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The area affected by the earthquake is vast and often difficult to entirely cover, and the earthquake itself is a sudden event that causes multiple defects simultaneously, that cannot be effectively traced using traditional, manual methods. This article presents an innovative approach to the problem of detecting damage after sudden events by using an interconnected set of deep machine learning models organized in a single pipeline and allowing for easy modification and swapping models seamlessly. Models in the pipeline were trained with a synthetic dataset and were adapted to be further evaluated and used with unmanned aerial vehicles (UAVs) in real-world conditions. Thanks to the methods presented in the article, it is possible to obtain high accuracy in detecting buildings defects, segmenting constructions into their components and estimating their technical condition based on a single drone flight., Comment: 15 pages, 8 figures, published version, software available from https://github.com/MatZar01/IC_SHM_P2

Magnetic skyrmions, which are topologically distinct magnetic spin textures, are gaining increased attention for their unique physical properties and potential applications in spintronic devices. Here we present a design strategy for skyrmion host candidates based on combinations of magnetic spin, asymmetric building units having stereo-active lone-pair electrons, and polar lattice symmetry. To demonstrate the viability of the proposed rational design principles, we successfully synthesized Fe(IO3)3 polycrystalline sample and single crystals by using a new simplified low-temperature pathway, which is experimentally feasible for extending materials growth of transition metal iodates. Single crystal X-ray and powder synchrotron X-ray diffraction measurements demonstrated that Fe(IO3)3 crystallizes in the polar chiral hexagonal lattice with space group P63. The combined structural features of the macroscopic electric polarization along the c axis stemming from the coalignment of the stereo-active lone-pairs of the IO3 trigonal pyramid and the magnetic Fe3+cation residing on the three-fold rotation axis were selected to promote asymmetric exchange coupling. We find evidence of a predicted skyrmion phase at 14 K to 16 K and 2.5 T to 3.2 T driven by Dzyaloshinskii Moriya (DM) interaction, a conclusion supported by the appreciable DM exchange and the zero-field spiral antiferromagnetic ground state of Fe(IO3)3 deduced from neutron diffraction experiments. The associated magnetic modulation wavelength of the putative skyrmions is expected to be short, approximately 18 nm, comparable to the period of the DM-driven incommensurate order. This work links stereo-active lone-pair electron effects to enhanced DM interaction, demonstrating a new approach for chemical guidelines in the search for skyrmionic states of matter.

The EuFe(2-x)Ni(x)As2 compounds exhibiting 3d and/or 4f magnetic order were investigated by means of 57Fe and 151Eu M\"ossbauer spectroscopy. Additionally, results for the end members of this system, i.e. EuFe2As2 and EuNi2As2, are reported for comparison. It was found that spin-density-wave order of the Fe itinerant moments is monotonically suppressed by Ni-substitution. However, the 3d magnetic order survives at the lowest temperature up to at least x = 0.12 and it is certainly completely suppressed for x = 0.20. The Eu localized moments order regardless of the Ni concentration, but undergo a spin reorientation with increasing x from the alignment parallel to the a-axis in the parent compound, toward c-axis alignment for x > 0.07. The change of the 4f spins ordering from antiferromagnetic to ferromagnetic takes place simultaneously with a disappearance of the 3d spins order what is the evidence of a strong coupling between magnetism of Eu2+ ions and the conduction electrons of [Fe(2-x)Ni(x)As2]2- layers. The Fe nuclei experience the transferred hyperfine magnetic field due to the Eu2+ ordering for Ni-substituted samples with x > 0.04, while the transferred field is undetectable in EuFe2As2 and for compound with a low Ni-substitution level. It seems that the 4f ferromagnetic component arising from a tilt of the Eu2+ moments to the crystallographic c-axis leads to the transferred magnetic field at the Fe atoms.

