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1
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Development of Magnetic Properties during Annealing of Hf₂Co₁₁B Amorphous Alloy

100%
Musiał A., Śniadecki Z., Idzikowski B.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
786-788
EN
Influence of heat treatment on magnetic properties of amorphous Hf₂Co₁₁B alloy was investigated. Hard magnetic phase, characterized by high magnetic anisotropy, appears during crystallization. The highest coercive field equal to 1.86 kOe, was obtained for sample annealed in third crystallization stage. Longer heat treatment at T_{a} = 650°C leads to decrease in coercive field, which can be the result of excess of the HfCo₃B₂ phase volume fraction and additionally eutectoid transformation of hard magnetic phase into soft magnetic Co₂₃B₆ and fcc-Co. Decrease of volume fraction of hard phase is confirmed by the remanence ratio m_{r}. Value of m_{r}, for T_{a} = 650°C, is decreasing with annealing time from 0.4 to 0.27 for 30 min and 120 min, respectively. The magnetocrystalline anisotropy constant K₁ increases from 2.23 Merg/cm³ for the amorphous ribbon to 15.84 Merg/cm³ for the sample annealed at 650°C for 30 min.
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Crystallisation of Amorphous Y rm_{50}Cu_{42}Al_8 Alloy

100%
Idzikowski B., Śniadecki Z., Mielniczuk B.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
147-149
EN
Amorphous Y_{50}Cu_{42}Al_8 ribbon was prepared by melt-spinning technique on the Cu wheel. The crystallisation process was analysed by differential scanning calorimetry and X-ray diffraction. Differential scanning calorimetry curves characterising two crystallisation stages of Y_{50}Cu_{42}Al_8 alloy were measured in non-isothermal dynamic mode at different heating rates. Activation energies of both steps of crystallisation process were acquired by the Kissinger method and are equal to 570± 56 and 290±29 kJ/mol for the first and second stage, respectively. By annealing the ribbon at a given temperature for various times the nanocrystalline phase grains of the sizes of about 40 nm in diameter were created. The influence of the annealing temperature on the grain size evolution was also examined.
3
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Semi-Empirical Modelling of Glass Forming Ranges for Y-Co-Si System

100%
Śniadecki Z., Narojczyk J., Idzikowski B.
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vol. 126
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issue 1
62-63
EN
Glass forming abilities of a ternary Y-Co-Si system were determined on the basis of combined semi-empirical Miedema's and geometric models. The enthalpy of amorphous and solid solution phases formation, along with the mismatch entropy and GFA parameter, were analysed to indicate compositions with the highest ability for the amorphization. The large atomic radii difference between constituents, especially Y and Si, is the deciding factor of GFA. Compositions ranged between Y_{33}Si_{67} and Y_{45}Si_{55} are the best glass formers.
4
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Activation Energies of Crystallization in Amorphous RMn_{4.5}Ge_{4.5}Fe_{1.5}Al_{1.5} (R = La, Y, Dy) Alloys

100%
Śniadecki Z., Rößler U., Idzikowski B.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
409-412
EN
The effective activation energies, characteristic crystallization temperatures and enthalpies of amorphous RMn_{4.5}Ge_{4.5}Fe_{1.5}Al_{1.5} (R = Y, La, Dy) alloys produced using melt-spinning technique were investigated by differential scanning calorimetry. X-ray diffraction measurements were performed for as-quenched and annealed samples. The crystalline structure of annealed YMn_{4.5}Ge_{4.5}Fe_{1.5}Al_{1.5} and DyMn_{4.5}Ge_{4.5}Fe_{1.5}Al_{1.5} alloys was determined as orthorhombic TbFe_6Sn_6-type with Cmcm (63) space group. The alloy with Y appears as a more useful non-magnetic analogue for DyMn_{4.5}Ge_{4.5}Fe_{1.5}Al_{1.5} than the La-based alloy. The differential scanning calorimetry curves for Dy- and Y-based alloys also exhibit similar thermal behavior. The effective activation energies E_a were determined using the Kissinger approach and high values up to 778±74 kJ/mol for La-based sample were established. The comparison of Y-, La-, and Dy-based alloys suggests improvement of thermal stability with the increase in rare-earth element atomic radius in the glassy RMn_{4.5}Ge_{4.5}Fe_{1.5}Al_{1.5} systems.
5
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Crystallization Processes of R_{4.5}Fe_{77}B_{18.5} (R = Pr, Nd) Amorphous Alloys

