Phase formation and ferrimagnetism of GdCo9Si4 (original) (raw)

Magnetic entropy change in GdCo13−xSix intermetallic compounds

Journal of Magnetism and Magnetic Materials, 2010

The magnetic entropy change in GdCo 13 À x Si x (x¼ 3.8, 4, 4.1, and 4.2) intermetallic compounds has been investigated by means of magnetic measurements in the vicinity of their Curie temperature. It was found that the magnetic ordering temperatures decrease from 60 K at x¼ 3.8 to 28 K for x¼ 4.2. The magnetic entropy change is calculated from isothermal magnetization versus magnetic field at various temperatures using the Maxwell relation. As a result, the maximum magnetic entropy changes of the investigated compounds, at their Curie temperatures, decrease from 11.5 J/kg K for x¼ 4.2 to 6.86 J/kg K for x¼ 3.8 in a field change of 0-3 T, whereas it decreases from 5.13 J/kg K for x¼ 4.2 to 2.60 J/kg K for x¼ 3.8 in a field change of 0-1 T. Moreover, the maximum value of the magnetic entropy change obtained at a higher field for GdCo 13 À x Si x with x¼ 4 (23.75 J/kg K at 5 T) is comparable to that of various types of compounds with a cubic NaZn 13-type structure. Finally, the maximum of the magnetic entropy change is found to decrease with increasing Si content.

A combined study of the magnetic properties of GdCrO 4

Journal of Physics: Condensed Matter, 2006

We have performed a detailed study of the magnetic properties of GdCrO 4 at low temperatures by complementary use of different macroscopic and microscopic physical techniques. A ferromagnetic order is established in this oxide below T C = 22 K. The ordered magnetic moments of the Cr 5+ ions are located along the crystallographic c-axis, forming an angle of ≈24 • with the ordered moments of the Gd 3+ ions. Surprisingly, only 20% of the Gd 3+ sublattice orders at the Curie temperature of 22 K, while the remaining 80% stays paramagnetic down to around 10 K. This 80% of the Gd 3+ ions may be ascribed to a lowtemperature orthorhombic phase. Moreover, the Gd 3+ magnetic order seems to be triggered by a relatively large transferred hyperfine field coming from the Cr 5+ sublattice.

Magnetic structure of GdCo2Ge2

Physical Review B, 2005

Resonant and nonresonant magnetic x-ray scattering studies of GdCo 2 Ge 2 were performed to determine its magnetic structure at low temperature. This compound orders in an incommensurate antiferromagnetic ͑AF͒ structure characterized by a propagation wave vector = ͑0 0 z ͒. The value of z is temperature dependent and approaches 0.930 reciprocal lattice units well below T N = 33.25 K. A peak corresponding to 3 z was also observed, indicating either a squaring up of the magnetic structure or the presence of a noncollinear amplitude modulated structure below T N . Fitting the angular dependence of the magnetic scattering integrated intensities to the relevant resonant and nonresonant scattering cross sections revealed that the moment direction lies primarily in the tetragonal basal plane. Scattering measurements at the Co K-edge failed to detect any resonant signal, consistent with the absence of a magnetic moment on the Co sites.

High magnetic field study of the Gd-Co exchange interactions in GdCo12B6

Journal of Applied Physics, 2012

Electromagnetic and absorption properties of urchinlike Ni composites at microwave frequencies J. Appl. Phys. 111, 093905 (2012) Influence of boron doping on magnetic properties and microwave characteristics of MnIr/FeCoB multilayers J. Appl. Phys. 111, 083920 Self consistent measurement and removal of the dipolar interaction field in magnetic particle assemblies and the determination of their intrinsic switching field distribution J. Appl. Phys. 111, 083914 (2012) Geometric influence on Ruderman-Kittel-Kasuya-Yosida interactions in zigzag carbon nanotubes J. Chem. Phys. 136, 154504 (2012)

Critical magnetic behavior of magnetocaloric materials with the Gd[sub 5]Si[sub 4]-type structure

Journal of Applied Physics, 2013

An extensive investigation on the magnetism of Gd 5 ðSi x Ge 1Àx Þ 4 compounds which stabilize in the Gd 5 Si 4 -type structure is here presented, focusing on the Gd 5 Si 4 and Gd 5 Si 2 Ge 2 compositions. Through Arrott plot analysis, the temperature dependencies of the spontaneous magnetizations are retrieved and the magnetic interaction coefficients (J exch ) are estimated. The obtained J exch value for Gd 5 Si 4 is 15% higher than that of Gd 5 Si 2 Ge 2 . Such enhancement cannot be attributed to a magneto-volume coupling only, being mainly associated with the magnetic polarization of the (Si,Ge)-(Si,Ge) interslab connections. The critical exponents were estimated (d ¼ 3:1 and 2.9, c ¼ 1:01 and 1:06; b ¼ 0:48 and 0.56, and n ¼ 0:67 and 0.63 for Gd 5 Si 4 and Gd 5 Si 2 Ge 2 , respectively) demonstrating that both compositions belong to the same universal class. This conclusion is reinforced by the construction of a universal logarithmic scaling plot of the M(H) isothermal curves. Hence, we conclude that the magnetism of the Gd 5 Si 4 -type structure compounds is simply dominated by long range ferromagnetic interactions. This contrasts to other Gd 5 ðSi x Ge 1Àx Þ 4 compositions where a strong competition antiferro versus ferromagnetic interactions and short versus long range order are observed. Finally, the Gd 5 Si 4 composition has shown a reduction of 50% on the magnetic entropy change maxima when compared with the Gd 5 Si 2 Ge 2 compound studied, despite its higher magnetic interaction coefficient value. V C 2013 American Institute of Physics.

Gd Substitution Effects on the Magnetic Properties of the Pr1−x Gd x Co4Si Compounds

Journal of Superconductivity and Novel Magnetism, 2012

The crystal structure and magnetic properties of single phase Pr 1−x Gd x Co 4 Si compounds with x = 0, 0.2, 0.4, 0.6, 0.8, and 1.0 have been investigated. X-ray analysis reveals that the compounds crystallize as a single phase having the hexagonal CaCu 5-type structure with the space group P 6/mmm. The substitution of Gd for Pr causes a linear decrease of the unit-cell parameters a and c, and the unit-cell volume V. Magnetic measurements indicate that all samples are ordered magnetically below the Curie temperature. The saturation magnetization at 4.2 K decreases upon the Gd substitution up to x = 0.6, and then increases.

The preferential site occupation and magnetic properties of GdxY2−xO3

Journal of Physics and Chemistry of Solids, 1993

Abstra&-The gadolinium-yttrium mixed oxides Gd,Y,_,O, were synthesized over a wide range of concentrations: x = 0.10, 0.18, 0.41, 0.74 and 1.26. The X-ray diffraction data from the polycrystalline samples were taken at room temperature and refined using the Rietveld method. Gadolinium-yttrium oxides crystallize in the space group Ia3. The cations occupy the six coordinated positions 8b and 24d. The anion occupies a general tetrahedrally coordinated position. At concentrations x Q 0.41 gadolinium ion occupies exclusively 24d, but at higher concentrations the occupation of position 86 increases continuously. The magnetic susceptibility measurements showed the presence of the antiferromagnetic interaction in all samples. The magnetic moment in the sample x = 1.26 is significantly different from the magnetic moment of the free ion Gd 3+. The Cur&Weiss temperature shows a nonlinear dependence on concentration.