The BaFe2(As1-xPx)2 compounds with x = 0 (parent), x = 0.10 (under-doped), x = 0.31, 0.33, 0.53 (superconductors with Tc = 27.3 K, 27.6 K, 13.9 K, respectively) and x = 0.70, 0.77 (over-doped) have been investigated versus temperature using 57Fe M\"ossbauer spectroscopy. Special attention was paid to regions of the spin-density-wave (SDW) antiferromagnetic order, spin-nematic phase, and superconducting transition. The BaFe2(As0.90P0.10)2 compound exhibits a reduced amplitude of SDW as compared to the parent compound and preserved universality class of two-dimensional magnetic planes with one-dimensional spins. The spin-nematic phase region for x = 0.10 is characterized by an incoherent magnetic order. BaFe2(As0.69P0.31)2 shows coexistence of a weak magnetic order and superconductivity due to the vicinity of the quantum critical point. The charge density modulations in the BaFe2(As0.67P0.33)2 and BaFe2(As0.47P0.53)2 superconductors are perturbed near Tc. Pronounced hump of the average quadrupole splitting across superconducting transition is observed for the system with x = 0.33. The phosphorus substitution increases the Debye temperature of the BaFe2(As1-xPx)2 compound. Moreover, experimental electron charge densities at Fe nuclei in this material conclusively show that it should be recognized as a hole-doped system. The measured M\"ossbauer spectral shift and spectral area are not affected by transition to the superconducting state. This indicates that neither the average electron density at Fe nuclei nor the dynamical properties of the Fe-sublattice in BaFe2(As1-xPx)2 are sensitive to the superconducting transition. Theoretical calculations of hyperfine parameters determining the patterns of M\"ossbauer spectra of BaFe2(As1-xPx)2 with x = 0, 0.31, 0.5, and 1.0 are performed within the framework of the density functional theory.

57Fe and 151Eu Moessbauer spectra were obtained versus temperature for Eu0.57Ca0.43Fe2As2 compound with 3d and 4f magnetic order and Eu0.73Ca0.27(Fe0.87Co0.13)2As2 re-entrant superconductor, where the finite resistivity reappears while approaching the ground state. They were compared with previously obtained spectra for parent compounds EuFe2As2 and CaFe2As2. It was found that substitution beyond the Fe-As layers does not lead to the rotation (canting) of the Eu2+ magnetic moments and does not generate Eu3+ states. On the other hand, re-entrant superconductor exhibits rotation (canting) of the Eu2+ moments on the c-axis of the unit cell leading to the transferred hyperfine magnetic field on iron nuclei. Divalent europium orders magnetically within the bulk of the re-entrant superconducting phase. The re-entrant superconductor remains in the inhomogeneous state close to the ground state with about 27 % of the volume being free of 3d magnetism, while the remainder exhibits weak spin density wave. Those two regions slightly differ by the electric field gradient and electron density on iron nuclei.

Moessbauer spectroscopy measurements were performed for the temperature range between 4.2 K and 300 K in a transmission geometry applying 14.41-keV resonant line in 57Fe for PrFeAsO the latter being a parent compound of the iron-based superconductors belonging to the '1111' family. It was found that an itinerant 3d magnetic order develops at about 165 K and it is accompanied by an orthorhombic distortion of the chemical unit cell. A complete longitudinal 3d incommensurate spin density wave (SDW) order develops at about 140 K. Transferred hyperfine magnetic field generated by the praseodymium magnetic order on iron nuclei is seen at 12.8 K and below, i.e., below magnetic order of praseodymium magnetic moments. It is oriented perpendicular to the field of SDW on iron nuclei. The shape of SDW is almost rectangular at low temperatures and it transforms into roughly triangular form around 'nematic' transition at about 140 K. Praseodymium magnetic order leads to the substantial enhancement of SDW due to the large orbital contribution to the magnetic moment of praseodymium. A transferred field indicates presence of strong magnetic susceptibility anisotropy in the [b-c] plane while following rotation of praseodymium magnetic moments in this plane with lowering temperature. It was found that 'nematic' phase region is a region of incoherent spin density wavelets typical for a critical region.

Transmission M\"ossbauer spectra for 14.41-keV transition in 57Fe were obtained for chalcopyrite-type (Cu-Fe-S2) ternary nanocrystals stabilized by long aliphatic chain ligands. These systems could be considered as isolated hard nano-objects dispersed in soft network of organic ligands. The main attention was paid to the behavior of the particles whose average size was varied in a controllable manner from 3 to 20 nm. It was found that the magnetic hyperfine interaction was relaxed to null to the temperatures well below liquid nitrogen temperature due to the isolation of particles. The fast dynamics could be described by two level environment. Deeper level (atomic) was practically the same as for bulk material except Debye temperature, but the higher level (particle motion) was described by the classical harmonic oscillator with the spring constant dramatically softening with increasing temperature. Such behavior led to fast decrease of the recoilless fraction with increasing temperature. Practically no spectra could be obtained above 240 K. The second order Doppler shift (SOD) had additional contribution at elevated temperatures due to the induced internal oscillations within particle by surrounding thermal bath. Slow dynamics was characterized by the thermally driven overdamped harmonic oscillator motions. In addition, the long range like diffusion of particles was seen. No significant rotation of particles was found within accessible temperature range., Comment: 14 pages, 7 figures

