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3 Acta Physica Polonica A

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NMR (^{55}Mn, ^{139}La) and Mössbauer Spectroscopy (^{119}Sn) Studies of (La_{0.67}Ca_{0.33})(Mn_{1-x}Sn_x)O_{3-δ} Compounds

100%

Przewoźnik J.

nr 5

649-659

A ^{119}Sn Mössbauer spectroscopy and zero field ^{55}Mn and ^{139}La NMR studies of (La_{0.67}Ca_{0.33})(Mn_{1-x}Sn_x)O_{3-δ} (x=0, 0.01, 0.03, andδ≈0.06) were reported. The temperature evolution of the Sn hyperfine field (B_{hf}) for x=0.03 determined from the Mössbauer spectroscopy measurements was analysed within a molecular field model. A fit to the temperature dependence of B_{hf}^{max} provided the Curie temperature T^*_C=160(3) K, which is in good agreement with T_C obtained from dc magnetisation measurements. The ^{55}Mn NMR spectra for $x=0$ and 0.01 show a single double exchange Mn^{3+/4+} resonance line and exhibit strong Suhl-Nakamura relaxation effects characteristic of the ferromagnetic metallic phase. The spectra for x=0.03 show a coexistence of the double exchange line with the lines characteristic of Mn^{3+} and Mn^{4+} valence states. This shows that a 3% Sn doping strongly suppresses the double exchange interaction and leads to microscopic phase segregation into ferromagnetic metal and ferromagnetic insulator.

Magnetism and Specific Heat of TmRhX (X = Ga, Ge) Compounds

51%

Baran S. , Przewoźnik J. , Szytuła A.

nr 6

998-1001

Magnetic and specific heat data of the TmRhX (X = Ga, Ge) compounds are reported. These compounds crystallize in an orthorhombic crystal structure of the TiNiSi-type (space group Pnma). Magnetic data indicate that the compounds are antiferromagnets with the Néel temperature T_{N} equal to 3.9 K for TmRhGa and 6.0 K for TmRhGe. Magnetic susceptibility of TmRhGe has an additional peak at T_{t} = 10.6 K. In TmRhGe temperature dependence of χ"(T), the positions of both the peaks at T_{N} and T_{t} change with frequency indicating a relaxation process. These data suggest that with the decreasing temperature, first a cluster glass state and next the long-range aniferromagnetic order exists.

Ion Irradiation of Oxidized FeCoZr-CaF₂ Nanocomposite Films for Perpendicular Magnetic Anisotropy Enhancement

32%

Kasiuk J. , Fedotova J. , Przewoźnik J. , Kapusta C. , Skuratov V. , Svito I. , Bondariev V. , Kołtunowicz T.

Acta Physica Polonica A

2017

tom 132

nr 2

206-209

The paper is focused on the results of Xe ions irradiation of nanocomposite FeCoZr-CaF₂ films synthesized in the oxygen-containing atmosphere. Combined influence of nanoparticles partial oxidation and ion irradiation with different fluences on the crystalline structure, phase composition and magnetic anisotropy is analysed by X-ray diffraction, the Mössbauer spectroscopy and vibrating sample magnetometry. The origin of the detected progressive enhancement of perpendicular magnetic anisotropy as the result of films oxidation and irradiation is discussed in the context of formation of nanoparticles oxide shells and ion tracks along the films normal.