Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound (original) (raw)
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The unusual magnetic and electronic properties of Gd0.5Ba0.5CoO2.9
Journal of Physics and Chemistry of Solids, 2004
Magnetic and electrical properties of well-characterized Gd 0.5 Ba 0.5 CoO 2.9 have been studied carefully in order to compare them with those of other analogous cobaltates of the type Ln 0.5 A 0.5 CoO 3 (Ln ¼ La, Nd and A ¼ Sr, Ba) which are ferromagnetic. The results show that Gd 0.5 Ba 0.5 CoO 2.9 , which has A-site cation ordering at room temperature, does not become a genuine ferromagnet at low temperatures, but the ferromagnetic interactions observed at 280 K give over to an antiferromagnetic (AFM) state on cooling to 230 K. The AFM state is rendered ferromagnetic on the application of high magnetic fields. The properties can be understood on the basis of phase separation induced by the large A-site cation-disorder, arising from the size mismatch. q
Magnetic phase transitions in Gd3Co
Journal of Alloys and Compounds, 1993
Magnetization, electrical resistivity, thermal expansion, magnetostriction and sound velocity were measured for Gd3Co single crystals. The compound has an orthorhombic Fe3C-type crystal structure and exhibits an antiferromagnetic arrangement of Gd magnetic moments below TN = 131 K. First-order phase transitions from the antiferromagnetic to the forced ferromagnetic state are observed along the b and c axes at a critical field He--0.8 T. Along the a axis, Gd3Co also becomes a forced ferromagnet at approximately 1.5 T, but the magnetization process occurs by the rotation of Gd magnetic moments. An antiferromagnetic ordering of the Co sublattice appears below T* =3.7 K. Anisotropy of the electrical resistivity is found below TN. The field-induced antiferromagnetic to ferromagnetic transitions are accompanied by large magnetoresistance (Ap/po= --50%) and magnetostriction (A//l--3.8×10 -4) as well as by a large change of the sound velocity of the shear wave in the bc plane (from 675 m s-i down to 220 m s-~). Magnetic phase diagrams of Gd3Co are given for different directions of the applied field.
Yb-doped Gd 2 O 2 CO 3 : Structure, microstructure, thermal and magnetic behaviour
Journal of Physics and Chemistry of Solids, 2017
Structural and microstructural features, as well as thermal and magnetic properties of Yb-doped Gd 2 O 2 CO 3 , were investigated with the aim to clarify the location and the oxidation state of Yb within the structure, and its role in driving the extent of the (Gd 1-x Yb x) 2 O 2 CO 3 solid solution. Yb is found in the 3+ oxidation state and it enters the structure only at the rare earth atomic site; the solubility limit results to be located in the close vicinity of x = 0.25, and thermal analyses reveal a linear decrease of the decomposition temperature with increasing the Yb amount, in agreement with literature data. The structural analysis allows to exclude long-range clusterization of Yb and Gd, since both rare earths randomly distribute over the 4f atomic position, but relying on the results of the microstructural analysis, the presence of compositional inhomogenities at the local scale cannot be excluded.
Magnetic properties of (GdxY1−x)Co2B2 compounds
Journal of Magnetism and Magnetic Materials, 1993
Magnetic measurements were performed on the (Gd,Yr_,)Co,B, compounds, in the temperature range 2-800 K and fields up to 70 kOe. YCo,B, is a paramagnet. The (Gd,Y,_,jCo,B, compounds with x t 0.2 shows a ferromagnetic type ordering. The saturation magnetization at 2 K coincides only with the contribution of gadolinium. The Curie temperatures are nearly linearly dependent on the composition. Above the Curie points, the thermal variations of the magnetic susceptibility can be described as a superposition of a temperature independent term x0 on a Curie-Weiss behavior. The Curie constants are determined by the contribution of Gd 3+ ions only. The x0 values increase when the gadolinium content is greater. The observed properties are discussed in the wider framework of the magnetic behavior of cobalt in GdCo,B, compounds.
Rare-earth tetraborides RB4 are of great interest due to the occurrence of geometric magnetic frustration and corresponding unusual magnetic properties. While the Gd3+ spins in GdB4 align along the ab plane, Er3+ spins in the isomorphic ErB4 are confined to the c–axis. The magnetization in the latter exhibits a plateau at the midpoint of the saturation magnetization. Therefore, solid solutions of (Gd, Er)B4 provide an excellent playground for exploring the intricate magnetic behavior in these compounds. Single crystals of Gd(1-x)Erx B4 (x = 0, 0.2, and 0.4) were grown in aluminum flux. X-ray diffraction scans revealed single phase materials, and a drop in the unit cell volume with increasing Er content, suggesting the partial substitution of Er at the Gd sites. Heat capacity measurements indicated a systematic decrease of the Néel temperature (TN) with increasing Er content. The effective magnetic moment determined from the magnetization measurement agreed with the calculated free-i...
