Magnetic resonance of lanthanide ions as magnetic probes in the antiferromagnetic phase of dysprosium phosphate

1991 ◽  
Vol 435 (1895) ◽  
pp. 605-614 ◽  
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Moments ◽  
Internal Field ◽  
Host Lattice ◽  
Lanthanide Ions ◽  
Exchange Field ◽  
Impurity Ions ◽  
Isotropic Exchange ◽  
Impurity Ion ◽  
Magnetic Probes

Measurements of electron magnetic resonance are discussed for impurity ions in the antiferromagnetic host compound DyPO 4 (Néel temperature T N = 3.39 K). This is a simple two sublattice antiferromagnet; the impurity ions are Yb 3+ and Er 3+ , each with a Kramers doublet as the ground state. Resonance is observed at frequencies of ca . 24 and 34 GHz, and the angular dependence of the magnetic field is fitted to simple theoretical equations. Since the magnetic moments in the host lattice are ordered, the resonance lines are relatively narrow, making it possible to determine the value of the internal field acting on each impurity ion. From this, the exchange field is obtained by subtracting the value of the dipolar field generated by the ordered moments of the host ions. Some measurements have been made in the spin flop phase. The values of the exchange field are found not to conform to a simple model based on isotropic exchange interaction between the real electron spins of the lanthanide ions. Hyperfine splitting is detected from the odd isotope 171 Yb, natural abundance 14%, I = ½.

Electron spin resonance of paramagnetic impurities in antiferromagnetic compounds

1991 ◽  
Vol 433 (1888) ◽  
pp. 461-468 ◽  
Keyword(s):  
Internal Field ◽  
Host Lattice ◽  
Nuclear Resonance ◽  
Dipolar Field ◽  
Exchange Field ◽  
Paramagnetic Impurities ◽  
Resonance Frequencies ◽  
Spin Resonance ◽  
Impurity Ions ◽  
Impurity Ion

The possibility of magnetic resonance measurements on an impurity in an antiferromagnetic host lattice is discussed. The ion is subject to an internal field B int ; consisting of B dip , the dipolar field generated by the antiferromagnetic moments of the host ions, that can be calculated, and an exchange field B E . For a simple two sublattice antiferromagnet, two resonance frequencies should be observed; equations for their angular dependence are given, including the effect of hyperfine interaction. Impurity ions with Kramers doublets are discussed, together with ions with singlet ground states, for which enhanced nuclear resonance should be possible. A number of simple antiferromagnetic compounds of lanthanide (4f) ions that order at liquid helium temperatures are mentioned briefly, but for simplicity, the discussion is concentrated on GdVO 4 as the host lattice. A formula, based on the known exchange field in the host lattice, is deduced for its effect on the impurity ion.

A study of the host lattice effect in the lanthanide hydroxides. 34 GHz Gd3+ impurity ion EPR spectra at 77 and 294 K

1982 ◽  
Vol 60 (11) ◽  
pp. 1573-1588 ◽  
Author(s):  
V. M. Malhotra ◽  
H. A. Buckmaster
Keyword(s):  
Point Charge ◽  
Ionic Radius ◽  
Host Lattice ◽  
Epr Spectra ◽  
Zero Field ◽  
Nearest Neighbour ◽  
Zero Field Splitting ◽  
Impurity Ions ◽  
Lattice Effect ◽  
Impurity Ion

The 34 GHz EPR spectra of 5-state (4f7, 8S) Gd3+ impurity ions (~1%) in the isostructural [Formula: see text] symmetry Ln(OH)3 host lattice (Ln ≡ La, Sm, Eu, Tb, Ho, Y) have been studied at 77 and 294 K. The expected seven line ΔM = ± 1 spectrum is observed for Ln = La, Eu, Ho, and Y whereas only a single broad transition is observed for Ln ≡ Sm and Tb. The observed values of the zero field splitting (ZFS) parameter B20 as well as the TZFS are found to be related linearly to (i) the ionic radius, (ii) the Ln–O1 distance, and (iii) the Ln–O2 distance where O1 and O2 are the nearest neighbour equatorial and apical oxygens. However, the slopes are opposite to that predicted by a point charge lattice model. This paper discusses (i) the SH parameters, (ii) the host lattice effect, (iii) the ZFS processes, and (iv) the linewidths observed in the Ln(OH)3 host lattice and attempts to explain the observations using the existing theory. It is found that this apparently simple host lattice exhibits complex effects which do not change systematically with the host lanthanide ion, unlike that observed in most other isostructural lanthanide hosts that have been studied using Gd3+ impurity ions.

