104 research outputs found
Theoretical and experimental study of high-pressure synthesized B20-type compounds Mn(Co,Rh)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 \textit{ab initio} density-functional study of the
high-pressure-synthesized series of compounds Mn(Co,Rh)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 (Co) and (Rh) substitution for
Mn, since the orbitals are characterized by higher localization and
electron interaction than the orbitals. The behavior of
Mn(Co,Rh)Ge systems is traced as the concentration changes in the
range . We applied a sensitive experimental and theoretical
technique which allowed to refine the shape of the temperature dependencies of
magnetic susceptibility and thereby provide a new and detailed
magnetic phase diagram of MnCoGe. It is shown that both systems
exhibit a helical magnetic ordering that very strongly depends on the
composition . However, the phase diagram of MnCoGe differs from
that of MnRhGe in that it is characterized by coexistence of two
helices in particular regions of concentrations and temperatures.Comment: 12 pages, 11 figure
Magnetic ground state and spin fluctuations in MnGe chiral magnet as studied by Muon Spin Rotation
We have studied by muon spin resonance ({\mu}SR) the helical ground state and
fluctuating chiral phase recently observed in the MnGe chiral magnet. At low
temperature, the muon polarization shows double period oscillations at short
time scales. Their analysis, akin to that recently developed for MnSi [A. Amato
et al., Phys. Rev. B 89, 184425 (2014)], provides an estimation of the field
distribution induced by the Mn helical order at the muon site. The refined muon
position agrees nicely with ab initio calculations. With increasing
temperature, an inhomogeneous fluctuating chiral phase sets in, characterized
by two well separated frequency ranges which coexist in the sample. Rapid and
slow fluctuations, respectively associated with short range and long range
ordered helices, coexist in a large temperature range below T = 170 K. We
discuss the results with respect to MnSi, taking the short helical period,
metastable quenched state and peculiar band structure of MnGe into account.Comment: 13 pages, 11 figure
Knowledge distillation for quality estimation
Quality Estimation (QE) is the task of automatically predicting Machine Translation quality in the absence of reference translations, making it applicable in real-time settings, such as translating online social media conversations. Recent success in QE stems from the use of multilingual pre-trained representations, where very large models lead to impressive results. However, the inference time, disk and memory requirements of such models do not allow for wide usage in the real world. Models trained on distilled pre-trained representations remain prohibitively large for many usage scenarios. We instead propose to directly transfer knowledge from a strong QE teacher model to a much smaller model with a different, shallower architecture. We show that this approach, in combination with data augmentation, leads to light-weight QE models that perform competitively with distilled pre-trained representations with 8x fewer parameters
Magnetic, electronic, and transport properties of the high-pressure-synthesized chiral magnets Mn1-xRhxGe
We report on the structural, magnetic, and transport properties of a set of high-pressure-synthesized compounds Mn1-xRhxGe (0≤x≤1) with chiral magnetic ordering. The magnetic and transport properties depend substantially on the concentration of rhodium (x) and the pressure. The saturation magnetic moment corresponds to a known high-spin value for pristine MnGe (x=0) and decreases almost linearly with increasing concentration x. In addition, x-ray magnetic circular dichroism spectra taken at 10 K and 2 T indicate magnetic polarization of the Rh 4d electron states and Ge 4p states, which decreases with x, too. In rhodium-rich compounds (x≥0.5), the temperature of the magnetic ordering increases significantly with pressure, whereas in manganese-rich compounds (x<0.5) the temperature decreases. Three different tendencies are also found for several structural and transport properties. In the intermediate range (0.3≤x≤0.7), samples are semiconducting in the paramagnetic phase, but they become metallic in the magnetically ordered state. We carried out ab initio density-functional calculations of Mn1-xRhxGe at various concentrations x and traced the evolution of the electronic and magnetic properties. The calculation results are in good agreement with the measured magnetic moments and qualitatively explain the observed trends in transport properties. © 2018 American Physical Society
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