Site percolation and a spin-diffusion model as applied to Gd3+EPR linewidth behaviour in PrxLa1-xF3single crystals

Misra, Sushil K.; Orhun, Ufuk

doi:10.1088/0953-8984/4/30/012

Cited by 4 publications

(3 citation statements)

References 8 publications

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“…A number of Zn atoms substituted by Cu introduces a magnetic moment that increases not only the crystal distortion but also the magnetic interactions. Here, a phase separation landscape due to the chemical inhomogeneous substitution on the A site is proposed for the ZCCO series by a schematic site percolation model [45][46][47][48][49][50][51][52]. Assuming that a low concentration of Cu 2+ ions occupies the A sites in the ZnCr 2 O 4 crystal lattices, there is an Asite disorder with the appearance of small Cu 2+ -rich clusters and a chemical phase separation emerges.…”

Section: Discussionmentioning

confidence: 99%

Glassy magnetic behavior induced by Cu²⁺substitution in the frustrated antiferromagnet ZnCr₂O₄

Maciá

Jiang

et al. 2008

J. Phys.: Condens. Matter

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Structure and magnetic properties of the compounds Zn1−xCuxCr2O4 (ZCCO) are investigated systematically. A structural phase transition from space-group symmetry F d3m to I41/amd is observed in ZCCO. The critical value of the doping, x, appears at 0.58 ∼ 0.62 through the appearance of a splitting of diffraction peaks at room temperature. Measurements of dc magnetization, ac susceptibility, memory effect and exchange bias-like (EB-like) effect have been performed to reveal the glassy magnetic behaviors of ZCCO. The system with x 0.50 is suggested as a spin glass-like (SG-like) of magnetic characterization whereas doping values of 0.58 x 0.90 defines the system as a "cluster glass-like" (CG-like) with unidirectional anisotropy. The Cu content suppresses the geometrical frustration of ZnCr2O4, which may correlate with the pinning effect of Cu sublattice on Cr sublattice to a preferential direction.

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Section: Discussionmentioning

confidence: 99%

Glassy magnetic behavior induced by Cu²⁺substitution in the frustrated antiferromagnet ZnCr₂O₄

Maciá

Jiang

et al. 2008

J. Phys.: Condens. Matter

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“…[8][9][10][11][12][13] An optical study of the mixed rare-earth crystals, such as Y x Lu 1Ϫx F 3 , Yb x Y 1Ϫx F 3 , Yb x Gd 1Ϫx F 3 , revealed the importance of disorder as deduced from spectral linewidths of the impurity ion Er 3ϩ . 14 Theoretical studies on EPR linewidth behavior in mixed magnetically dilute rare-earth crystals have been reported recently by Misiak, Misra, and Mikolajczak, 15 and by Misiak, Misra, and Orhun 16 on LiYb x Y 1Ϫx F x single crystals, and by Misra and Orhun 17 on Pr x La 1Ϫx F 3 single crystals. Percolation-cluster model was applied by Misra and Orhun 18 to explain the behavior of Gd 3ϩ EPR linewidths in LiYb x Y 1Ϫx F 4 , according to which, a percolation cluster extends across the sample broadening the EPR lines sharply as a result of shortened spinlattice relaxation times when the concentration of the paramagnetic ions exceeds a certain critical value.…”

Section: Introductionmentioning

confidence: 93%

Effect of host paramagnetic ions on theGd3+EPR linewidth in diluted Van-Vleck paramagnetsTm
Misra
¹
,
Andronenko
²

1996
Phys. Rev. B
1
0
1
0
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Gd 3ϩ EPR linewidths in diluted Van-Vleck paramagnets Ho x Y 1Ϫx VO 4 (xϭ0.0, 0.02, 0. 05, 0.1, 0.15, 0.25, 0.3, 0.5, 0.9, 1.0) and Tm x Lu 1Ϫx PO 4 (xϭ0.0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0) were measured at X band ͑8.7-9.6 GHz͒ in the temperature range 4.2-300 K as functions of temperature and concentration (x) of the host paramagnetic ions, Ho 3ϩ and Tm 3ϩ , respectively. It was found that the dipole-dipole and exchange interactions significantly influenced the measured linewidths in Ho x Y 1Ϫx VO 4 and Tm x Lu 1Ϫx PO 4 samples for the concentrations xϾ0.1 and xϾ0.6, respectively. Further, in Ho x Y 1Ϫx VO 4 samples with xϾ0.3 the EPR lines disappeared at temperatures above 10 K due to the formation of percolation clusters by Ho 3ϩ ions; the disorder was deduced to have a negligible effect in these hosts. Interaction of the lattice with the electronic quadrupole moment of Ho 3ϩ ions created different structural sites of Gd 3ϩ in Ho x Y 1Ϫx VO 4 samples with xϾ0.1 depending on the number of Ho 3ϩ ions in the immediate neighborhood of a Gd 3ϩ ion, resulting in the observation of up to three different sets of Gd 3ϩ EPR spectra. As for Tm x Lu 1Ϫx PO 4 samples with 0.1ϽxϽ0.8, it was the disorder, rather than a percolation cluster, that dominated the Gd 3ϩ EPR linewidths due to the rather large difference in the ionic radii of Tm 3ϩ and Lu 3ϩ ions, as well as in the unit-cell parameters of TmPO 4 and LuPO 4 . The temperature variation of the linewidths were found to be in accordance with those of the average magnetic moments of Ho 3ϩ and Tm 3ϩ ions in Ho x Y 1Ϫx VO 4 and Tm x Lu 1x PO 4 , respectively. Gd 3ϩ spin-Hamiltonian parameters were estimated at different temperatures for the two families of hosts. EPR spectra of the Er 3ϩ ion, present as a chemical impurity, have also been observed in Ho x Y 1Ϫx VO 4 samples at liquid-helium temperatures.