Electron Spin Decoherence by Nuclei

2018 ◽  
Author(s):  
M. M. Glazov
Keyword(s):  
Electron Spin ◽  
Spin Dynamics ◽  
Magnetic Moments ◽  
Host Lattice ◽  
Spin Model ◽  
Relaxation Processes ◽  
Nuclear Spins ◽  
Model Calculations ◽  
Spin Decoherence ◽  
Quantum Mechanical Approach

The discussion of the electron spin decoherence and relaxation phenomena via the hyperfine interaction with host lattice spins is presented here. The spin relaxation processes processes limit the conservation time of spin states as well as the response time of the spin system to external perturbations. The central spin model, where the spin of charge carrier interacts with the bath of nuclear spins, is formulated. We also present different methods to calculate the spin dynamics within this model. Simple but physically transparent semiclassical treatment where the nuclear spins are considered as largely static classical magnetic moments is followed by more advanced quantum mechanical approach where the feedback of electron spin dynamics on the nuclei is taken into account. The chapter concludes with an overview of experimental data and its comparison with model calculations.

Single ion magnets as magnetic probes of internal field in microparticle array

2021 ◽  
pp. 110210
Author(s):  
E. Dvoretskaya ◽  
A. Palii ◽  
O. Koplak ◽  
R. Morgunov
Keyword(s):  
Internal Field ◽  
Magnetic Probes

Heterobimetallische 3d-4f-Komplexe mit Bis(1,2-dithiooxalato)nickelat(II) als planarem Brückenbaustein / Heterobimetallic 3d-4f-Complexes with Bis(1,2-dithiooxalato)nickelate(II) as Planar Bridging Block

2005 ◽  
Vol 60 (11) ◽  
pp. 1149-1157 ◽  
Author(s):  
Matthias Siebold ◽  
Alexandra Kelling ◽  
Uwe Schilde ◽  
Peter Strauch
Keyword(s):  
Room Temperature ◽  
Magnetic Moments ◽  
Lanthanide Ions ◽  
Water Molecules ◽  
Unit Cell Parameters ◽  
Ionic Radii ◽  
X Ray ◽  
Cell Parameters ◽  
Heterobimetallic Complexes ◽  
The Individual

Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)n}2- {Ni(dto)2}3]・xH2O (Ln = Y3+, La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+; n = 4 or 5; x = 9 - 12). With [{Nd(H2O)5}2{Ni(S2C2O2)2}3]・xH2O (x = 10 - 12) (1) and [{Er(H2O)4}2{Ni(S2C2O2)2}3]・xH2O (x = 9 - 10) (2) we were able to isolate two complexes of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallize in two different crystal systems with the following unit cell parameters: 1, monoclinic in P21/c with a = 11.3987(13), b = 11.4878(8), c = 20.823(2) Å , β = 98.907(9)° and Z = 2; 2, triclinic in P1̅ with a = 10.5091(6), b = 11.0604(6), c = 11.2823(6) Å , α = 107.899(4)°, β = 91.436(4)°, γ = 112.918(4)° and Z = 1. The channels and cavities appearing in the packing of the molecules are occupied by uncoordinated water molecules. High magnetic moments up to 14.65 BM./f.u. have been observed at room temperature due to the combined moments of the individual lanthanide ions.

Magnetic moments of hindered rotators by off-center impurity ions

2002 ◽  
Vol 89 (4) ◽  
pp. 371-376
Author(s):  
A.G. Andreev ◽  
M. Georgiev ◽  
M.S. Mladenova ◽  
V. Krastev
Keyword(s):  
Magnetic Moments ◽  
Impurity Ions

39K, 40K and 41K Nuclear Magnetic Resonance Studies

1974 ◽  
Vol 29 (12) ◽  
pp. 1754-1762 ◽  
Author(s):  
W. Sahm ◽  
A. Schwenk
Keyword(s):  
Magnetic Resonance ◽  
Magnetic Moments ◽  
Relaxation Times ◽  
Isotopic Effect ◽  
Water Molecules ◽  
Potassium Salts ◽  
Rare Isotope ◽  
Resonance Frequencies ◽  
First Time ◽  
Limits Of Error