100%
Musiał A., Śniadecki Z., Pagnani D., Idzikowski B.
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vol. 126
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issue 1
316-317
EN
The amorphous alloys R_{4.5}Fe_{77}B_{18.5} (R=Pr, Nd) were prepared by melt-spinning technique under argon atmosphere on a cooper wheel rotating with surface velocity of 25 m·s^{-1}. The ribbons have been investigated by means of X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Temperatures of crystallization for Pr_{4.5}Fe_{77}B_{18.5}, measured at the heating rate 20 K/min, are equal T_{x1}=591°C for the first exothermic effect and T_{x2}=603°C for the second one (for Nd_{4.5}Fe_{77}B_{18.5} T_{x1}=594°C and T_{x2}=633°C). In the amorphous ribbons the crystallization of Fe_{3}B phase in the first step, followed by the crystallization of Pr_{2}Fe_{23}B_{3} and Nd_{2}Fe_{23}B_{3}, was observed. Both later phases appear in the process of recrystallization, immediately after Fe_{3}B formation.
6
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Critical Behavior near the Ferromagnetic to Paramagnetic Phase Transition in Y₈Co₆₂B₃₀ Amorphous Alloy

100%
Śniadecki Z., Marcin J., Idzikowski B.
Acta Physica Polonica A
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2017
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vol. 131
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issue 4
967-969
EN
The Y₈Co₆₂B₃₀ amorphous alloy is a collinear ferromagnet. The Arrott plot, the Kouvel-Fisher method, critical isotherm analysis and magnetic field dependence of maximum magnetic entropy changes were the main analytical tools used to determine the nature of the ferromagnetic/paramagnetic phase transition. Values of critical exponents (β, γ, and δ) were calculated and were convergent with those characteristic for mean-field model. It suggests that long range ferromagnetic interactions are playing main role in investigated alloy and the phase transition was confirmed to be of a second order according to the Banerjee criterion.
7
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Correlation between Magnetic Phases and Insulator-Metal Transition in La_{1/3}Nd_{1/3}Ca_{1/3}MnO_{3} Perovskite

100%
Baszyński J., Idzikowski B., Toliński T., Hoser A.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
779-782
EN
The La_{1/3}Nd_{1/3}Ca_{1/3}MnO_{3} ceramic perovskites are investigated using the neutron diffraction technique and resistance measurements in the temperature range from 260 K down to 5 K. We have found that the integrated intensity of the antiferromagnetic peaks was growing with decreasing temperature and reached the maximum at a temperature about 20 K lower than that of the semiconductor-metal transition and did not vanish at 5 K. The semiconductor-metal transition is correlated with the temperature of the maximum of the lattice c-parameter and the percolation of ferromagnetic domains. Our results suggest that although the ferromagnetic long-range order is established through the semiconductor-metal transition induced percolation network, locally the antiferromagnetic correlation can remain.
8
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Nanocrystallization of the Amorphous Fe_{14}Ni_{40}Zr_7B_{12} Alloys Studied by the Mössbauer Spectroscopy

100%
Kopcewicz M., Idzikowski B., Kalinowska J.
Acta Physica Polonica A
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2002
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vol. 102
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issue 2
301-307
EN
Formation of the soft magnetic nanostructure in amorphous Fe_{41}Ni_{40}Zr_7B_{12} alloy due to heat treatment is studied by the Mössbauer, differential scanning calorimetry, and X-ray diffraction techniques. Annealing at temperatures 520-580ºC leads to the formation of extremely soft nanocrystalline alloy as revealed by the rf-Mössbauer measurements. The superparamagnetic behaviour was observed for the alloy annealed at 620-640ºC. At higher annealing temperatures good soft magnetic properties deteriorate.
9
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Neutron Diffraction Study of Ferromagnetic Ordering in La_{1/3}Nd_{1/3}Ca_{1/3}MnO_{3} Induced by Electric Field

