements. In a sample of p -Zn1, xMnxTe with x = 0.034 and p = 4.7 × 1019 cm,3, a hysteresis loop was observed below 2.5 K in the Hall resistance and the magnetoresistivity, which indicates the ferromagnetic transition. From the plot of (RHall/Rsheet)2 against B/(RHall/Rsheet) at several temperatures, which corresponds to the so-called Arrott plot, we can estimate the Curie temperature (Tc) of the sample as about 3 K, suggesting that this sample has the higher Tc than ever reported. We also demonstrated, by means of light irradiation, that the strength of ferromagnetic interactions can be controlled by changing the hole concentration. An increase of the ferromagnetic behaviours such as a small increase of the coercive field was observed under light irradiation. This result strongly supports that the ferromagnetic transition in Zn1, xMnxTe is the carrier-induced one. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]