Spin-canting-induced improper ferroelectricity and spontaneous magnetization reversal in SmFeO3.
SmFeO3, a family of centrosymmetric rare-earth orthoferrites, is known to be nonferroelectric. However, we have found that SmFeO3 is surprisingly ferroelectric at room temperature with a small polarization along the b axis of Pbnm. First-principles calculations indicate that the canted antiferromagnetic ordering with two nonequivalent spin pairs is responsible for this extraordinary polarization and that the reverse Dzyaloshinskii-Moriya interaction dominates over the exchange-striction mechanism in the manifestation of the improper ferroelectricity. SmFeO3 further exhibits an interesting phenomenon of spontaneous magnetization reversal at cryogenic temperatures. This reversal is attributed to the activation of the Sm-spin moment which is antiparallel to the Fe-spin moment below ∼5  K.
Department of Materials Science and Engineering, and Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
Jung-Hoon
JH
Lee
Young Kyu
YK
Jeong
Jung Hwan
JH
Park
Min-Ae
MA
Oak
Hyun Myung
HM
Jang
Jong Yeog
JY
Son
James F
JF
Scott