100%
Baszyński J., Idzikowski B., Toliński T., Hoser A.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
831-834
EN
We used the neutron diffraction technique to study the ferromagnetic ordering process in La_{1/3}Nd_{1/3}Ca_{1/3}MnO_{3} induced by the short impulse of the external electric field E=4 V/cm at a magnetic field H=1.5 T. Our sample was prepared by the standard solid-state reaction. The diffraction measurements at 4 K, carried out for the neutron wavelength λ=0.2442 nm, have revealed the orthorhombic perovskite structure with the unit-cell parameters: a=0.5480 nm, b=0.5550 nm and c=0.7737 nm. We observed that a short impulse of the electric field develops the ferromagnetic ordering in a similar way as the magnetic field up to 4 T. We assume that the increased ferromagnetic ordering induced by the external electric field at a given magnetic field has the same physical origin as in the case of the Zener double exchange. The effect is confirmed by magnetic moment measurements using vibrating sample magnetometer.
10
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Crystalline Structure, Stoichiometry and Magnetic Properties of the Morasko Meteorite

88%
Idzikowski B., Kováč J., Diko P., Stankowski W., Muszyński A.
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issue 5
1071-1073
EN
The composition and structure of iron-nickel alloys smithereens extracted from the Morasko (Poland) Meteorite (fell ∿ 5 ka BP) were investigated by optical metallographic techniques, scanning electron microscopy and electron microprobe analysis, thermal analyses, magnetic measurements and X-ray diffraction. Microstructural analysis by scanning electron microscopy and optical microscopy has shown that the sample is composed from large grains of Fe-Ni alloy in which secondary phase crystals with well developed crystal habits and the size about 10 micrometers are distributed. Thermal analyses confirmed that the transformation from alpha to gamma Fe-Ni solid solution appearing as a function of temperature corresponds to about 5 wt% Ni in the Fe-Ni alloy. Possible scenario of the extraterrestrial sample solidification is related to the microstructural and magnetic behavior.
11
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Composition and Temperature Dependence of Giant Magnetoresistance in Melt-Spun Co_{x}Cu_{100-x} Ribbons

88%
Idzikowski B., Nenkov K., Handstein A., Hütten A., Müller K.-H.
Acta Physica Polonica A
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1997
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vol. 92
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issue 2
307-310
EN
Structure, magnetic properties and magnetoresistance in as-quenched and annealed Co_{x}Cu_{100-x} samples were investigated. Homogeneous metastable Co_{x}Cu_{100-x} alloys were prepared by the single-roller technique. The maximum value of magnetoresistance is shifted to higher annealing temperatures with increasing measuring temperature. At higher measuring temperatures the magnetoresistance is not saturated in fields as high as 16 T. Susceptibility measurements showed the formation of hcp-structured Co clusters. For small cobalt concentrations there is a transition from giant magnetoresistance to the normal anisotropic magnetoresistance.
12
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Giant Magnetoresistance in Melt-Spun Co-Cu Modified by Rare Earths

88%
Idzikowski B., Rössler U., Handstein A., Nenkov K., Müller K.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
791-794
EN
Samples of the composition RE_{x}Co_{20}Cu_{80-x}, RE = Sm, Gd or Dy (x = 0, 1, and 3) were produced by melt-spinning and subsequent annealing. The magnetoresistance is negative as in granular Co-Cu, but its values depend on the kind of rare earth element added and on changes in the microstructure induced by thermal annealing. An addition of 1 at.% rare earth metal to Co_{20}Cu_{80} yields a considerable increase in the magnetoresistance ratio, whereas an addition of 3 at.% causes a decrease. E.g., by addition of 1 at.% Dy to Co_{20}Cu_{80} and optimal thermal treatment, the value of magnetoresistance ratio measured at 10 K in a field of 5 T increases from -14% to -28%. The effect can be attributed to the presence of clusters of hexagonal Dy(Co,Cu)_{5}, which was ascertained from X-ray diffraction data, or other, metastable rare-earth compounds and paramagnetic rare-earth atoms in the Cu matrix.
13
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Conductance Quantization in the Melt-Spun Cubic RCu_5 (R = Gd, Ho, Lu) Nanowires

88%
Szorcz M., Susła B., Wawrzyniak M., Lipiński S., Idzikowski B.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
165-167
EN
Conductance quantization of heterocontacts between tungsten (W) tip and cubic RCu_5 (R = Gd, Ho, Lu) binary compounds prepared by melt-spinning was observed in nanowires produced dynamically using piezoelectric actuator. The conductance stepwise behaviour of the nanowires was directly observed with a storage oscilloscope. Quantum units of the nanowires conductance measured in their paramagnetic states are presented and discussed in terms of the Landauer formalism.
14
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Current-Voltage Characteristics of Nanowires Formed at the Co-Ge_{99.99}Ga_{0.01} Interface