Journal of Physics and Chemistry of Solids, 2008
The crystal and magnetic properties of the Nd 1Àx Gd x Co 4 B compounds for 0pxp1 have been studied by X-ray powder diffraction, magnetization and differential scanning calorimetry (DSC) measurements. These compounds crystallize in a hexagonal CeCo 4 B-type structure with the P6/mmm space group. The substitution of Gd for Nd leads to a decrease of the unit-cell parameter a and the unit-cell volume V, while the unit-cell parameter c remains almost constant. Magnetic measurements indicate that all samples are ordered magnetically below room temperature. The Curie temperatures determined by the DSC technique increase linearly as Nd is substituted by Gd. The saturation magnetization at 5 K decreases upon the Gd substitution up to x ¼ 0.6, and then increases again.
On the magnetic properties of the Y1−xGdxCo4B compounds
Solid State Communications, 1992
Magnetic phase transitions in Yl.xGdxCO4 B with x ranging from 0 to 1 have been determined in the temperature range of 77 to 600K. The compensation temperature is found in the compounds with x ~ 0.6,while in the rest compounds a spin reorientation from the c-axis towards the basal plane upon decreasing temperature is observed. On the basis of the observed Curie and compensation temperatures the intersublattice exchange interaction coefficient has been derived and the contribution of the anisotropic exchange interaction to the anisotropy energy of the Gd containing compounds has been estimated.
Study of structural and magnetic properties of Gd2MoO6 compound
PROCEEDINGS OF THE INTERNATIONAL CONFERENCE ON ADVANCED MATERIALS: ICAM 2019, 2019
In this present work, we study the structural, microstructural, electronic and magnetic properties of Gadolinium M olybdate (Gd 2 M oO 6) compound synthesized via solid statereactionmethod. The single-phase nature of the compound is confirmed using x-ray diffraction (XRD) technique and the structure is refined to monoclinic symmetry (C2/c, Space group 15). Surface imaging of the sample shows agranular type morphology of about 0.1 µm.X-ray photoelectron spectroscopic measurements reveal mixed valent (4+/6+) charge states in case of M o and also the presence of oxygen vacancies in Gd 2 M oO 6. M agnetization measurements performed using 7T SQUID VSM reveal an overall antiferromagnetic behavior.
Large magnetocaloric effect and magnetoresistance behavior in Gd4Co3
The European Physical Journal B, 2008
We report a large entropy change (∆S) below 300 K, peaking near T C = 220 K, due to isothermal change of magnetic field, for Gd 4 Co 3 , with a refrigeration capacity higher than that for, say, LaFe 11.4 Si 1.6 , ordering magnetically in the same temperature range. A noteworthy finding is that the isothermal magnetization is nonhysteretic-an important criterion for magnetic refrigeration without loss. ∆S behavior is also compared with that of magnetoresistance.
Canted magnetic structure arising from rare-earth mixing in the Laves-phase compound (Nd0.5Tb0.5)Co2
Physical Review B, 2006
The crystal and magnetic structures of Laves-phase compound ͑Nd 0.5 Tb 0.5 ͒Co 2 have been investigated by high resolution neutron powder diffraction at different temperatures. Magnetization measurement and neutron diffraction reveal two magnetic transitions at T C Ϸ 173 K and T M Ϸ 47 K, respectively. At room temperature, the compound crystallizes in the MgCu 2-type ͑C15͒ structure. Below T C , rhombohedral distortion and large anisotropic magnetostriction take place and persist down to 4 K. In contrast to the binary rare earth ͑R͒-Co Laves-phases RCo 2 , a noncollinear magnetic structure ͑canted͒ is deduced for ͑Nd 0.5 Tb 0.5 ͒Co 2 , based on the Rietveld refinement of the neutron diffraction data at 50 K and 4 K. In addition, the correlation between lattice distortion and easy magnetization direction ͑EMD͒ commonly observed for binary RCo 2 is violated in ͑Nd 0.5 Tb 0.5 ͒Co 2. Though the crystal structure remains rhombohedral, the EMD of the R sublattice is close to the ͓110͔ direction at 50 K of the pseudocubic lattice and along the ͓111͔ direction at 4 K, respectively. The difference of the canting angle between the magnetic structures at 50 K and 4 K is small, indicating stable canted configurations. The lattice parameters exhibit a discontinuity around T M , suggesting a first-order transition between the two canted magnetic structures. The dilution of magnetic anisotropy of the R sublattice and the contribution of the magnetic anisotropy of the Co sublattice are responsible for the observations.