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![]() GNEZDILOV, Vladimir, LEMMENS, Peter, PASHKEVICH, Yurii, PAYEN, Christophe, CHOI, Kwang Yong, HEMBERGER, Joachim, LOIDL, Alois, TSURKAN, Vladimir. Phonon anomalies and possible local lattice distortions in giant magnetocapacitive CdCr2S4. In: Physical Review B - Condensed Matter and Materials Physics, 2011, vol. 84, p. 0. ISSN 1098-0121. DOI: https://doi.org/10.1103/PhysRevB.84.045106 |
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Physical Review B - Condensed Matter and Materials Physics | |
Volumul 84 / 2011 / ISSN 1098-0121 /ISSNe 1550-235X | |
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DOI:https://doi.org/10.1103/PhysRevB.84.045106 | |
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We investigate the origin of large magnetocapacitive effects in CdCr 2S4 single crystals focusing on phonon anomalies in the fluctuation regime T < T* = 130 K and with the onset of ferromagnetic order Tc = 84.4 K. The observation of longitudinal optical and formerly infrared active modes for T < Tc is used to propose a loss of inversion symmetry and Cr off-centering. Further anomalies in intensity, frequency, and linewidth have an onset temperature T* that coincides with the onset of magnetocapacitive effects. The respective intensity anomalies are attributed in part to an enhanced electronic polarizability of displacements that modulate the Cr-S distance and respective hybridization. This is taken as a prerequisite to the proposed Cr off-centering. Anomalies due to the previously disregarded photodoping and resonance are analyzed comparing different excitation energies. |
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Cuvinte-cheie magnetism, Curie Temperature, Antiferromagnet |
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