Field-induced polar order at the Néel temperature of chromium in rare-earth orthochromites: Interplay of rare-earth and Cr magnetism

We report field-induced switchable polarization (P ~ 0.2-0.8 mu C/cm super(2)) below the Neel temperature of chromium (T sub(N) super(Cr)) in weakly ferromagnetic rare-earth orthochromites, RCrO sub(3) (R = rare earth) but only when the rare-earth ion is magnetic. Intriguingly, the polarization in E...

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Bibliographic Details
Published in:Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2012-12, Vol.86 (21), Article 214409
Main Authors: Rajeswaran, B., Khomskii, D. I., Zvezdin, A. K., Rao, C. N. R., Sundaresan, A.
Format: Article
Language:English
Subjects:
Chromium
Condensed matter
Ferromagnetism
Ion exchangers
Magnetic fields
Neel temperature
Polarization
Rare earth metals
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Summary:We report field-induced switchable polarization (P ~ 0.2-0.8 mu C/cm super(2)) below the Neel temperature of chromium (T sub(N) super(Cr)) in weakly ferromagnetic rare-earth orthochromites, RCrO sub(3) (R = rare earth) but only when the rare-earth ion is magnetic. Intriguingly, the polarization in ErCrO sub(3) (T sub(C) = 133 K) disappears at a spin-reorientation (Morin) transition (T sub(SR) ~ 22 K) below which the weak ferromagnetism associated with the Cr sublattice also disappears, demonstrating the crucial role of weak ferromagnetism in inducing the polar order. Further, the polarization (P) is strongly influenced by an applied magnetic field, indicating a strong magnetoelectric effect. We suggest that the polar order occurs in RCrO sub(3), due to the combined effect of the poling field that breaks the symmetry and the exchange field on the R ion from the Cr sublattice that stabilizes the polar state. We propose that a similar mechanism could work in the isostructural rare-earth orthoferrites RFeO sub(3) as well.
ISSN:1098-0121
1550-235X
DOI:10.1103/PhysRevB.86.214409