The mechanism of the peculiar transport properties around the magnetic ordering temperature of semiconducting antiferromagnetic ${\mathrm{EuCd}}_2{\mathrm{P}}_2$ is not yet understood. With a huge peak in the resistivity observed above the Néel temperature $T_{\mathrm{N}}=10.6\mathrm{K}$, it exhibits a colossal magnetoresistance effect. Recent reports on observations of ferromagnetic contributions above $T_{\mathrm{N}}$ as well as metallic behavior below this temperature have motivated us to perform a comprehensive characterization of this material, including its resistivity, heat capacity, magnetic properties, and electronic structure. Our transport measurements revealed quite different temperature dependence of resistivity with the maximum at 14 K instead of previously reported 18 K. Low-field susceptibility data support the presence of static ferromagnetism above $T_{\mathrm{N}}$ and show a complex behavior of the material at small applied magnetic fields. Namely, signatures of reorientation of magnetic domains are observed up to $T=16$ K. Our magnetization measurements indicate a magnetocrystalline anisotropy which also leads to a preferred alignment of the magnetic clusters above $T_{\mathrm{N}}$. The momentum-resolved photoemission experiments at temperatures from 24 down to 2.5 K indicate the permanent presence of a fundamental band gap without change of the electronic structure when going through $T_N$ that is in contradiction with previous results. We performed ab initio band structure calculations which are in good agreement with the measured photoemission data when assuming an antiferromagnetic ground state. Calculations for the ferromagnetic phase show a much smaller band gap, indicating the importance of possible ferromagnetic contributions for the explanation of the colossal magnetoresistance effect in the related ${\mathrm{EuZn}}_2{\mathrm{P}}_2$.

The antiferromagnetic ordering that MnBi${}_2$Te${}_4$ shows makes it invariant with respect to the combination of the time-reversal and primitive-lattice translation symmetries, giving rise to its topologically nontrivial nature and a number of fundamental phenomena. At the same time, the possibility to control the electronic and magnetic properties of this system can provide new effective ways for its application in devices. One of the approaches to manipulate MnBi${}_2$Te${}_4$ properties is the partial substitution of magnetic atoms in the compound with atoms of non-magnetic elements, which inevitably affect the interplay of magnetism and band topology in the system. In this work, we have carried out theoretical modelling of changes in the electronic structure that occur as a result of increasing the concentration of Sn atoms at Mn positions in the (Mn${}_{1-x}$Sn${}_x$)Bi${}_2$Te${}_4$ compound both using Korringa–Kohn–Rostoker (KKR) Green’s function method as well as the widespread approach of using supercells with impurity in DFT methods. The calculated band structures were also compared with those experimentally measured by angle-resolved photoelectron spectroscopy (ARPES) for samples with x values of 0, $0.19$, $0.36$, $0.52$ and $0.86$. We assume that the complex hybridization of Te-p${}_z$ and Bi-p${}_z$ orbitals with Sn and Mn ones leads to a non-linear dependence of band gap on Sn content in Mn positions, which is characterized by a plateau with a zero energy gap at some concentration values, suggesting possible topological phase transitions in the system.

Modification of the electronic and crystal structure of zero-layer graphene grown on $6H$-SiC(0001) after Co intercalation is reported. Using a wide range of techniques including angle-resolved photoelectron spectroscopy, x-ray photoelectron spectroscopy, Raman spectroscopy, low-energy electron diffraction, we found that zero-layer graphene on SiC transforms into graphene monolayer as a result of cobalt intercalation. The Dirac cone of $\pi$ band characteristic of quasi-freestanding graphene is observed. In combination with high-resolution transmission electron microscopy and atomic force microscopy data, we conclude that ultrathin silicide $\mathrm{CoSi}\text{/}{\mathrm{CoSi}}_2$ structure is formed between graphene and SiC substrate. Investigation of magnetic properties reveals ferromagnetic behavior with open hysteresis loop. The results of this work are the basis for further implementation of magneto-spin-orbit graphene on a semiconducting substrate and are important for the future application of such graphene in spintronics.

Using photoelectron diffraction and spectroscopy, we explore the structural and electronic properties of the hexagonal boron nitride $(h$-BN) monolayer epitaxially grown on the Co(0001) surface. Perfect matching of the lattice parameters allows formation of a well-defined interface where the B atoms occupy the hollow sites while the N atoms are located above the Co atoms. The corrugation of the $h$-BN monolayer and its distance from the substrate were determined by means of R-factor analysis. The obtained results are in perfect agreement with the density functional theory (DFT) predictions. The electronic structure of the interface is characterized by a significant mixing of the $h$-BN and Co states. Such hybridized states appear in the $h$-BN band gap. This allows to obtain atomically resolved scanning tunneling microscopy (STM) images from the formally insulating 2D material being in contact with ferromagnetic metal. The STM images reveal mainly the nitrogen sublattice due to a dominating contribution of nitrogen orbitals to the electronic states at the Fermi level. We believe that the high quality, well-defined structure and interesting electronic properties make the $h$-BN/Co(0001) interface suitable for spintronic applications.