Epitaxial Strain Enhanced Ferroelectric Polarization toward a Giant Tunneling Electroresistance.

A substantial ferroelectric polarization is the key for designing high-performance ferroelectric nonvolatile memories. As a promising candidate system, the BaTiO/LaSrMnO (BTO/LSMO) ferroelectric/ferromagnetic heterostructure has attracted a lot of attention thanks to the merits of high Curie temperature, large spin polarization, and low ferroelectric coercivity. Nevertheless, the BTO/LSMO heterostructure suffers from a moderate FE polarization, primarily due to the quick film-thickness-driven strain relaxation.

Taming heat with tiny pressure.

Heat is almost everywhere. Unlike electricity, which can be easily manipulated, the current ability to control heat is still highly limited owing to spontaneous thermal dissipation imposed by the second law of thermodynamics. Optical illumination and pressure have been used to switch endothermic/exothermic responses of materials via phase transitions; however, these strategies are less cost-effective and unscalable.

Gradient tungsten-doped BiTiNbO ferroelectric photocatalysts with additional built-in electric field for efficient overall water splitting.

BiTiNbO, a layered ferroelectric photocatalyst, exhibits great potential for overall water splitting through efficient intralayer separation of photogenerated carriers motivated by a depolarization field along the in-plane a-axis. However, the poor interlayer transport of carriers along the out-of-plane c-axis, caused by the significant potential barrier between layers, leads to a high probability of carrier recombination and consequently results in low photocatalytic activity. Here, we have developed an efficient photocatalyst consisting of BiTiNbO nanosheets with a gradient tungsten (W) doping along the c-axis.

Schottky Barrier Control of Self-Polarization for a Colossal Ferroelectric Resistive Switching.

Controlling the domain evolution is critical both for optimizing ferroelectric properties and for designing functional electronic devices. Here we report an approach of using the Schottky barrier formed at the metal/ferroelectric interface to tailor the self-polarization states of a model ferroelectric thin film heterostructure system SrRuO/(Bi,Sm)FeO. Upon complementary investigations of the piezoresponse force microscopy, electric transport measurements, X-ray photoelectron/absorption spectra, and theoretical studies, we demonstrate that Sm doping changes the concentration and spatial distribution of oxygen vacancies with the tunable host Fermi level which modulates the SrRuO/(Bi,Sm)FeO Schottky barrier and the depolarization field, leading to the evolution of the system from a single domain of downward polarization to polydomain states.

Photocatalytic Overall Water Splitting over PbTiO Modulated by Oxygen Vacancy and Ferroelectric Polarization.

Ferroelectric materials hold great promise in the field of photocatalytic water splitting due to their spontaneous polarization that sets up an inherent internal field for the spatial separation of photogenerated charges. The ferroelectric polarization, however, is generally accompanied by some intrinsic defects, particularly oxygen vacancies, whose impact upon photocatalysis is far from being fully understood and modulated. Here, we have studied the role of oxygen vacancies over the photocatalytic behavior of single-domain PbTiO through a combination of theoretical and experimental viewpoints.

Regulation of Ferroelectric Polarization to Achieve Efficient Charge Separation and Transfer in Particulate RuO /BiFeO for High Photocatalytic Water Oxidation Activity.

Exploiting spontaneous polarization of ferroelectric materials to achieve high charge separation efficiency is an intriguing but challenging research topic in solar energy conversion. This work shows that loading high work function RuO cocatalyst on BiFeO (BFO) nanoparticles enhances the intrinsic ferroelectric polarization by efficient screening of charges to RuO via RuO /BFO heterojunction. This leads to enhancement of the surface photovoltage of RuO /BFO single nanoparticles nearly 3 times, the driving force for charge separation and transfer in photocatalytic reactions.