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• Pure and homogeneous MnSi is obtained via arc melting and post-annealing. • MnSi polycrystals show typical magnetic transitions as observed in single crystals. • Magnetic skyrmions can be identified in polycrystalline MnSi using magnetometry. We employed x-ray diffractometer, electron microscope and magnetometer to study the structure and magnetic properties of polycrystalline MnSi. Pure and homogeneous MnSi phase can be obtained in a certain composition range. Intriguingly, our magnetic measurements indicate that the polycrystalline MnSi shows typical magnetic phase transitions as single crystals. The magnetic transformations between helical, conical, skyrmion and field-polarized states can be well detected in the field-dependent susceptibility curves. The similar magnetic behaviors observed for polycrystalline and single crystals make magnetometry an effective and straightforward route to identify skyrmions, especially useful for the materials that are hard to prepare single crystals or epitaxial thin films. [ABSTRACT FROM AUTHOR]

Highlights • Synthesis time of (Mn,Fe) 2 (P,Si) alloys is greatly shortened using the new method. • Samples using industrial-grade raw materials show superior magnetocaloric property. • Fe 3 Si-type impurity phase in the as-prepared sample is eliminated by post annealing. Abstract We have demonstrated a time-, energy-, and cost-efficient way of preparing (MnFe) 2 (P,Si)-type magnetocaloric materials, i.e. , via electromagnetic levitation melting and post-annealing from industrial-grade starting materials. The structural evolution and its influence on the magnetocaloric properties during post-annealing have been intensively studied. We found that some Fe 3 Si-type impurity phase with a size of around 5 μm is present in the as-prepared sample, which can be eliminated through high-temperature annealing. The sample annealed at 1373 K for 5 h shows a homogeneous element distribution and negligible amount of the impurity phase. A Δ S max value of 17 Jkg−1 K−1 for a field change of 2 T has be realized in the present work, which is comparable to the highest Δ S max values in the (MnFe) 2 (P,Si)-type samples produced via time- and energy-consuming solid-state reaction. [ABSTRACT FROM AUTHOR]

Electron paramagnetic resonance (EPR) was applied extensively to probe the phase separation and spin relaxation mechanism in the perovskite manganites. In this study, we conducted the measurement of EPR for the perovskite manganites (La 0.5 Pr 0.5 ) 0.67 Ca 0.33 MnO 3 . We found that both paramagnetic and ferromagnetic resonance peaks simultaneously emerged on resonance spectrum near below T C , exhibiting a typical characteristic of phase separation. The linewidth of EPR spectrum progressively enlarged upon the rising of temperature in the temperature range of T > T C and a quasilinear variation of peak-peak width was observed at T C < T < 500 K. In contrast to the usual beliefs that the variation of peak-peak linewidth can be understood either by spin-lattice relaxation or by spin-spin relaxation, however, the linewidth behavior observed here shows a coexistence of two spin relaxation mechanisms. We proposed that the inhomogeneous electronic phases due to the intrinsic self-organizing growth were responsible for the appearance of multiple spin exchange interactions and variational relaxation mechanism. This finding would be possible to pave a new way for further investigating magnetic correlations and spin dynamics in the paramagnetic hole-doped manganites. [ABSTRACT FROM AUTHOR]

• The critical behavior of (Ce 0.65 Pr 0.35) 2 Co 7 alloy has been clarified with different methods. • The accurate Curie temperature of 214 K has been confirmed by the Arrott plot and ac magnetic susceptibility. • The magnetic coupling of (Ce 0.65 Pr 0.35) 2 Co 7 alloy belongs to long-range FM interaction. Clarification of magnetic phase transition nature and critical behavior is an essential step in the development of new magnetic functional materials. In this work, we studied critical properties of intermetallic compound (Ce 0.65 Pr 0.35) 2 Co 7 by bulk dc magnetization around the paramagnetic to ferromagnetic phase transition. It exhibits a second-order magnetic phase transition with T C = 214 K. Critical exponents β = 0.546(5) and γ = 1.054(5) are obtained by the modified Arrott plot, whereas δ = 2.843 is obtained by a critical isotherm analysis at T C. These critical exponents not only obey the Widom relation δ = 1 + γ / β , but also collapse the isothermal magnetization M-H-T data into two branches below and above T C following the single scaling equation M(H, ε) = ε β f ± (H/ ε β + γ ). Although the obtained exponents are close to the theoretical values of mean-field model, a noticeable deviation unable to be ignored, indicating the existence of localized magnetic interaction which competes with a long-range ferromagnetic state. Our results will establish a sound theoretical basis for understanding the complex magnetic interaction in the light rare earths ternary alloy. [ABSTRACT FROM AUTHOR]