DocumentCode
1330428
Title
Electron-Spin Resonance of a La
Sr
MnO
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 spectra of a La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> slab. Experimental results reveal that ESR spectra in the ferromagnetic (FM) region are followed with a broadly resonant mode as θ = 90<sup>°</sup>, but several modes as θ = 0<sup>°</sup>. Their spectral parameters depend strongly on θ. When keeping θ = 0<sup>°</sup> and measuring the temperature dependence of ESR spectra, it is found that several resonant modes in the FM region become a single mode in the Dysonian line-shape at temperatures <i>T</i> >; <i>T</i><sub>min</sub> ≈ 1.1 <i>TC</i>. At <i>T</i><sub>min</sub>, the spectral linewidth reaches to a minimum value of Δ<i>H</i><sub>min</sub>= 283 Oe. Temperature dependences of the EPR intensity above <i>T</i><sub>min</sub> obey a function <i>I</i>(<i>T</i>) = <i>Io</i> exp(<i>Ea</i>/ <i>kB T</i>). Having based on the relation of <i>I</i>(<i>T</i>) ∝ χ(<i>T</i>) = 1/(<i>T</i>-Θ) , we obtained the Curie-Weiss temperature Θ to be 376 K. If using a simple relation of <i>g</i> = <i>h</i>ν/ μ<i>B Hr</i> (<i>Hr</i> is the resonant position, and μ<i>B</i> is the Bohr magneton), we have found that the effective Lande factor <i>g</i> increases from 1.91 (around <i>T</i><sub>min</sub>) to ~ 1.98 (at 473 K) close to the value of <i>g</i> = 2.0 for spin-spin interactions of Mn ions. This could be due to the additional presence of magnetic interactions, besides spin-spin interactions, such as interactions between FM clusters and/or spin-orbital coupling. Interestingly, despite the sample in the PM regime, the spectral parameters depend on the angle θ. This is assigned to an anisotropic field related to Mn <sup>3+</sup>-Mn <sup>4 +</sup> FM clusters persisting above <i>T</i><sub>min</sub>. At 470 K, the anisotropy constant obtained is <i>Ku</i> ≈ 57 erg/cm <sup>3</sup>, much sm- - aller than that in the FM region.</div></div>
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<div class='row g-0 align-items-center mb-2'><div class='col-12 col-md-3 fullRecLabelEnglish fw-bold mb-2 mb-md-0'><span class='text-muted small'>Keywords</span></div><div class='col-12 col-md-9 leftDirection leftAlign'>colossal magnetoresistance; ferromagnetic-paramagnetic transitions; g-factor; lanthanum compounds; magnetic anisotropy; magnetic susceptibility; metal clusters; paramagnetic resonance; paramagnetism; resonant states; spin-orbit interactions; strontium compounds; Curie-Weiss temperature; Dysonian line-shape; EPR intensity; ESR spectra; La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub>; La<sub>0.7</sub>Sr<sub>0.3</sub>MnO<sub>3</sub> slab; Mn ions; Mn<sup>3+</sup>-Mn<sup>4 +</sup> FM clusters; anisotropic field; anisotropy constant; effective Lande factor; electron spin resonance; ferromagnetic region; magnetic interactions; resonant modes; spectral linewidth; spin-orbital coupling; spin-spin interactions; temperature 376 K; temperature 470 K; Frequency modulation; Magnetic anisotropy; Magnetic resonance; Strontium; Temperature; Temperature dependence; Temperature measurement; Perovskite manganite; electron-spin resonance (ESR);</div></div>
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<div class='row g-0 align-items-center mb-2'><div class='col-12 col-md-3 fullRecLabelEnglish fw-bold mb-2 mb-md-0'><span class='text-muted small'>Journal_Title</span></div><div class='col-12 col-md-9 leftDirection leftAlign'>Magnetics, IEEE Transactions on</div></div>
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<div class='row g-0 align-items-center mb-2'><div class='col-12 col-md-3 fullRecLabelEnglish fw-bold mb-2 mb-md-0'><span class='text-muted small'>ISSN</span></div><div class='col-12 col-md-9 leftDirection leftAlign'>0018-9464</div></div>
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<div class='row g-0 align-items-center mb-2'><div class='col-12 col-md-3 fullRecLabelEnglish fw-bold mb-2 mb-md-0'><span class='text-muted small'>DOI</span></div><div class='col-12 col-md-9 leftDirection leftAlign'>10.1109/TMAG.2011.2157102</div></div>
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