Multiferroic phase diagram of E -type RMnO3 films studied by neutron and x-ray diffraction

Abstract

We present a generalized multiferroic phase diagram for orthorhombic RMnO 3 (R = Gd-Lu) based on coherently grown thin films. The magnetic order was identified by neutron-diffraction and resonant soft x-ray scattering experiments. For large R-ions (R = Gd-Dy), the transition temperature to a long-range ordered antiferromagnetic phase is only weakly dependent on the R-ion radius, but decreases monotonically with decreasing R-ion radius for films with R = Ho-Lu. The antiferromagnetic phase is characterized by an incommensurate order of the Mn 3+ spins, which successively locks into a commensurate E-type state. These findings confirm a uniform multiferroic ground state independent of the R ion and are in excellent agreement with predicted properties of strain-induced multiferroicity in these materials. In particular, strong variation of multiferroic properties in these epitaxial films compared to bulk highlights the tuning ability of strain.

Unique coexistence of incommensurate and commensurate magnetic order in TbMnO3 strained films

“…The sample was mounted in a He-flow cryostat with the (00l ) − (0k0) crystal axis in the horizontal scattering plane. This geometry gives access to the strongest magnetic peaks (0 q 1) and (0 1 + q 1) for the ICM and CM magnetic order as observed for similar films [9].…”

“…Recently, it was reported that o − RMnO 3 when grown as thin epitaxially strained films show unique changes in multiferroic properties [5,6,9]. At low temperatures the magnetic ground state is characterized by a CM E-type and a large ferroelectric polarization along the a-axis independent of the R-ion radii.…”

“…This enhancement is predicted to be responsible for stabilizing the E-type ground state in RMnO 3 [5,6]. In addition and unlike in bulk, a unique high temperature ICM magnetic phase with ferroelectric order was observed below T N ∼ 41 K in the coherently grown thin films [9]. At present, a detailed understanding of this ferroelectric ICM phase is still lacking.…”

Strain-induced robust magnetic anisotropy and room temperature magnetoelectric coupling effect in epitaxial SmFeO3 film

“…In order to explain the origin of the magnetically induced ferroelectricity, a large number of theoretical models were proposed one after another, such as reverse Dzyaloshinskii-Moriya (D-M) interaction [12], spin-dependent p-d hybridization and exchange striction mechanism [13,14]. So far, numerous single-phase multiferroic materials have been found, such as (Y, Sr, Gd, Dy, Tb, Ho, Lu)MnO 3 films [15][16][17][18], (Dy, Gd, Tb, Ho, Er, Lu)CrO 3 films [19][20][21][22][23], (Gd, Dy, Yb)FeO 3 films [24][25][26], EuTiO 3 films [27], hexaferrite Ba 2−x Sr x Mg 2 Fe 12 O 22 single crystal [28], and LaFeO 3 polycrystal [29]. Despite rich characteristics and fascinating physics, the low working temperature and weak saturation magnetization (M s ) restrict the practical applications of these materials.…”

Orthorhombic GdMnO3 Epitaxial Thin Film Grown onto SrTiO3 (110)

“…The interplay between structure and magnetism can be changed using structural distortions. Here we highlight that ferroelectricity was achieved below 30 and 75 K on orthorhombic GMO thin-films with 10 and 110 nm, deposited by pulsed laser deposition onto (010)-YAlO3 and (001)-SrTiO3 substrates, respectively [9,10]. Recently, the study of epitaxially strained GMO thin-films deposited on (001)-SrTiO3 substrate by RF magnetron sputtering, conveyed an unprecedently reported tetragonal structure at room temperature and ferroelectric below 32 K, up to 35 nm thick films [11].…”