Experimental evidence of noncollinear magnetism in gadolinium tetraboride (original) (raw)
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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...
Magnetism of rare earth tetraborides
Journal of Physics: Conference Series, 2010
The rare earth tetraborides REB4 with RE = Ho, Er, Tm, crystallize in a tetragonal lattice where the positions of the RE ions can be mapped to a Shastry Sutherland lattice. We have investigated the magnetic properties by means of magnetisation and specific heat experiments in a magnetic field. All compounds are anisotropic, with RE= Er, Tm they are strong Ising magnets, for RE = Ho we find xy anisotropy. In magnetic field we find complex behaviour with a number of different phases as a function of applied field, field direction and temperature. Remarkable is the observation of fractional magnetisation plateaux for magnetic field || (001) in HoB4 and TmB4.
Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound
Materials
We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δμ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (X...
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 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.
Physical Review B, 2005
Gd 5 Ge 4 crystallizes in the orthorhombic space group Pnma, and orders antiferromagnetically below the Néel temperature T N ϳ 127 K. We have employed x-ray resonant magnetic scattering to elucidate the details of the magnetic structure. The magnetic unit cell is the same as the chemical unit cell. From azimuth scans and the Q dependence of the magnetic scattering, all three Gd sites in the structure were determined to be in the same magnetic space group PnmЈa. The magnetic moments are primarily aligned along the c axis and the c components of the magnetic moments at the three different sites are equal. The ferromagnetic Gd-rich slabs are stacked antiferromagnetically along the b direction.
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.
Magnetostriction reveals orthorhombic distortion in tetragonal Gd compounds
Physical Review B, 2019
We report detailed thermal expansion and magnetostriction experiments on GdCoIn5 and GdRhIn5 single crystal samples that show a sudden change in the dilation at a field B for temperatures below the Néel transition temperature TN. We present a first-principles model including crystal-field effects, dipolar and exchange interactions, and the dependence of the exchange couplings with lattice distortions in order to fully account for the magnetostriction and magnetic susceptibility data. The mean-field solution of the model shows that a transition between metastable states occurs at the field B. It also indicates that two degenerate phases coexist in the sample at temperatures below TN. This allows to explain the lack of observation, in high resolution x-ray experiments, of an orthorhombic distortion at the Néel transition even though the magnetic structure breaks the tetragonal symmetry and the magnetoelastic coupling is significant. These conclusions could be extended to other tetragonal Gd-based compounds that present the same phenomenology.
Magnetic structure of GdB_ {4} from spherical neutron polarimetry
2006
Interest in the antiferromagnetic ordering on GdB 4 has been recently renewed by the observation of interference between magnetic and anisotropic charge contributions obtained from resonant x-ray scattering experiments at the Gd L 3 edge. Models accounting for the x-ray experiments with collinear and noncollinear Gd magnetic moments are almost indistinguishable from the experimental data available. However, the ambiguity between the different arrangements can be resolved directly and much more easily using spherical neutron polarimetry. The present findings show that the Gd moments order noncollinearly in a structure with the Shubnikov magnetic space group P4/mЈbЈmЈ, which has magnetoelectric symmetry.
Specific features of Eu 3+ and Tb 3+ magnetooptics in gadolinium-gallium garnet (Gd 3Ga 5O 12)
Journal of Rare Earths, 2011
We reported magnetooptical properties of Eu3+(4f(6)) and Tb3+(4f(8)) in single crystals of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG), and Eu3+(4f(6)) in Eu3Ga5O12 (EuGG) for both ions occupying sites of D2 symmetry in the garnet structure. Absorption, luminescence, and magnetic circular polarization of luminescence (MCPL) spectra of Tb3+ in GGG and YGG and absorption and magnetic circular dichroism (MCD) of Eu3+ in EuGG were studied. The data were obtained at 85 K and room temperature (RT). Magnetic susceptibility of Eu3+ in EuGG was also measured between 85 K and RT. The magnetooptical and magnetic susceptibility data were modeled using the wavefunctions of the crystal-field split energy (Stark) levels of Eu3+ and Tb3+ occupying D2 sites in the same garnets. The results reported gave a precise determination of these Stark level assignments and confirmed the symmetry labels (irreducible representations) of the closely-spaced Stark levels (quasi-doublets) found in the 5D1 (Eu3+) and 5D4 (Tb3+) multiplets. Ultraviolet (UV) excitation (<300 nm) of the 6PJ and 6IJ states of Gd3+ in the doped GGG crystals led to emission from 5D4 (Tb3+) and 5D1 and 5D0 (Eu3+) through radiationless energy transfer to the 4f(n−1)5d band of Tb3+ and to UV quintet states of Eu3+. The temperature-dependent emission line shapes and line shifts of the magnetooptical transitions excited by UV radiation suggested a novel way to explore energy transfer mechanisms in this rare-earth doped garnet system.