Spin density wave instability in a ferromagnet

Fluctuation-driven topological Hall effect in room-temperature itinerant helimagnet Fe3Ga4

The topological Hall effect (THE) is a hallmark of a non-trivial geometric spin arrangement in a magnetic metal, originating from a finite scalar spin chirality (SSC). The associated Berry phase is often a consequence of non-coplanar magnetic structures identified by multiple k-vectors. For single - k magnetic structures however with zero SSC, the emergence of a finite topological Hall signal presents a conceptual challenge. Here, we report that a fluctuation-driven mechanism involving chiral magnons is responsible for the observed THE in a low-symmetry compound, monoclinic Fe3Ga4. Through neutron scattering experiments, we discovered several nontrivial magnetic phases in this system. In our focus is the helical spiral phase at room temperature, which transforms into a transverse conical state in applied magnetic field, supporting a significant THE signal up to and above room temperature. Our work offers a fresh perspective in the search for novel materials with intertwined topological magnetic and transport properties.

Deoxynivalenol and its modified forms: key enzymes, inter-individual and interspecies differences in metabolism

Deoxynivalenol (DON) and its modified forms, including DON-3-glucoside (DON-3G), pose a major agricultural and food safety issue in the world. Their metabolites are relatively well-characterized; however, their metabolizing enzymes have not been fully explored. UDP-glucuronosyltransferases, 3-O-acetyltransferase, and glutathione S-transferase are involved in the formation of DON-glucuronides, 3-acetyl-DON, and DON-glutathione, respectively. There are interindividual differences in the metabolism of these toxins, including variation with respect to sex. Furthermore, interspecies differences in DON metabolism have been revealed, including differences in the major metabolites of DON, the role of de-acetylation, and the hydrolysis of DON-3G. In this review, we summarized the major enzymes involved in metabolizing DON to its modified forms, focusing on the differences in metabolism of DON and its modified forms between individuals and species. This work provides important insight into the toxicity of DON and its derivatives in humans and animals, and provides scientific basis for the development of safer and more efficient biological detoxification methods.

Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn1− x (Co,Rh) x Ge

The search and exploration of new materials not found in nature is one of modern trends in pure and applied chemistry. In the present work, we report on experimental and ab initio density-functional study of the high-pressure-synthesized series of compounds Mn1− x (Co,Rh) x Ge. These high-pressure phases remain metastable at normal conditions, therewith they preserve their inherent noncentrosymmetric B20-type structure and chiral magnetism. Of particular interest in these two isovalent systems is the comparative analysis of the effect of 3d (Co) and 4d (Rh) substitution for Mn, since the 3d orbitals are characterized by higher localization and electron interaction than the 4d orbitals. The behavior of Mn1− x (Co,Rh) x Ge systems is traced as the concentration changes in the range 0 ≤ x ≤ 1. We applied a sensitive experimental and theoretical technique which allowed to refine the shape of the temperature dependencies of magnetic susceptibility χ(T) and thereby provide a new and detailed magnetic phase diagram of Mn1− x Co x Ge. It is shown that both systems exhibit a helical magnetic ordering that very strongly depends on the composition x. However, the phase diagram of Mn1− x Co x Ge differs from that of Mn1− x Rh x Ge in that it is characterized by coexistence of two helices in particular regions of concentrations and temperatures.