Titanium sesquioxide (Ti2O3) is drawing broad attention due to its fascinating physical properties and promising applications in the fields of energy, biomedicine, and electronics, among others. Its richness is due mainly to the strongly correlated 3d1 electrons on the Ti3+ sites. In stark contrast to titanium dioxide (TiO2), Ti2O3 has an ultra‐narrow bandgap (≈0.1 eV) at room temperature, resulting from strong correlation among the 3d1 electrons. Distinct electrical and optical properties are introduced in Ti2O3, accompanied with varied intriguing applications. Remarkable photothermal conversion, infrared photodetection, and electrocatalytic properties have been reported and explored in the past few years. Based on its unique and excellent properties, Ti2O3 has been utilized in seawater desalination, electrocatalytic water splitting, cancer therapy, hydrogen production, mid‐infrared photodetection, nitrogen fixation, Li‐ion batteries, etc. Herein, the fabrication, structural and electronic properties of Ti2O3 are comprehensively introduced, with a focused summary of recent research progress on its applications. Finally, current challenges, opportunities, and future perspectives of Ti2O3 are discussed.

Plasmons in strongly correlated systems are attracting considerable attention due to their unconventional behavior caused by electronic correlation effects. Recently, flat plasmons with nearly dispersionless frequency-wave vector relations have drawn significant interest because of their intriguing physical origin and promising applications. However, these flat plasmons exist primarily in low-dimensional materials with limited wave vector magnitudes (q < ~0.7 Å−1). Here, we show that long-lived flat plasmons can propagate up to ~1.2 Å−1 in α-Ti2O3, a strongly correlated three-dimensional Mott-insulator, with an ultra-small energy fluctuation (<40 meV). The strong correlation effect renormalizes the electronic bands near Fermi level with a small bandwidth, which is responsible for the flat plasmons in α-Ti2O3. Moreover, these flat plasmons are not affected by Landau damping over a wide range of wave vectors (q < ~1.2 Å−1) due to symmetry constrains on the electron wavefunctions. Our work provides a strategy for exploring flat plasmons in strongly correlated systems, which in turn may give rise to novel plasmonic devices in which flat and long-lived plasmons are desirable.

<abstract><p>This paper studies a two-layer control strategy for optimal operational control which is prevalent in industrial production. The upper layer determines and adjusts the target set values, while the lower layer makes the loop output track the target value. In the two-layer structure optimal setting control system, the widely used PID controller is used in the bottom layer. Firstly, the parameters of the PID controller are obtained by solving linear matrix inequalities (LMI). Secondly, for industrial processes with nonlinear harmonic disturbances, a disturbance observer is designed to estimate these disturbances. Thirdly, the effects of disturbances or noises are minimized by dynamically adjusting the setting points. This method does not change the structure or parameters of the bottom controller, and thus meets the actual industrial requirements to a certain extent. Finally, in the numerical simulation section, the value of the performance index before set-points adjustment is compared with that after set-points adjustment.</p></abstract>

Antiferromagnetic (AFM) materials are attracting tremendous attention due to their spintronic applications and associated novel topological phenomena. However, detecting and identifying the spin configurations in AFM materials are quite challenging due to the absence of net magnetization. Herein, we report the practicality of utilizing the planar Hall effect (PHE) to detect and distinguish “cluster magnetic multipoles” in AFM Nd2Ir2O7 (NIO-227) fully strained films. By imposing compressive strain on the spin structure of NIO-227, we artificially induced cluster magnetic multipoles, namely dipoles and A2- and T1-octupoles. Importantly, under magnetic field rotation, each magnetic multipole exhibits distinctive harmonics of the PHE oscillation. Moreover, the planar Hall conductivity has a nonlinear magnetic field dependence, which can be attributed to the magnetic response of the cluster magnetic octupoles. Our work provides a strategy for identifying cluster magnetic multipoles in AFM systems and would promote octupole-based AFM spintronics.