88%
Wawrzyniak M., Maćkowski M., Śniadecki Z., Idzikowski B., Martinek J.
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issue 2
375-378
EN
We present a method of measurement of the current-voltage (I-V) and conductance-voltage (G-V) characteristics of nanowires with quantum point contact formed at the Co-Ge_{99.99}Ga_{0.01} interface. The effect of the Fermi level pinning leads to the formation of an ohmic contact between Co and Ge_{99.99}Ga_{0.01}. On the measured characteristics, above the threshold value of voltage an exponential current growth is observed. Such effect could be useful in the production of the electronic nanodevices.
15
Content available remote

Electron Transport and Point Contact Spectroscopy of Cubic DyCu_{5}

76%
Nenkov K., Idzikowski B., Ilkovic S., Kačmarčiková E., Reiffers M., Müller K.
Acta Physica Polonica A
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2000
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vol. 97
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issue 5
843-846
EN
The electron transport properties and point contact spectra of melt-spun DyCu_{5} with the cubic phase (structure type AuBe_{5}, space group $F\overline{4}3m$) were investigated. It was found by ac-susceptibility measurements that below a transition temperature T_{m}=6.5 K this phase shows metamagnetism. Between T_{m} and T_{C}=14.5 K a spontaneous magnetization is found. Our measurements of electrical resistivity confirm the existence of two magnetic phase transitions in the compound. Furthermore, we present point contact spectra of DyCu_{5}-Cu heterocontacts which are directly proportional to the electron-quasiparticle interaction function. Apart from a peak at about 18 meV, which is characteristic of electron-phonon interaction in pure Cu, we observed a series of additional maxima at lower energy, which are connected with the allowed 4f-transitions from the ground state to excited crystalline electric field levels.
16
Content available remote

Magnetic Properties and Structure of Amorphous Fe_{74}Hf_{4}Ta_{1}Cu_{1}Gd_{1}La_{x}Si_{15-x}B_{4} (x = 0, 7) Ribbons

76%
Bardziński P., Kopcewicz M., Rybaczuk M., Hasiak M., Musiał A., Kinzhybalo V., Idzikowski B.
Acta Physica Polonica A
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2015
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vol. 127
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issue 3
827-830
EN
The multi component Fe_{74}Hf_{4}Ta_{1}Cu_{1}Gd_{1}La_{x}Si_{15-x}B_{4} (x = 0, 7) alloys are promising candidates in the search for materials with unusual mechanical and magnetic properties. Amorphous nature of melt-spun samples was confirmed by X-ray diffractometry and Mössbauer spectroscopy. The X-ray diffraction patterns revealed a distinct amorphous halo. The low-field components of magnetic hyperfine field distributions on iron nuclei are observed in the Mössbauer spectra, with average hyperfine field values of 19.9 and 15.7 T for x = 0 and x = 7, respectively. Coercivity studied by vibrating sample magnetometer was about 12 A/m for x = 0 and 82 A/m for x = 7 at 300 K and about 600 A/m for x = 0 and 1200 A/m for x = 7 at 400 K. Remanence also changed with temperature, amounting to 0.64 T for x = 0 and 0.36 T for x = 7 at 300 K, while at 400 K it was 0.43 and 0.11 T for x = 0 and x = 7, respectively. It is shown that La addition has beneficial effect of shifting the Curie point towards lower temperatures together with the increase of magnitude of magnetization.
17
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Pressure Effect on Yb-Based Strongly Correlated Electron Systems

64%
Mito T., Otani M., Nakamura M., Koyama T., Wada S., Kotegawa H., Kobayashi T., Idzikowski B., Reiffers M., Sarrao J.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
47-52
EN
We studied pressure effects on YbCu_5 and YbInCu_4, good examples of the Yb-based compounds to investigate the nonmagnetic-magnetic transition in Yb-based strongly correlated electron systems. With increasing pressure, the low-temperature Fermi liquid state of YbCu_5 is gradually suppressed, suggesting the second-order like nonmagnetic-magnetic transition around the pressure of 5-6 GPa. On the other hand, in YbInCu_4 which has a pressure-induced magnetic ordered ground state above P_C=2.45 GPa, both high-temperature paramagnetic and low-temperature intermediate valence phases are insensitive to pressure. Our results confirm the first-order nature of the transition between the intermediate valence and magnetic ordered phases with pressure.
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