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“…Misra et al [14][15][16] have studied the compounds PrxLal_xF3:Gd 3+ [14], LiYb~Yl_xF4:Gd 3+ [15], H%YI_xVO4:Er 3+ [16]. References 14 and 15 are devoted mainly to percolation of clusters, in ref.…”

Section: Introductionmentioning

confidence: 99%

EPR of Yb3+ ions in Ba1−xLaxF2+x mixed crystals

et al. 2005

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Electron paramagnetic resonance (EPR) spectra of impurity Yb 3 § ions (about 0.1 at.%) in mixed crystals BaF:(I -x) plus LaF3(x) have been investigated for different values of the concentration x at a frequency of about 9.5 GHz by both continuous-wave (CW) EPR and electron spin echo methods. A spectrum of trigonal symmetry with a complex hyperfine structure is observed in "pure" BaFz:Yb 3 § (x = 0). Upon admixture of small amounts of LaF3 (x = 0.001), additional EPR lines arise with intensities increasing with the increase of x up to 0.005. These lines are attributed to trigonal centers including two rare-earth ions and two compensating fluorine ions. A further increase of x results in a decrease of the total EPR spectrum intensity, andat x > 0.05 the CW resonance becomes practically unobservable. This may be due to the formation of rare-earth ion clusters with paramagnetic Yb 3. ions occurring in domains with a disordered structure of surroundings resulting in very broad EPR lines, which cannot be registered by CW EPR. Indeed, very broad (not less than 1 kG) EPR lines were observed by the electron spin echo method for concentrations x > 0.02.

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Site percolation and a spin-diffusion model as applied to Gd³⁺EPR linewidth behaviour in Pr_xLa_1-xF₃single crystals

Cited by 4 publications

References 8 publications

Glassy magnetic behavior induced by Cu²⁺substitution in the frustrated antiferromagnet ZnCr₂O₄

Glassy magnetic behavior induced by Cu²⁺substitution in the frustrated antiferromagnet ZnCr₂O₄

Effect of host paramagnetic ions on theGd3+EPR linewidth in diluted Van-Vleck paramagnetsTm
Misra
¹
,
Andronenko
²

1996
Phys. Rev. B
1
0
1
0
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EPR of Yb3+ ions in Ba1−xLaxF2+x mixed crystals

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Site percolation and a spin-diffusion model as applied to Gd3+EPR linewidth behaviour in PrxLa1-xF3single crystals

Cited by 4 publications

References 8 publications

Glassy magnetic behavior induced by Cu2+substitution in the frustrated antiferromagnet ZnCr2O4

Glassy magnetic behavior induced by Cu2+substitution in the frustrated antiferromagnet ZnCr2O4

Effect of host paramagnetic ions on theGd3+EPR linewidth in diluted Van-Vleck paramagnetsTmMisra1, Andronenko2 1996Phys. Rev. B1010View full textAdd to dashboardCite

EPR of Yb3+ ions in Ba1−xLaxF2+x mixed crystals

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Site percolation and a spin-diffusion model as applied to Gd³⁺EPR linewidth behaviour in Pr_xLa_1-xF₃single crystals

Glassy magnetic behavior induced by Cu²⁺substitution in the frustrated antiferromagnet ZnCr₂O₄

Glassy magnetic behavior induced by Cu²⁺substitution in the frustrated antiferromagnet ZnCr₂O₄

Effect of host paramagnetic ions on theGd3+EPR linewidth in diluted Van-Vleck paramagnetsTm
Misra
¹
,
Andronenko
²

1996
Phys. Rev. B
1
0
1
0
View full text Add to dashboard Cite