High Pressure Experimental Studies on CuO: Indication of Re-entrant Multiferroicity at Room Temperature

We have carried out detailed experimental investigations on polycrystalline CuO using dielectric constant, dc resistance, Raman spectroscopy and X-ray diffraction measurements at high pressures. Observation of anomalous changes both in dielectric constant and dielectric loss in the pressure range 3....

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Published inScientific reports Vol. 6; no. 1; p. 31610
Main Authors Jana, Rajesh, Saha, Pinku, Pareek, Vivek, Basu, Abhisek, Kapri, Sutanu, Bhattacharyya, Sayan, Mukherjee, Goutam Dev
Format Journal Article
LanguageEnglish
Published London Nature Publishing Group UK 17.08.2016
Nature Publishing Group
Subjects
140/133
639/301/119/996
639/766/119/996
Compression
Dielectric constant
Dielectric properties
High pressure
Humanities and Social Sciences
multidisciplinary
Pressure
Raman spectroscopy
Science
Science education
Spectroscopy
Spectrum analysis
Temperature effects
X-ray diffraction
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Summary:We have carried out detailed experimental investigations on polycrystalline CuO using dielectric constant, dc resistance, Raman spectroscopy and X-ray diffraction measurements at high pressures. Observation of anomalous changes both in dielectric constant and dielectric loss in the pressure range 3.7–4.4 GPa and reversal of piezoelectric current with reversal of poling field direction indicate to a change in ferroelectric order in CuO at high pressures. A sudden jump in Raman integrated intensity of A g mode at 3.4 GPa and observation of Curie-Weiss type behaviour in dielectric constant below 3.7 GPa lends credibility to above ferroelectric transition. A slope change in the linear behaviour of the A g mode and a minimum in the FWHM of the same indicate indirectly to a change in magnetic ordering. Since all the previous studies show a strong spin-lattice interaction in CuO, observed change in ferroic behaviour at high pressures can be related to a reentrant multiferroic ordering in the range 3.4 to 4.4 GPa, much earlier than predicted by theoretical studies. We argue that enhancement of spin frustration due to anisotropic compression that leads to change in internal lattice strain brings the multiferroic ordering to room temperature at high pressures.
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Present address: Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015-1305, USA.
ISSN:2045-2322
2045-2322
DOI:10.1038/srep31610