Flexible ε-Fe₂O₃-Terephthalate Thin-Film Magnets through ALD/MLD

Abstract

Pliable and lightweight thin-film magnets performing at room temperature are indispensable ingredients of the next-generation flexible electronics. However, conventional inorganic magnets based on f-block metals are rigid and heavy, whereas the emerging organic/molecular magnets are inferior regarding their magnetic characteristics. Here we fuse the best features of the two worlds, by tailoring ε-Fe 2 O 3 -terephthalate superlattice thin films with inbuilt flexibility due to the thin organic layers intimately embedded within the ferrimagnetic ε-Fe 2 O 3 matrix; these films are also sustainable as they do not contain rare heavy metals. The films are grown with sub-nanometer-scale accuracy from gaseous precursors using the atomic/molecular layer deposition (ALD/MLD) technique. Tensile tests confirm the expected increased flexibility with increasing organic content reaching a 3-fold decrease in critical bending radius (2.4 ± 0.3 mm) as compared to ε-Fe 2 O 3 thin film (7.7 ± 0.3 mm). Most remarkably, these hybrid ε-Fe 2 O 3 -terephthalate films do not compromise the exceptional intrinsic magnetic characteristics of the ε-Fe 2 O 3 phase, in particular the ultrahigh coercive force (∼2 kOe) even at room temperature.

Molecular layer deposited alucone thin films from long-chain organic precursors: from brittle to ductile mechanical characteristics

“…Nanoindentation studies have shown that elastic modulus and hardness of the hybrid films can be decreased in comparison to the parent oxides, 18,20 while tensile experiments have indicated that stretchability and flexibility can be increased compared to oxides, 17,19 and tailored in nanolaminate/superlattice structures. 17,22 The highest reported value for the crack onset strain (COS) for alucones is 1.8 % for (300-nm) films deposited via the trimethyl aluminum/1,2-ethanediol process, and the fracture behavior is still characteristic for brittle materials. 19 Even being relatively brittle, the short-chain alucones have been shown to improve the mechanical integrity of the Si nanoparticle electrodes and the capacity retention for Li-ion batteries.…”

Textile‐Integrated ZnO‐Based Thermoelectric Device Using Atomic Layer Deposition

“…However, we recently demonstrated for ALD/MLD‐grown magnetic metal oxide–organic thin films that in particular such SL films with additional organic layers within the inorganic matrix are appreciably flexible. [ 48 ] Also, we intentionally bent our TE textile devices while handling them, both before and in between the measurements, and found them durable enough. They were also found highly stable in open air, showing no changes in their TE performance even after extended storage in air.…”

Photoactive Thin-Film Structures of Curcumin, TiO2 and ZnO

“…It was shown that the Cur moieties are bonded to the Ti atoms via curcumin’s hydroxyl groups, but the β-diketone and methoxy groups were left intact. An attractive aspect in this ALD/MLD approach is that it is possible to further combine the ALD/MLD-grown metal-Cur layers with additional ALD-grown inorganic layers into different nanoscale multilayer structures [ 30 , 33 , 34 ]. In the present study, we will push this option forward, and also investigate the possibility to combine the ALD, MLD and S-C techniques to take a full advantage of their complementary benefits.…”