Magnetism and hyperfine interactions in Gd2Ni2Mg (original) (raw)
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ChemInform Abstract: Magnetism and Hyperfine Interactions in Gd2Ni2Mg
ChemInform, 2001
Gd 2 Ni 2 Mg was synthesised by reaction of the elements in a sealed tantalum tube in a high-frequency furnace. The structure was investigated by single crystal X-ray diffraction: Mo 2 FeB 2 type, P 4/mbm, a = 743.8(1), c = 375.3(1) pm, wR 2 = 0.0560, 256F 2 values, 12 variables. The Gd 2 Ni 2 Mg structure is an intergrowth of distorted AlB 2 and CsCl slabs of compositions GdNi 2 and GdMg. The magnetic phase transitions were studied by AC and DC magnetic susceptibility measurements and 155 Gd Mössbauer spectroscopy. Antiferromagnetic ordering is detected at T N = 49.00(5) K followed by two further transitions at T f1 = 20.70(5) and T f2 = 4.5(1) K, respectively. Non-vanishing second and third harmonic components of the induced voltage under application of a small AC magnetic field reveal the ferromagnetic nature of the second transition at T f1 . Below T f1 , Gd 2 Ni 2 Mg shows strong irreversibility between field cooled (FC) and zero field cooled (ZFC) DC magnetization and magnetic hysteresis behaviour. 2001 Éditions scientifiques et médicales Elsevier SAS. All rights reserved.
Multiple magnetic transitions and the magnetocaloric effect in Gd1−xSmxMn2Ge2 compounds
Journal of Physics-condensed Matter, 2007
Magnetic and magnetocaloric properties of polycrystalline samples of Gd1-xSmxMn2Ge2 have been studied. All the compounds except GdMn2Ge2 show re-entrant ferromagnetic behavior. Multiple magnetic transitions observed in these compounds are explained on the basis of the temperature dependences of the exchange strengths of the rare earth and Mn sublattices. Magnetocaloric effect is found to be positive at the re-entrant ferromagnetic transition, whereas it is negative at the antiferro-ferromagnetic transition. In SmMn2Ge2, the magnetic entropy change associated with the re-entrant transition is found to decrease with field, which is attributed to the admixture effect of the crystal field levels. The isothermal magnetic entropy change is found to decrease with increase in Sm concentration.
Structure and magnetic properties of Gd4(Mn0.05Sb0.95)3
Physica B: Condensed Matter, 2003
This work studies the structure and magnetic properties of Gd 4 (Mn 0.05 Sb 0.95 ) 3 with the aim to clarify the role played by the magnetic Mn atom. Upon substitution of Mn for Sb in the parent Gd 4 Sb 3 compound, it is found that the inverted Th 3 P 4 -like structure has been somewhat expanded. The Curie temperature is increased while magnetic moment, measured in the field of 50 kOe at 200 K, is slightly reduced. The ferromagnetic semiconductor, Gd 4 (Mn 0.05 Sb 0.95 ) 3 , undergoes a ferromagnetic to paramagnetic transition at 270 K. Observed anomalies occur in the magnetization vs. temperature curves measured in a very low magnetic field. They are attributed to magnetic inhomogeneities resulting from a structural modification in Gd 4 (Mn 0.05 Sb 0.95 ) 3 . r 2002 Elsevier Science B.V. All rights reserved. PACS: 75.50.Pp; 75.30.Cr Keywords: Gd 4 (Mn 0.05 Sb 0.95 ) 3 ; Structure; Inhomogeneity; Magnetic phase transition 0921-4526/03/$ -see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 1 -4 5 2 6 ( 0 2 ) 0 1 7 7 5 -1
Journal of Alloys and Compounds, 2009
In this paper, we present crystal structure, electronic structure and magnetic properties of pollicrystalline Gd(Ni 1−x Fe x ) 3 intermetallic compounds. The rhombohedral PuNi 3 type of crystal structure for the whole series was confirmed with the use of X-ray powder diffraction. The partial replacement of Ni by Fe atoms up to x ≤ 0.4 causes the increase in Curie temperature T C and next for 0.4 < x ≤ 1 a slow decrease in T C value. As it was also shown saturation magnetization of the examined samples monotonically decreases with increasing Ni/Fe substitution. The magnetocaloric effect (MCE) for several samples with T C values around the room temperature was estimated from magnetic isotherms. The decrease in magnetic entropy connected with the increase in magnetic disorder in 3d magnetic sublattice has been observed. Moreover some correlations between magnetic properties and electronic structure studied by X-ray photoemission spectroscopy (XPS) have been found.
