Mingfeng Chen

Sodium-hydrogen exchanger NHA1 and NHA2 control sperm motility and male fertility.

Our previous work identified NHA1, a testis-specific sodium–hydrogen exchanger, is specifically localized on the principal piece of mouse sperm flagellum. Our subsequent study suggested that the number of newborns and fertility rate of NHA1-vaccinated female mice are significantly stepped down. In order to define the physiological function of NHA1 in spermatozoa, we generated Nha1Fx/Fx, Zp3-Cre (hereafter called Nha1 cKO) mice and found that Nha1 cKO males were viable and subfertile with reduced sperm motility. Notably, cyclic AMP (cAMP) synthesis by soluble adenylyl cyclase (sAC) was attenuated in Nha1 cKO spermatozoa and cAMP analogs restored sperm motility. Similar to Nha1 cKO males, Nha2Fx/Fx, Zp3-Cre (hereafter called Nha2 cKO) male mice were subfertile, indicating these two Nha genes may be functionally redundant. Furthermore, we demonstrated that male mice lacking Nha1 and Nha2 genes (hereafter called Nha1/2 dKO mice) were completely infertile, with severely diminished sperm motility owing to attenuated sAC-cAMP signaling. Importantly, principal piece distribution of NHA1 in spermatozoa are phylogenetically conserved in spermatogenesis. Collectively, our data revealed that NHA1 and NHA2 function as a key sodium–hydrogen exchanger responsible for sperm motility after leaving the cauda epididymidis.

Controllable conductive readout in self-assembled, topologically confined ferroelectric domain walls

Charged domain walls in ferroelectrics exhibit a quasi-two-dimensional conduction path coupled to the surrounding polarization. They have been proposed for use as non-volatile memory with non-destructive operation and ultralow energy consumption. Yet the evolution of domain walls during polarization switching makes it challenging to control their location and conductance precisely, a prerequisite for controlled read–write schemes and for integration in scalable memory devices. Here, we explore and reversibly switch the polarization of square BiFeO3 nanoislands in a self-assembled array. Each island confines cross-shaped, charged domain walls in a centre-type domain. Electrostatic and geometric boundary conditions induce two stable domain configurations: centre-convergent and centre-divergent. We switch the polarization deterministically back and forth between these two states, which alters the domain wall conductance by three orders of magnitude, while the position of the domain wall remains static because of its confinement within the BiFeO3 islands.Self-assembled, ferroelectric BiFeO3 nanoislands confine centre-type quad-domains that can be switched reliably by means of an electric field, changing the domain-wall conductance by three orders of magnitude.

Publisher Correction: Controllable conductive readout in self-assembled, topologically confined ferroelectric domain walls

In the version of this Article originally published, the corresponding author names in the author list appeared in the reverse order; they should have read ‘Jinxing Zhang and Ce-Wan Nan’. The order of these authors’ initials in the ‘Correspondence and requests for materials’ statement were similarly affected. These errors have now been corrected in all versions of the Article.

Ferromagnetism and matrix-dependent charge transfer in strained LaMnO3–LaCoO3 superlattices

ABSTRACT Interfacial magnetism at transition-metal oxide interfaces is of tremendous interest. The emergence of ferromagnetism and a matrix-dependent charge transfer between Co and Mn ions in the interdiffusion region of compressively strained LaMnO3–LaCoO3 superlattices (SLs) were studied. The SLs exhibit considerable ferromagnetism, which is negligible in both constituents. This is explained by the matrix-dependent charge transfer between Co and Mn ions. That is, the valence state of diffused Co ions into LaMnO3 shifts from 3+ to 2+ by adopting one electron from Mn3+, inducing the same amount of Mn4+, while the Mn ions that diffuses into LaCoO3 remains Mn3+. GRAPHICAL ABSTRACT IMPACT STATEMENT Matrix-dependent charge transfer effect was induced by the interplay between intrinsic and extrinsic effect in transition-metal oxides superlattices, which could be used to site-selectively modulate the electronic and magnetic states.

Low voltage induced reversible magnetoelectric coupling in Fe3O4 thin films for voltage tunable spintronic devices

The ongoing demand for efficient and low-energy consumption spintronic devices has motivated the idea of manipulating magnetism by ionic liquid (IL) electrolyte gating at low voltages. Although magnetoelectric (ME) coupling has already been realized in some field-effect-transistor (FET) structures, some vital parameters such as giant ME coupling coefficient, excellent reversibility and low gating voltage seldom come at the same time, which greatly suppresses industrialization. Here we demonstrate a large 552 Oe spin dynamics modulation of Fe3O4 thin films induced at a gating voltage of Vg = +1.5 V in an IL-gated Au/[DEME]+[TFSI]−/Fe3O4/MgO heterostructure with good reversibility up to 80 cycles, giving rise to a high ME coefficient of 368 Oe V−1. Such a large ME tunability under low Vg could be attributed to the electric field (E-field) induced ionic transformation between Fe2+ and Fe3+ at the interface. The tiny thickness change (∼2 angstrom) and roughness change of Fe3O4 films under Vg = +1.5 V illustrated by in situ X-ray reflection (XRR) give a reasonable explanation of the outstanding reversible property. Interestingly, it is found that the Verwey transition temperature of Fe3O4 has a strong dependence on Vg, revealing the potential of IL gating control of the intrinsic spin ordering inside magnetic films. This work drives forward the low-voltage induced reversible ME coupling to high-performance spintronic devices.

