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تسجيل مستخدم جديدTheoretical and experimental study of high-pressure synthesized B20-type compounds Mn$_{1-x}$(Co,Rh)$_x$Ge
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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 textit{ab initio} density-functional study of the high-pressure-synthesized series of compounds Mn$_{1-x}$(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 Mn$_{1-x}$(Co,Rh)$_x$Ge systems is traced as the concentration changes in the range $0 leq x leq 1$. We applied a sensitive experimental and theoretical technique which allowed to refine the shape of the temperature dependencies of magnetic susceptibility $chi(T)$ and thereby provide a new and detailed magnetic phase diagram of Mn$_{1-x}$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 Mn$_{1-x}$Co$_x$Ge differs from that of Mn$_{1-x}$Rh$_x$Ge in that it is characterized by coexistence of two helices in particular regions of concentrations and temperatures.
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We report on structural, magnetic and transport properties of a new set of the high-pressuresynthesized compounds Mn$_{1-x}$Rh$x$Ge ($0 leq x leq 1$) with the chiral magnetic ordering. The magnetic and transport properties depend substantially on the
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We present ab initio density-functional study of the noncentrosymmetric B20-type phase of RhGe, which is not found in nature and can be synthesized only at extreme pressures and temperatures. The structural, thermodynamic, electronic, lattice-dynamic
al, and transport properties of B20-RhGe are calculated, and their evolution with increasing pressure is traced. The temperature dependence of the charge and heat transport properties is evaluated within the semi-classical Boltzmann approach. Using the quasi-harmonic approximation, we determine the range of pressures and temperatures, in which B20-RhGe is stable, and make recommendations for optimizing the synthesis conditions in order to reduce the number of defects that occur in a sample during solidification.
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