Resistive and capacitive switching in capacitor metal/nanocomposite/metal ($\mathrm{M}/\mathrm{NC}/\mathrm{M}$) structures based on $(\mathrm{Co}\text{−}\mathrm{Fe}\text{−}\mathrm{B}{)}_x({\mathrm{Li}\mathrm{Nb}\mathrm{O}}_3{)}_{100-x}$ NC fabricated by ion-beam sputtering with metal content x ≈ 8–20 at. % is studied. The peculiarity of the structure synthesis was the use of increased oxygen content (approximately equal to 2 × ${10}^{-5}$ Torr) at the initial stage of the NC growth. The NC films, along with metal nanogranules of 3–6 nm in size, contained a large number of dispersed Co (Fe) atoms (up to approximately ${10}^{22}$ ${\mathrm{cm}}^{-3}$). Measurements are performed both in dc and ac (frequency range 5–13 MHz) regimes. When switching structures from high-resistance $(R_{\mathrm{off}})$ to low-resistance $(R_{\mathrm{on}})$ state, the effect of a strong increase in their capacity is found, which reaches 8 times at x ≈ 15 at. % and the resistance ratio $R_{\mathrm{off}}$:$R_{\mathrm{on}}$ ≈ 40. The effect is explained by the synergetic combination of the multifilamentary character of resistive switching (RS) and structural features of the samples associated, in particular, with the formation of a high-resistance and strongly polarizable ${\mathrm{Li}\mathrm{Nb}\mathrm{O}}_3$ layer near the bottom electrode of the structures. The proposed model is confirmed by investigations of RS of two-layer nanoscale $\mathrm{M}/\mathrm{NC}/{\mathrm{Li}\mathrm{Nb}\mathrm{O}}_3/\mathrm{M}$ structures as well as by studies of the magnetization of $\mathrm{M}/\mathrm{NC}/\mathrm{M}$ structures in the pristine state and after RS.

The impact of B substitution in Ni₅₀Mn₃₅In_15−xB_x Heusler alloys on the structural, magnetic, transport, and parameters of the magnetocaloric effect (MCE) has been studied by means of room-temperature X-ray diffraction and thermomagnetic measurements (in magnetic fields (H) up to 5 T, and in the temperature interval 5–400 K). Direct adiabatic temperature change (ΔT_AD) measurements have been carried out for an applied magnetic field change of 1.8 T. The transition temperatures (T-x) phase diagram has been constructed for H = 0.005 T. The MCE parameters were found to be comparable to those observed in other MCE materials such as Ni₅₀Mn_34.8In_14.2B and Ni₅₀Mn₃₅In₁₄X (X=In, Al, and Ge) Heusler alloys. The maximum absolute value of ΔT_AD = 2.5 K was observed at the magnetostructural transition for Ni₅₀Mn₃₅In_14.5B_0.5.

Magnetization, electrical resistivity, magnetoresistance, and Hall resistivity of $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.25}{\mathrm{B}}_{0.75}$ and $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.5}{\mathrm{B}}_{0.5}$ Heusler alloys were studied in a temperature range $T=80–400\mathrm{K}$ in magnetic fields up to 20 kOe. Both alloys exhibit a martensitic transformation from a high-temperature ferromagnetic austenite phase to a low-temperature, low-magnetization martensitic phase. The electrical resistivity nearly doubles as a result of the martensitic transformation, reaching 180 and 100 µΩ cm in the martensitic states of $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.25}{\mathrm{B}}_{0.75}$ and $\mathrm{N}{\mathrm{i}}_{50}\mathrm{M}{\mathrm{n}}_{35}\mathrm{I}{\mathrm{n}}_{14.5}{\mathrm{B}}_{0.5}$, respectively. The temperature dependence of the electrical resistivity does not corresponded with the Mooij correlation. The magnetoresistance is negative with a narrow negative peak at the martensitic transition. Normal and anomalous Hall effect coefficients were determined by fitting the field dependences of the Hall resistivity using magnetization data. The coefficients of the normal Hall effect for both compositions were found to decrease with temperature from positive values in the austenite to negative values in the martensite phase. None of the known correlations between the anomalous Hall effect coefficient and resistivity were satisfied. Significant changes in the values of the anomalous Hall coefficients during the martensitic transformation are explained by the difference in spin-up and spin-down state occupations in the martensite and austenite phases. First-principles calculations of the electronic structures confirm this explanation.

The magneto-optical response of the ferromagnetic semiconductor HgCdCr₂Se₄ at terahertz (THz) frequencies is studied using polarization sensitive THz time-domain spectroscopy. It is shown that the polarization state of broadband terahertz pulses, with a spectrum spanning from 0.2 THz to 2.2 THz, changes as an even function of the magnetization of the medium. Analysing the ellipticity and the rotation of the polarization of the THz radiation, we show that these effects originate from linear birefringence and dichroism, respectively, induced by the magnetic ordering. These effects are rather strong and reach 10²rad/m at an applied field of 1 kG which saturates the magnetization of the sample. Our observation serves as a proof-of-principle showing strong effects of the magnetic order on the response of a medium to electric fields at THz frequencies. These experiments also suggest the feasibility of spin-dependent transport measurements on a sub-picosecond timescale.

The Borrmann effect, which is related to the microscopic distribution of the electromagnetic field inside the primitive cell, is studied in photonic and magnetophotonic crystals. This effect, well known in x-ray spectroscopy, is responsible for the enhancement or suppression of various linear and nonlinear optical effects when the incidence angle and/or the frequency change. It is shown that by design of the primitive cell this effect can be suppressed and even inverted.