The paper deals with the hyperfine interactions observed on the 57Fe nucleus in multiferroic BiFeO3 by means of the 14.41-keV resonant transition in 57Fe, and for transmission geometry applied to the random powder sample. Spectra were obtained at 80 K, 190 K and at room temperature. It was found that iron occurs in the high spin trivalent state. Hyperfine magnetic field follows distribution due to the elliptic-like distortion of the magnetic cycloid. The long axis of the ellipse is oriented along <111> direction of the rhombohedral unit cell. The hyperfine magnetic field in this direction is about 1.013 of the field in the perpendicular direction at room temperature. This ratio diminishes to 1.010 at 80 K. Axially symmetric electric field gradient (EFG) on the iron atoms has the principal axis oriented in the same direction and the main component of the EFG is positive. Our results are consistent with the finding that iron magnetic moments are confined to the [1-21] crystal plane.

Moessbauer transmission spectra for the 14.41-keV resonant line in 57Fe have been collected at room temperature by using 57Co(Rh) commercial source and alpha-Fe strain-free single crystal as an absorber. The absorber was magnetized to saturation in the absorber plane perpendicular to the gamma-ray beam axis applying small external magnetic field. Spectra were collected for various orientations of the magnetizing field, the latter lying close to the [110] crystal plane. A positive electric quadrupole coupling constant was found practically independent on the field orientation. One obtains the following value Vzz=+1.61(4)x10^19 V/m^2 for the (average) principal component of the electric field gradient (EFG) tensor under assumption that the EFG tensor is axially symmetric and the principal axis is aligned with the magnetic hyperfine field acting on the 57Fe nucleus. The nuclear spectroscopic electric quadrupole moment for the first excited state of the 57Fe nucleus was adopted as +0.17 b. Similar measurement was performed at room temperature using as-rolled polycrystalline alpha-Fe foil of high purity in the zero external field. Corresponding value for the principal component of the EFG was found as Vzz=+1.92(4)x10^19 V/m^2. Hence, it seems that the origin of the EFG is primarily due to the local (atomic) electronic wave function distortion caused by the spin-orbit interaction between effective electronic spin S and incompletely quenched electronic angular momentum L. It seems as well that the lowest order term proportional to the product L.LAMBDA.S dominates, as no direction dependence of the EFG principal component is seen. The lowest order term is isotropic for a cubic symmetry as one has LAMBDA=lambda.1 for cubic systems with the symbol 1 denoting unit operator and lambda being the coupling parameter.

Iron-based superconductor SmFeAsO(0.91)F(0.09) has been investigated by the 57Fe Moessbauer spectroscopy versus temperature with the special attention paid to the region of the superconducting transition at about 47 K. Modulation of the electron charge density was found. It leads to the development of the charge density wave (CDW) and electric field gradient wave (EFGW). The modulation of CDW is enhanced in the temperature region of the superconducting gap opening, while the amplitude of EFGW is partly suppressed within this temperature region. This effect is exactly opposite to the similar effect in Ba(0.6)K(0.4)Fe2As2 superconductor. Hence, it seems that d electrons contribute significantly to the Cooper pair formation in both compounds as EFGW is perturbed within the temperature region of the superconducting gap formation.

Two iron-chalcogenide superconductors Li(x)[C5H5N](y)Fe(2-z)Se2 and Cs(x)Fe(2-z)Se2 in the as-prepared and annealed state have been investigated by means of the Moessbauer spectroscopy versus temperature. Multi-component spectra are obtained. One can see a non-magnetic component due to iron located in the unperturbed Fe-Se sheets responsible for superconductivity. Remaining components are magnetically ordered even at room temperature. There is some magnetically ordered iron in Fe-Se sheets perturbed by presence of the iron vacancies. Additionally, one can see iron dispersed between sheets in the form of magnetically ordered high spin trivalent ions, some clusters of above ions, and in the case of pyridine intercalated compound in the form of alpha-Fe precipitates. Pyridine intercalated sample shows traces of superconductivity in the as-prepared state, while cesium intercalated sample in the as-prepared state does not show any superconductivity. Superconductors with transition temperatures being 40 K and 25 K, respectively, are obtained upon annealing. Annealing leads to removal/ordering of the iron vacancies within Fe-Se sheets, while clusters of alpha-Fe grow in the pyridine intercalated sample.