<p>We investigate the effect of Ce<sup>3+</sup> substitution on the magnetic ordering and phonon dynamics of the GdCrO<sub>3</sub> orthorhombic perovskite. The Ce doped compound exhibits long-range canted antiferromagnetism with Néel transitions, <i>T</i><sub>N</sub> at ~ 173&#xa0;K, accompanied by spin-flip, <i>T</i><sub>SF</sub> at ~ 10&#xa0;K. Ce<sup>3+</sup> incorporation drives a modification of the spin-flip transition from the <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\varGamma}_{4}\left({G}_{x},{A}_{y},{F}_{z}\right)\)</EquationSource> </InlineEquation>configuration to <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\varGamma}_{4}^{{\prime}}\)</EquationSource> </InlineEquation> inducing a reorientation of the spin axis between the <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(\left(00\stackrel{-}{1}\right)\)</EquationSource> </InlineEquation>and (001) crystallographic planes. This spin reorientation is governed by Zeeman energy and produces pronounced field-induced irreversibility between FCC and FCW magnetization processes. The substituted compound Gd<sub>0.9</sub>Ce<sub>0.1</sub>CrO<sub>3</sub> (GCCO) exhibits a remarkably large magnetic entropy change, <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(-\varDelta{S}_{M}\)</EquationSource> </InlineEquation> ~ 45 –40&#xa0;J/kg-K for ∆H = 90 − 70 kOe at 3&#xa0;K among the highest reported for rare-earth orthochromites. The interplay of spin-only magnetocrystalline anisotropy from Cr<sup>3+</sup> and spin–orbit–driven magnetic moments of Gd<sup>3+</sup> and Ce<sup>3+</sup> results in pronounced spin–phonon coupling, manifested through the A<sub>1g</sub>(6) vibrational mode. The observed temperature-dependent spectral evolution is consistent with behaviour reported in isostructural magnetic perovskites.&#xa0;</p>

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Giant-magnetocaloric effect and phonon dynamics in (GdCe)CrO3

  • Ravi Kiran Dokala,
  • Shaona Das,
  • Subhash Thota

摘要

We investigate the effect of Ce3+ substitution on the magnetic ordering and phonon dynamics of the GdCrO3 orthorhombic perovskite. The Ce doped compound exhibits long-range canted antiferromagnetism with Néel transitions, TN at ~ 173 K, accompanied by spin-flip, TSF at ~ 10 K. Ce3+ incorporation drives a modification of the spin-flip transition from the \({\varGamma}_{4}\left({G}_{x},{A}_{y},{F}_{z}\right)\) configuration to \({\varGamma}_{4}^{{\prime}}\) inducing a reorientation of the spin axis between the \(\left(00\stackrel{-}{1}\right)\) and (001) crystallographic planes. This spin reorientation is governed by Zeeman energy and produces pronounced field-induced irreversibility between FCC and FCW magnetization processes. The substituted compound Gd0.9Ce0.1CrO3 (GCCO) exhibits a remarkably large magnetic entropy change, \(-\varDelta{S}_{M}\) ~ 45 –40 J/kg-K for ∆H = 90 − 70 kOe at 3 K among the highest reported for rare-earth orthochromites. The interplay of spin-only magnetocrystalline anisotropy from Cr3+ and spin–orbit–driven magnetic moments of Gd3+ and Ce3+ results in pronounced spin–phonon coupling, manifested through the A1g(6) vibrational mode. The observed temperature-dependent spectral evolution is consistent with behaviour reported in isostructural magnetic perovskites.