The NMR lines of 39K and 41K have been investigated in solutions of many potassium salts in H2O, D2O, methanol and ethylenediamine and also in solid potassium halides. The NMR signal of the rare isotope 40K was detected for the first time. The ratio of the Larmor frequencies of 39K and 41K has been measured in various samples: υ(30K)/υ(41K) =1.821873 1 (9). No primary isotopic effect was to be detected within these limits of error (0.5 ppm). The concentration dependence of the chemical shift of the 39K resonance frequencies was determined. Using this dependence, the ratios of the Larmor frequencies of the nuclei 39K, 40K, and 41K for infinite dilution relative to the resonance frequency of 2H in D2O are given. The magnetic moments of the 39K+, 40K+, and 41K+ ions purely surrounded by water molecules are μ(39K+) =0.390 952 9 (24)μN, μ(40K+) = -1.296 262(9)μN , μ(41K+) =0.214 588 4 (13) μN without diamagnetic corrections. Comparison of these values with the results of atomic beam magnetic resonance experiments yields the hyperfine structure anomalies of all pairs of potassium isotopes and also the shielding of potassium nuclei by water molecules around the ions; the shielding constant is σ* (K+ in H2O vs. K atom) = - 0.000 105 2(8). For the liquid samples the relaxation times T2 and for the solid ones the relaxation times T2 and the line widths are given.

Elecrically Detected Magnetic Resonance in A-SI:H Pin Cells

1993 ◽  
Vol 297 ◽  
Author(s):  
Klaus Lips ◽  
Walther Fuhs
Keyword(s):  
Solar Cells ◽  
Magnetic Resonance ◽  
Dark Current ◽  
Defect Density ◽  
Light Exposure ◽  
Forward Bias ◽  
Internal Field ◽  
Exciting Light ◽  
Applied Bias ◽  
Forward Current

We report on a detailed study of EDMR in pin-type solar cells. Like in films the signals are dominated by the contribution of the e-db resonance. It is found that the spectra depend on the applied bias and photon energy of the exciting light. The data suggest that the dark current is controlled by recombination in the bulk of the i-layer. The sign of the signal depends sensitively on the sign of the internal field. At high forward bias and illumination recombination at the pi-interface plays an important role. Degradation by both light exposure and high forward current results predominantly from an increase of the bulk defect density.

Complexes of Light Lanthanides with 3,4-Dimethoxybenzoic Acid

2000 ◽  
Vol 65 (2) ◽  
pp. 179-191 ◽  
Author(s):  
Wiesława Ferenc ◽  
Agnieszka Walków-Dziewulska
Keyword(s):  
Magnetic Moments ◽  
Intermediate Formation ◽  
Lanthanide Ions ◽  
Ligand Field ◽  
X Ray Diffraction ◽  
Magnetic Studies ◽  
X Ray ◽  
Light Lanthanides ◽  
Polycrystalline Solids ◽  
Van Vleck

The complexes of light lanthanides with 3,4-dimethoxybenzoic acid, Ln(C9H9O4)3·4 H2O, where Ln = La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III), have been synthesized as polycrystalline solids and characterized by elemental analysis, IR spectroscopy, thermogravimetric and magnetic studies and X-ray diffraction measurements. The complexes possess colours typical of Ln(III) ions (La, Ce, Eu, Gd white, Pr greenish, Nd violet and Sm cream). The carboxylate group in these complexes binds as a symmetrical, bidentate chelating ligand. On heating in air to 1 273 K the 3,4-dimethoxybenzoates of Ce(III), Pr(III), Sm(III), Eu(III) and Gd(III) first dehydrate to anhydrous salts that further decompose to oxides of the respective metals. The 3,4-dimethoxybenzoates of La(III) and Nd(III) decompose in three steps. Firstly, they dehydrate to anhydrous salts that further decompose to the oxides with the intermediate formation of oxycarbonates. The solubilities of the studied complexes in water at 293 K is in the order of 10-4-10-3 mol dm-3. Their magnetic moments were determined in the temperature range 77-298 K and found to obey the Curie-Weiss law. The values of μeff calculated for the all compounds (except that for Eu) are close to those obtained for Ln(III) by Hund and van Vleck. The results show that there is no influence of the ligand field on 4f electrons of the lanthanide ions in these polycrystalline compounds; 4f electrons probably do not participate in the formation of the Ln-O bonds.

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