Novel multiferroicity in GdMnO3 thin films with self-assembled nano-twinned domains

Abstract

There have been many interests in exploring multiferroic materials with superior ferroelectric and magnetic properties for the purpose of developing multifunctional devices. Fabrication of thin films plays an important role in achieving this purpose, since the multiferroicity can be tuned via strain, dimensionality, and size effect, without varying the chemical composition. Here, we report exotic multiferroic behaviors, including high-TC (~75 K) ferroelectric state, a large spontaneous polarization (~4900 μC/m2) and relatively strong ferromagnetism emerging at ~105 K, in orthorhombic GdMnO3/SrTiO3 (001) thin films with self-assembled nano-scale twin-like domains. We propose a possible ab-plane spiral-spin-order phase to be responsible for the large spontaneous polarization in the films, which can only be stabilized by relatively high magnetic field H > 6 T in the bulk crystals. It is suggested that the nano-scale twin-like domain structure is essential for the high temperature ferroelectricity and ferromagnetism of the thin films.

Multiferroic oxide thin films and heterostructures

“…110 In DMO ( Figure 9) and GdMnO 3 thin films grown on SrTiO 3 (001), the ferroelectric polarization was clearly demonstrated by both pyroelectric current method and hysteresis measurement, and large magnetic anisotropy and magnetic field induced polarization enhancement were also identified. 111,112 In particular, large spontaneous polarization was reported in GdMnO 3 thin films, which is probably due to a self-assembled nano-twinned domain structure. 112 This result indicates that finely tuning the competing balance of multiple interactions is a promising route to explore novel spin-dictated multiferroicity in classic multiferroics.…”

“…111,112 In particular, large spontaneous polarization was reported in GdMnO 3 thin films, which is probably due to a self-assembled nano-twinned domain structure. 112 This result indicates that finely tuning the competing balance of multiple interactions is a promising route to explore novel spin-dictated multiferroicity in classic multiferroics. In addition, while the ground state of bulk orthorhombic YMO is E-type antiferromagnetic, a strain induced spiral spin ordering phase accompanied by spontaneous polarization was recently reported in thin films, and an intriguing memory effect was evidenced.…”

Abnormal magnetic ordering and ferromagnetism in perovskite ScMnO3 film

“…These domains are perpendicular to each other, which is very similar to twin-like domain structure in orthorhombic GdMnO 3 and TbMnO 3 films. 22,23 However, due to small grain size, it is very difficult to obtain a high quality electron diffraction pattern in our case. Domain boundary can be clearly observed in the high resolution TEM image in Figure 6(b).…”

“…Moreover, it was reported recently that nano-scale crystallographic multi-domain structure can induce ferromagnetism in other multiferroic RMnO 3 thin films such as orthorhombic TbMnO 3 and GdMnO 3 films. [22][23][24] In this letter, we fabricated orthorhombic ScMnO 3 thin film grown on LaAlO 3 (001) substrate using a hexagonal target. The crystal structure and magnetic properties are investigated and compared with other orthorhombic RMnO 3 systems.…”

“…As introduced above, self-assembly nano-scale crystallographic domain structure can induce ferromagnetism in multiferroic RMnO 3 films. [22][23][24] The plane-view TEM measurement of 60 nm film was conducted, and two typical bright field TEM images are shown in Figures 6(a) and 6(b). Self-assembly nano-scale domains are naturally formed in FIG.…”