Exchange Narrowing in the ESR Spectra of Metallic Gd_xLa₁–_xB₆ (x = 1 to 0.01)

Abstract

Linewidth measurements are reported of the ESR spectra of metallic Gd,Lal PIBE compounds (z = 1.0 to 0.01). This system is remarkable because contributions from the exchange narrowed linewidth 4 H e x and the homogeneous linewidth AHhom can be estimated. The interpretation of 4 H e x leads to values for the "exchange fields" H e as a function of the Gd concentration.Es wird uber Messungen der Linienbreiten im ESR-Spektrum metallivcher Gd,Lal-,BE-Verbindungen (z = 1.0 bis 0,Ol) berichtet. Dieses System ist insofern bemerkenswert, als die Beitrage der austauschverschmalerten Linienbreite AHex und der homogenen Linienbreite b f f h o m abgeschatzt werden konnen. Die Interpretation von AH,, fiihrt zu den Werten fur das .,Austauschfeld" H e als Funktion der Gd-Konzentration.

Tuning of exchange by band filling in low-carrier-density magnet Eu(Gd)B6

“…d show that J sf decreases drastically under the increase of Gd content falling from J sf ∼ 110 meV for x = 0 down to J sf ∼ 40 meV for x = 0.039. Note especially that the value of J sf ≈ 0.11 eV for EuB 6 agrees well with J sf = 0.08 eV extracted from resonant inelastic X‐ray scattering data , while J sf = 43 ± 1 meV for x = 0.03 and x = 0.039 coincides with the exchange integral J sf ≈ 45 meV ( J sf = 50 ± 10 meV) estimated for related metallic systems Gd x La 1− x B 6 (GdB 6 ) from ESR spectra. The good correlation in the J sf values obtained by different methods proves independently the validity of our approach.…”

“…c with the reference data for the La 1− x Gd x B 6 solid solutions shows that the low values of b ( x ) ≤ 1 Oe/K (range II, Fig. c) agree reasonably with these ones for typical bottleneck behavior while the slopes of 18–25 Oe/K in the range I are specific for the non‐bottleneck limit . This observation allows to apply the general relation for the Korringa slope b to extract the effective on‐site exchange J sf .…”

“…If the relaxation of the electrons to the lattice is slower than the fast Overhauser relaxation rate proportional to the density of S ‐state ions, backscattering of the excitation from the band electrons to the Eu 2+ spins inhibits the line broadening reducing strongly Korringa slope . This “bottleneck” effect was earlier found in the ESR study of La 1− x Gd x B 6 compounds for x ≥ 0.02 .…”

Quasi-one-dimensional spin chains in CuSiO3: an EPR study

“…Measurements of the specific heat give strong evidence for long-range antiferromagnetic order [11]. From the critical behavior of the linewidth it is not possible to compare CuSiO 3 unambiguously with typical antiferromagnets neither for the 1-D case like CuC12 9 2NCsH 5 (~z = 0.5 [15]) nor for the 3-D case like GdB 6 (o~ = 1.5 [16]). …”

Competing magnetic interactions in (Dy0.375Y0.625)2Cu2O5 solid solution studied by EPR

“…The data is reasonable well fitted by the power low dependence over a wide temperature range (13 K < T < 60 K) with T N = 11 K, but with two different values of the critical exponent p. In the higher temperature range (T > 30 K) p = 0.376(7), in a low temperature range (T < 20 K) p = 0.349 (7). The obtained values of critical exponent p reflect the low-dimensional character of the EPR line when it is compared with the critical behavior of linewidth of typical antiferromagnets in the 1D case, such as CuCl 2 · 2HC 5 H 5 (p = 0.5) [23], or in the 3D case, such as GdB 6 (p = 1.5) [24]. On the other hand, the observed change of value of the critical exponent p could be associated with dimensional crossover that the magnetic system undergoes in that temperature range.…”