Effects of annealing process and the additive on the electrical properties of chemical solution deposition derived 0.65Pb(Mg 1/3 Nb 2/3 )O 3 –0.35PbTiO 3 thin films

Abstract0.65Pb(Mg1/3Nb2/3)O3–0.35PbTiO3 (PMN–PT) thin films were deposited on (111)Pt/Ti/SiO2/Si substrates via the chemical solution deposition. Both of the annealing process and additive methanamide play an obvious part in the structure and electrical properties of PMN–PT films. The optimized high-qualitied PMN–PT thin film in present work is fabricated with the methanamide in the precursor and annealed at 650xa0°C for 20xa0min. The film exhibits pure perovskite phase and superior ferroelectricity. The saturation polarization Ps and remanent polarization Pr are 52.1xa0µC/cm2 and 18.7xa0µC/cm2 at 500xa0kV/cm with 1000xa0Hz. It also shows low leakage current density of approximately 1.0u2009×u200910−u20098xa0A/cm2 at 200xa0kV/cm.

Thermal Driven Giant Spin Dynamics at Three-Dimensional Heteroepitaxial Interface in Ni0.5Zn0.5Fe2O4/BaTiO3-Pillar Nanocomposites

Traditional magnetostrictive/piezoelectric laminated composites rely on the two-dimensional interface that transfers stress/strain to achieve the large magnetoelectric (ME) coupling, nevertheless, they suffer from the theoretical limitation of the strain effect and of the substrate clamping effect in real ME applications. In this work, 3D NZFO/BTO-pillar nanocomposite films were grown on SrTiO3 by template-assisted pulsed laser deposition, where BaTiO3 (BTO) nanopillars appeared in an array with distinct phase transitions as the cores were covered by NiZn ferrite (NZFO) layer. The perfect 3D heteroepitaxial interface between BTO and NZFO phases can be identified without any edge dislocations, which allows effective strain transfer at the 3D interface. The 3D structure nanocomposites enable the strong two magnon scattering (TMS) effect that enhances ME coupling at the interface and reduces the clamping effect by strain relaxation. Thereby, a large FMR field shift of 1866 Oe in NZFO/BTO-pillar nanocomposite was obtained at the TMS critical angle near the BTO nanopillars phase transition of 255 K.

Oxygen Vacancy Dynamics at Room Temperature in Oxide Heterostructures

Oxygen vacancy dynamic behavior at room temperature in complex oxides was carefully explored by using a combined approach of ion liquid gating technique and resistance measurements. Heterostructures of PrBaCo2O5+δ/Gd2O3-doped CeO2 epitaxial thin films were fabricated on (001) Y2O3-stabilized ZrO2 single crystal substrates for systematically investigating the oxygen redox dynamics. The oxygen dynamic changes as response to the gating voltage and duration were precisely detected by in situ resistance measurements. A reversible and nonvolatile resistive switching dynamics was detected at room temperature under the gating voltage >13.5 V with pulse duration >1 s.

Ca doping effect on the magnetic and electronic transport properties in double perovskite PrBaCo2O5+δ films

Ca doped double perovskite PrBa1-xCaxCo2O5+δ (xu2009=u20090, 0.3, and 0.5) thin films were epitaxially grown on the (001) SrTiO3 substrates to systematically investigate the A′ site doping effect on the magnetic and electronic transport properties. With the increase in the Ca content, the magnetization measurements on the films show that the magnetic moments are significantly increased and the largest magnetic moment of 88u2009emu/cm3 can be achieved in the film with xu2009=u20090.5 or about 90 times larger than that from the undoped PrBaCo2O5+δ film. The electronic transport property measurements on the films indicate that the electrical conductivity can be altered by various Ca doping contents. It is interesting to note that both undoped PrBaCo2O5+δ and PrBa0.5Ca0.5Co2O5+δ films exhibit simple activation behavior, but the PrBa0.7Ca0.3Co2O5+δ film exhibits the 3D variable-range hopping mode conduction.

Interface-Induced Enhancement of Ferromagnetism in Insulating LaMnO3 Ultrathin Films

Engineering ferromagnetism, by modulating its magnitude or anisotropy, is an important topic in the field of magnetism and spintronics. Among different types of magnetic materials, ferromagnetic insulators, in which magnetic moment unusually coexists with localized electrons, are of particular interest. Here, we report a remarkable interfacial enhancement of the ferromagnetism by adding one unit-cell LaAlO3 adjacent to an insulating LaMnO3 ultrathin film. The enhancement of ferromagnetism is explained in terms of charge transfer at the interface, as evidenced by X-ray absorption spectroscopy and ab initio calculations. This study demonstrates an effective and dramatic approach to modulate the functionality of ferromagnetic insulators, contributing to the arsenal of engineering techniques for future spintronics.