Magnetoelastic constant of thin films determined by a four-point bending apparatus

We have developed a method to variably induce lattice strains and to quantitatively evaluate the induced magnetic anisotropy. Both tensile and compressive strains were introduced into epitaxial films of cobalt ferrite (CFO) grown on a single crystal MgO(001) substrate using a four-point bending apparatus made of a plastic material fabricated by a 3D printer. The change in magnetic anisotropy due to bending strain can be measured quantitatively by using the conventional magneto-torque meter. The strain-induced magnetic anisotropy increased with the tensile strain and decreased with the compressive strain as expected from a phenomenological magnetoelastic theory. The magnetoelastic constant obtained from the changes in bending strains shows quantitatively good agreement with that of the CFO films with a uniaxial epitaxial strain. This signifies that the magnetoelastic constant can be evaluated by measuring only one film sample with strains applied by using the bending apparatus.

Терагерцевая генерация в эпитаксиальных пленках InAs

We present the results of terahertz generation studies under excitation via femtosecond lasers pulses epitaxial films of InAs, which were synthesized on semi-insulating and highly doped GaAs substrates. It is shown that a terahertz emitter based on epitaxial InAs film grown on a heavily doped GaAs n-type substrate, has the same terahertz generation efficiency as the InAs-film emitter grown on a semi-isolating GaAs substrate, but it has a significantly better spectral resolution, which is mainly determined by the parameters of the optical delay line and the femtosecond laser’s stability.

Analysis of the possibility of creating an acoustic velocity sensor using GaN epitaxial films

This paper results in results of analyzing the possibility of creating an acoustic velocity sensor using epitaxial GaN films. Technology for the fabrication of a microelectromechanical acoustic velocity sensor was developed and a prototype of the sensor was produced. The simulation of the characteristics of the obtained acoustic velocity sensors was carried out on the basis of the measured electrical characteristics, where the sensitivity and the directional pattern were determined.

Tin monosulfide (SnS) epitaxial films grown by RF magnetron sputtering and sulfurization on MgO(100) substrates

The crystallographic and electrical properties of tin monosulfide (SnS) epitaxial thin films grown by RF magnetron sputtering and sulfurization were investigated. The SnS(040)-oriented films were grown on an MgO(100) substrate. Two types of four-fold rotational symmetrical in-plane orientations, offset by 45° from each other, were observed using X-ray diffraction. The rotational symmetry was also observed using cross-sectional transmission electron microscopy. The electrical properties of the SnS films were controlled by varying the sulfurization temperature, and the carrier transport of all the SnS epitaxial films was mainly limited by grain boundary scattering. The activation energies of the carrier concentration before and after sulfurization of the films were estimated to be approximately 0.26 ± 0.02 eV and 0.20 ± 0.01 eV, respectively, based on temperature-dependent Hall measurements. These values mainly correspond to the acceptor level energy of Sn vacancy with a high/low potential barrier height around the grain boundary.