title: Strain-induced effects on antiferromagnetic ordering and magnetocapacitance in orthorhombic HoMnO(3) thin films.
abstract: We investigated the magnetic and ferroelectric properties of c-axis oriented orthorhombic phase HoMnO(3) (o-HMO in Pbnm symmetry setting) thin films grown on Nb-doped SrTiO(3)(001) substrates. The o-HMO films exhibit an antiferromagnetic ordering near 42 K, irrespective of the orientation of the applied field. However, an additional magnetic ordering occurring around 35 K was observed when the field was applied along the c-axis of o-HMO, which was absent when the field was applied in the ab-plane. The magnetocapacitance measured along the c-axis showed that although there is evidence of dielectric constant enhancement when the temperature is below 35 K the expected abrupt change in dielectric constant appears at a much lower temperature and reaches maximum around 13.5 K, indicating that the low-temperature c-axis polarization might be related to the ordering of the Ho(3+) moment. The lattice constant analyses using x-ray diffraction and the observation of a slight magnetization hysteresis suggest that the weak second magnetic transition along the c-axis at 35 K might be more relevant to the strain-induced effect on antiferromagnetism.
authors.affiliation: Department of Electrophysics, National Chiao Tung University, Hsinchu 300, Taiwan.
authors.forename: T H
authors.initials: TH
authors.lastname: Lin
authors.forename: H C
authors.initials: HC
authors.lastname: Shih
authors.forename: C C
authors.initials: CC
authors.lastname: Hsieh
authors.forename: C W
authors.initials: CW
authors.lastname: Luo
authors.forename: J-Y
authors.initials: JY
authors.lastname: Lin
authors.forename: J L
authors.initials: JL
authors.lastname: Her
authors.forename: H D
authors.initials: HD
authors.lastname: Yang
authors.forename: C-H
authors.initials: CH
authors.lastname: Hsu
authors.forename: K H
authors.initials: KH
authors.lastname: Wu
authors.forename: T M
authors.initials: TM
authors.lastname: Uen
authors.forename: J Y
authors.initials: JY
authors.lastname: Juang