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Electric manipulation of magnetization is essential for the integration of magnetic functionalities in integrated circuits. Spin-orbit torque (SOT), originating from the coupling of electron spin and orbital motion through spin-orbital interaction, can effectively manipulate magnetization. Symmetry breaking plays an important role in spintronics based on SOT. SOT requires inversion asymmetry in order to have a net effect on magnetic materials, which is commonly realized by spatial asymmetry: a thin magnetic layer sandwiched between two dissimilar layers. This kind of structure restricts the SOT by mirror and rotational symmetries to have a particular form: an “antidamping-like” component oriented in the film plane even upon reversal of the magnetization direction. Consequently, magnetization perpendicular to the film plane cannot be deterministically switched with pure electric current. To achieve all-electric switching of perpendicular magnetization, it is necessary to break the mirror and rotational symmetries of the sandwiched structure.

The ultrafast dynamics of photoexcited carriers and coherent phonons in ultrathin Bi2Te3 thermoelectric films are studied through transient differential transmission spectroscopy. An ultralow frequency coherent optical phonon at 0.16 THz emerges, especially in ultrathin films, and it is ascribed to interlayer breathing modes. It can divide the ultrathin films into two groups which have out-of-phase vibration along the normal of a film plane, causing a destructive interference between in-plane propagating thermal waves in the two groups of quintuple layers, and thus possibly reducing the thermal conductivity of the ultrathin films. The excitation power dependence of ultrafast dynamics reveals carrier-carrier scattering dominating thermalization, which provides a microscopic understanding of the reported high electrical conductivity and anomalously high power factor of ultrathin Bi2Te3 films at room temperature.

We demonstrated atomic diffusion bonding (ADB) of wafers using AlN films at room temperature. Results showed that crystal lattice rearrangement occurred at the bonded interface and integrated AlN film with c-axis perpendicular to the film plane formed.

We demonstrate a new structural optimization of cobalt–(barium fluoride) lateral nanogranular films, achieving independently variable direct current (DC) and alternating current (AC) tunneling effects, in the film plane and out of the plane, respectively. Lateral nanogranular films were successfully fabricated via programmable tandem sputtering. Flat-shaped magnetic Co nanogranules were periodically inserted between dielectric barium fluoride layers of different thicknesses. All the lateral nanogranular films were insulating, with electrical resistivities ρ exceeding 1013 μΩ·cm, even with a Co content as high as 30 at.%. A lateral tunneling magnetoresistance (TMR) effect and vertical tunneling magnetodielectric (TMD) effect were found in the same lateral nanogranular film with 30 at.% Co. For a nanogranular film with lateral Co nanoparticles, the sensitivity of both the TMR and TMD ratio were improved at small magnetic fields compared with conventional films with spherical Co nanoparticles, reflecting its small saturation magnetic field. This layer-ordered metal–insulator nanogranular structure has potential applications in AC/DC hybrid elements as a high-sensitivity magnetic sensor.

Laminar heterostructures composed by materials with different ferroic properties have been proposed for the control of magnetism with an applied voltage. We present here a study of the structural and magnetic properties of chemically disordered FePt ferromagnetic films of different thicknesses that have been sputter-deposited on ferroelectric PMN-PT (011) single crystals. By means of static and dynamic magnetic measurements we have found that it is possible to switch the magnetization easy axis by 90° if an electric field is applied in a direction perpendicular to the film plane. Using ferromagnetic resonance techniques we have estimated the strain induced magnetoelectric coupling of the FePt/PMN-PT heterostructure, obtaining ME = 477 ( 15 ) Oe m/MV for FePt thicknesses greater than 26 nm, which corresponds to an average magnetoelastic constant B = − 13 . 2 ( 1 . 1 ) MJ/m 3 . The associated saturation magnetostriction was estimated in λ s ∼ 90 ppm. Films thinner than 26 nm present corresponding values that are smaller by approximately 20%. A possible explanation for this difference is the well known transition from planar to stripe-like magnetic domains that occurs in FePt around this film thickness. However, this thickness dependence of ME is relatively smaller than that found in other ferromagnets such as Fe or FeGa, which makes FePt a potential candidate for thin film applications in magnetoelectronic devices.

The extraordinary ability of poly(2,6-dimethyl-1,4-phenylene)oxide (PPO) dense films, exhibiting a nanoporous-crystalline (NC) phase, to absorb traces of organic pollutants dissolved in water is shown. Equilibrium uptakes and sorption kinetics of perchloroethylene (PCE) are much higher and faster than for the corresponding amorphous films. For sorption kinetics, particularly relevant is a control of the planar orientation of the NC phase. For instance, for PCE sorption from 50 ppm aqueous solutions, a NC α form film with orientation of the crystalline polymer chains being preferentially perpendicular to the film plane (c⊥ orientation) exhibit a diffusivity nearly 14 times higher than for a NC film with crystalline polymer chains being preferentially parallel to the film plane (c// orientation) and nearly 88 times higher than for the starting amorphous PPO film. This phenomenon is rationalized in terms of crystalline channels being preferentially perpendicular to the film plane. Moreover, equilibrium uptakes for NC PPO films are much higher than for NC sPS films. For instance, for sorption experiments from PCE 50 ppm aqueous solutions, equilibrium uptakes for NC PPO and sPS films are nearly 15 wt% and 2 wt%, respectively. This phenomenon is rationalized by the high-free volume of both NC and amorphous phases of PPO.

Co-crystallization of amorphous poly(2,6-dimethyl-1,4-phenylene) oxide (PPO) films, as induced by sorption at different temperatures of many liquid guest molecules, is explored. Both for co-crystalline (CC) and corresponding nanoporous-crystalline (NC) films, kinds of and degree of planar orientation, which are relevant for their properties and applications, can be controlled by the guest sorption procedure. In particular, crystalline polymer chain orientation preferentially perpendicular to the film plane is favored by bulky guest molecules and by low guest sorption temperatures, i.e. by slow guest uptakes. Guest sorption kinetics and Scanning Electron Microscopy ( SEM ) support a simple mechanism that rationalizes the kinds of planar orientation of crystalline PPO chains. Slow guest uptakes imply polymer co-crystallization in spatial confinement, producing lamellae that are oriented flat-on to the film surface and hence polymer chain axes preferentially perpendicular to the film plane (c⊥ orientation). Fast guest uptakes imply polymer co-crystallization leading to fibrils that are parallel to the film surface and hence to polymer chain axes being preferentially parallel to the film plane (c// orientation).