Multiferroicity in doped hexagonalLuFeO3

Abstract

The hexagonal phase of LuFeO 3 is a rare example of a multiferroic material possessing a weak ferromagnetic moment, which is predicted to be switchable by an electric field. We stabilize this structure in bulk form though Mn and Sc doping, and determine the complete magnetic and crystallographic structures using neutron-scattering and magnetometry techniques. The ferroelectric P 6 3 cm space group is found to be stable over a wide concentration range, ordering antiferromagnetically with Néel temperatures that smoothly increase following the ratio of c to a (c/a) lattice parameters up to 172 K, the highest found in this class of materials to date. The magnetic structure for a range of temperatures and dopings is consistent with recent studies of high quality epitaxial films of pure hexagonal LuFeO 3 including a ferromagnetic moment parallel to the ferroelectric axis. We propose a mechanism by which room-temperature multiferroicity could be achieved in this class of materials.

Vortex ferroelectric domains, large-loop weak ferromagnetic domains, and their decoupling in hexagonal (Lu, Sc)FeO3

“…Even though the exact T N is still under debate, the presence of net ferromagnetic moment along the c axis is evident below 160-170 K. The magnetic state below 160-170 K is confirmed in both theory and experiment to be the A 2 -dominant spin configuration (Fig. 1b), 10,15 which results in a significant cantedantiferromagnetic (or WFM) moment along the c axis. Both large spontaneous P and M do coexist below 160-170 K. More importantly, a theoretical study predicts the presence of a bulk linear ME coupling or even the direct coupling between polarization and WFM domains in h-LuFeO 3 (ref.…”

“…A smooth reduction of magnetic susceptibility below 75 K upon cooling may indicate the presence of a spin reorientation transition away from the A 2 spin order, which has been reported in Lu 0.5 Sc 0.5 FeO 3 (ref. 15). This behavior is also evident in the M-H curves at 5 K and 130 K (Fig.…”

“…1a) has attracted a significant research attentions, since this metastable hexagonal phase of its orthorhombic bulk form was reported to be stabilized in thin film form by epitaxial strain 12,13 or in bulk by Sc or Mn doping. [14][15][16] Samples in both forms are believed to show similar physical properties despite different approaches used for the synthesis (see Supplementary Information, note 1 for details). They exhibit robust FE well above room temperature, similar to the wellstudied multiferroic hexagonal RMnO 3 (h-RMnO 3 , R= rare earth).…”

Spin-lattice coupling and frustrated magnetism in Fe-doped hexagonal LuMnO 3

“…This excludes Γ 3 (P 6 3 cm ), Γ 4 (P 6 3 c m) and Γ 6 (P 6 3 ) structures [9]. Hence it can be concluded from the observation of significant atomic displacements in the magnetic phase, that the magnetic structure of LuFe 0.5 Mn 0.5 O 3 must be Γ 1 below 112 K. In a recent report, Disseler et al, studied the magnetic structure of LuFe 0.75 Mn 0.25 O 3 [28]. They observed a T N ≈ 134 K and the presence of scattering intensity at (100) and (101) reflections above the T N suggesting that correlations related to both Γ 1 and Γ 2 were present.…”

Visualizing weak ferromagnetic domains in multiferroic hexagonal ferrite thin film

“…There are two effective routes to stabilize hexagonal polymorph of LuFeO 3 . One route is chemical doping of either Mn onto the Fe site or Sc onto the Lu site in bulk crystals [32][33][34][35] . The other is the epitaxial growth of thin films of the metastable phase on substrates with trigonal symmetry 36 .…”