Doped‐HfO2 thin films with ferroelectricity have attracted great attention due to their potential application in semiconductor industry as negative capacitance and resistance switching memory. Despite Hf0.5Zr0.5O2 (HZO) thin films having the most robust ferroelectric properties among all doped‐HfO2 thin films, the realization of single orthorhombic phase HZO thin films is not achieved, while the direct evidence between the structural–properties relationship of orthorhombic phase HZO and ferroelectricity is not confirmed. In this work, the growth of single orthorhombic phase HZO thin films with decent ferroelectricity and resistive switching behavior is reported. With the aid of advanced structural characterization techniques, the HZO thin film is confirmed to be in the single orthorhombic phase. Next, using scanning probe microscopy techniques and macroscopic ferroelectric measurements, the single phase HZO thin films exhibit ferroelectric properties with a remanent polarization of about 20 µC cm−2. Interestingly, the HZO thin film shows ferroelectric resistive switching with an ROFF/RON ratio of about 16 100% with excellent device performance. Furthermore, brain‐like learning behavior is also observed in the HZO thin film. These results may serve to stimulate the study of ferroelectric properties of HZO thin films and their application in the electronic industry.

Room-temperature ferromagnetism has been observed in undoped SnO2 nanostructures with various morphologies synthesized by a chemical vapor deposition (CVD) method. The magnetization depends on the oxygen flow rate during the CVD synthesis and decreases monotonically with the increase of the oxygen flow rate. X-ray diffraction and X-ray photoelectron spectroscopy measurements show that all the samples possess a typical rutile structure, and no other impurity phases are observed. Photoluminescence and X-ray photoelectron spectroscopies were employed to evidence the presence of oxygen vacancies in these samples and reveal that the oxygen vacancies contribute to the ferromagnetism. To further test the oxygen-vacancy-related ferromagnetism, post-thermal annealing in different ambiances was performed. The results confirm that the oxygen vacancies, not Sn interstitials, play a crucial role in inducing the ferromagnetism in undoped SnO2 nanostructures.

The Rashba effect plays important roles in emerging quantum materials physics and potential spintronic applications, entailing both the spin orbit interaction (SOI) and broken inversion symmetry. In this work, we devise asymmetric oxide heterostructures of LaAlO 3 //SrTiO 3 /LaAlO 3 (LAO//STO/LAO) to study the Rashba effect in STO with an initial centrosymmetric structure, and broken inversion symmetry is created by the inequivalent bottom and top interfaces due to their opposite polar discontinuities. Furthermore, we report the observation of a transition from the cubic Rashba effect to the coexistence of linear and cubic Rashba effects in the oxide heterostructures, which is controlled by the filling of Ti orbitals. Such asymmetric oxide heterostructures with initially centrosymmetric materials provide a general strategy for tuning the Rashba SOI in artificial quantum materials.

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Multifunctional films can have important applications. Transparent and flexible films with high conductivity and magnetic properties can be used in many areas, such as electromagnetic interference (EMI) shielding, magnetic switching, microwave absorption, and also biotechnology. Herein, novel highly conductive and superparamagnetic thin films with excellent transparency and flexibility have been demonstrated. The films were formed from a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS; Clevios PH1000) aqueous solution added with iron oxide (FeO) nanoparticles that have a size of ∼20 nm by spin-coating. The PEDOT:PSS/FeO films have a high conductivity of 1080 S/cm through treatment with methylammonium iodide in an organic solvent. The high-conductivity PEDOT:PSS/FeO films can also have a saturation magnetization of 25.5 emu/g and an EMI shielding effectiveness of more than 40 dB in the 8-12.5 GHz (X band) frequency range. The PEDOT:PSS/FeO films have additional advantages, like excellent transparency, good mechanical flexibility, low cost, and light weight. In addition, we fabricate flexible PEDOT:PSS/FeO silk threads with a high magnetism and conductivity.