Magnetic properties and 155Gd M�ssbauer spectroscopy of LT-GdNiIn 2
Solid State Sci, 2006
A polycrystalline, single phase sample of the low-temperature (LT) modification of GdNiIn 2 (MgCuAl 2 type, Cmcm, a=434.5(1), b=1047.6(3), c=731.8(2) pm) was synthesized by arc-melting of the elements and subsequent annealing of the sample at 870 K. The magnetic properties of this compound were studied thoroughly by AC and DC magnetic susceptibility measurements and 155Gd Mössbauer spectroscopy. These results reveal four phase transitions: from a para- to a ferromagnetic state at T=60.5(5) and three other transitions at T=19.4(2) K, T=12.2(2) K, and T=4.0(2) K, respectively, which can be tentatively described as spin-reorientation transitions. LT-GdNiIn 2 shows strong thermal irreversibility between zero field cooled (ZFC) and field cooled (FC) DC magnetization.
The Mg-Rich Phase NdNiMg15: Structural and Magnetic Properties
Inorganic Chemistry, 2018
The intermetallic NdNiMg15 is the Mg-richest phase (more than 88 at% of Mg) discovered in the Mg-Nd-Ni system. Its structure was determined by X-ray diffraction on single-crystal with the following crystal data: tetragonal system, P4/nmm, Z = 2, a = 10.0602(1) Å, c = 7.7612(2) Å, dcalc = 2.40 g.cm-3. Its structure is made of a 3-Dimensional framework of magnesium atoms showing channels filled by 1D chain consisting of alternating Nd and Ni atoms along the c-axis. Antiferromagnetic ordering was observed with TN = 9K, which is remarkably high considering the long distances between magnetic atoms, i.e Nd atoms. The effective magnetic moment eff is equal to 3.58 µB which is consistent with magnetic Nd 3+ ions and weakly or non-magnetic Ni-atoms. Below TN, the M(H) curves show field induced metamagnetic transitions at critical fields increasing with decreasing temperatures. The magnetic structure of NdNiMg15 was determined from neutron powder diffraction data by considering the propagation vector k = (½ ½ 0). This magnetic structure consists in ferromagnetic chains along the c-axis of Nd atoms carrying moments, only separated by Ni atoms. The chains are ferromagnetically coupled within planes perpendicular to the [110] direction and these planes are antiferromagnetically coupled to neighboring planes forming a checkerboard-like magnetic structure.
Magnetic properties of Gd1−xCexMn2Ge2 compounds
Solid State Communications, 2001
The crystal structure and magnetic properties of polycrystalline Gd 12x Ce x Mn 2 Ge 2 (x 0:0 2 1:0) compounds with the ThCr 2 Si 2 -type structure have been investigated and the magnetic phase diagram has been constructed. The ferromagnetism observed in CeMn 2 Ge 2 transforms to ferrimagnetism with the substitution of Gd for Ce. An additional high temperature ferromagnetic phase in GdMn 2 Ge 2 weakens and eventually disappears with the addition of Ce. The saturation magnetization with increasing x at 4.2 K decreases up to the x 0:5, and then increases again. q
X-ray photoelectron spectroscopy and magnetism of Gd3Ni8Al
Journal of Alloys and Compounds, 2002
X-ray photoelectron spectroscopy (XPS), magnetization and magnetic susceptibility of Gd Ni Al are reported. Both valence band and 3 8 core level spectra were analyzed. Ni atoms have no magnetic moment because of charge transfer of Gd conduction electrons to the 3d band. This effect is mainly related with the 6s electrons of Gd. The filling of the Ni 3d band is revealed by the density of states at the Fermi level, the chemical shifts of Gd and Ni core levels and the value of the effective magnetic moment in the paramagnetic state. The compound Gd Ni Al exhibits a collinear ferromagnetic arrangement of Gd moments below the Curie temperature T 561 K. A negative 3 8 C 3d band polarization of 0.15 m / Ni is induced by the exchange interactions with the Gd spins. © 2002 Elsevier Science B. V. All rights B reserved. (M. Coldea).