Ti O nanoparticles with high performance of photothermal conversion are demonstrated for the first time. Benefiting from the nanosize and narrow-bandgap features, the Ti O nanoparticles possess strong light absorption and nearly 100% internal solar-thermal conversion efficiency. Furthermore, Ti O -nanoparticle-based thin film shows potential use in seawater desalination and purification.

Magnetic semiconductors are highly sought in spintronics, which allow not only the control of charge carriers like in traditional electronics, but also the control of spin states. However, almost all known magnetic semiconductors are featured with bandgaps larger than 1 eV, which limits their applications in long‐wavelength regimes. In this work, the discovery of orthorhombic‐structured Ti2O3 films is reported as a unique narrow‐bandgap (≈0.1 eV) ferromagnetic oxide semiconductor. In contrast, the well‐known corundum‐structured Ti2O3 polymorph has an antiferromagnetic ground state. This comprehensive study on epitaxial Ti2O3 thin films reveals strong correlations between structure, electrical, and magnetic properties. The new orthorhombic Ti2O3 polymorph is found to be n‐type with a very high electron concentration, while the bulk‐type trigonal‐structured Ti2O3 is p‐type. More interestingly, in contrast to the antiferromagnetic ground state of trigonal bulk Ti2O3, unexpected ferromagnetism with a transition temperature well above room temperature is observed in the orthorhombic Ti2O3, which is confirmed by X‐ray magnetic circular dichroism measurements. Using first‐principles calculations, the ferromagnetism is attributed to a particular type of oxygen vacancies in the orthorhombic Ti2O3. The room‐temperature ferromagnetism observed in orthorhombic‐structured Ti2O3, demonstrates a new route toward controlling magnetism in epitaxial oxide films through selective stabilization of polymorph phases.

The search for new superconductors capable of carrying loss-free current has been a research theme in condensed matter physics for the past decade. Among superconducting compounds, titanates have not been pursued as much as Cu 2+ (3d 9 ) (cuprate) and Fe 2+ (3d 6 ) (pnictide) compounds. Particularly, Ti 3+ -based compounds or electron systems with a special 3d 1 filling are thought to be promising candidates as high-T C superconductors, but there has been no report on such pure Ti 3+ -based superconducting titanates. With the advent of thin-film growth technology, stabilizing new structural phases in single-crystalline thin films is a promising strategy to realize physical properties that are absent in the bulk counterparts. Herein, we report the discovery of unexpected superconductivity in orthorhombicstructured thin films of Ti 2 O 3 , a 3d 1 electron system, which is in strong contrast to the conventional semiconducting corundum-structured Ti 2 O 3 . This is the first report of superconductivity in a titanate with a pure 3d 1 electron configuration. Superconductivity at 8 K was observed in the orthorhombic Ti 2 O 3 films. Leveraging the strong structureproperty correlation in transition-metal oxides, our discovery introduces a previously unrecognized route for inducing emergent superconductivity in a newly stabilized polymorph phase in epitaxial thin films.

Interfaces between materials present unique opportunities for the discovery of intriguing quantum phenomena. Here, we explore the possibility that, in the case of superlattices, if one of the layers is made ultrathin, unexpected properties can be induced between the two bracketing interfaces. We pursue this objective by combining advanced growth and characterization techniques with theoretical calculations. Using prototype La 2/3 Sr 1/3 MnO 3 (LSMO)/ BaTiO 3 (BTO) superlattices, we observe a structural evolution in the LSMO layers as a function of thickness. Atomic-resolution EM and spectroscopy reveal an unusual polar structure phase in ultrathin LSMO at a critical thickness caused by interfacing with the adjacent BTO layers, which is confirmed by first principles calculations. Most important is the fact that this polar phase is accompanied by reemergent ferromagnetism, making this system a potential candidate for ultrathin ferroelectrics with ferromagnetic ordering. Monte Carlo simulations illustrate the important role of spin-lattice coupling in LSMO. These results open up a conceptually intriguing recipe for developing functional ultrathin materials via interface-induced spin-lattice coupling.spin-lattice coupling | interfaces | magnetic/electric | structural transition | ultrathin films I nterface physics has emerged as one of the most popular methods to discover unique phenomena caused by broken symmetry (1-6). In transition metal oxide (TMO) interfaces, the different electronic, magnetic, lattice, and orbital properties of two adjoined materials lead to fascinating properties that are often radically different from those of the two component bulk materials (7-10). It would seem that we are on the verge of being able to design (11) or engineer (12) the properties of interfaces.Although the behavior of individual interfaces has been widely investigated, how two or more interfaces behave within superlattices (SLs) remains an interesting and open topic (13,14). As shown in Fig. 1A, when two interfaces are geometrically close enough, they can drastically alter the properties of the material in between because of proximity effects. Unlike layered compounds, such as Fe-based superconductors and cuprates, which have pronounced 2D properties, most perovskites with the chemical formula ABO 3 exhibit drastic decreases in their functionalities under reduced dimensionality (i.e., ultrathin materials). This property has hindered the exploration and development of active low-dimensional materials (15, 16). Therefore, exploring ultrathin materials confined by two interfaces is a rational approach to see whether interfacial effects can be exploited to achieve desired functionalities.In this work, we present an example of using the structural phase change induced by two adjacent interfaces as a route to design ultrathin TMOs. We choose two materials with distinct properties: BaTiO 3 (BTO), which in its bulk form, is polar ferroelectric, and La 2/3 Sr 1/3 MnO 3 (LSMO), which in its bulk form, is nonpolar/tilt ferromagnetic....

Efficient perovskite solar cells fabricated by manganese cations incorporated in hybrid perovskites.