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1

Stark and Zeeman Effects in Nd_{2}Fe_{14}B and Pr_{2}Fe_{14}B Intermetallics

100%

Radwański R., Franse J.

Acta Physica Polonica A

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1996

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vol. 90

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issue 1

223-232

EN

The energy level scheme of the Nd^{3+} and Pr^{3+} ions in ferromagnetic Nd_{2}Fe_{14}B and Pr_{2}Fe_{14}B intermetallic compounds was evaluated on the basis of all known experiments. In calculations the effect of charge (Stark effect) and spin-dependent (Zeeman effect) interactions were taken into account by means of the crystal-field and molecular-field approximation, respectively. The derived energy level scheme is associated with the removal of the degeneracy of the lowest multiplet given by Hund's rules, i.e. ^{4}I_{9/2} (Nd^{3+}) and ^{3}H_{4} (Pr^{3+}). The revealed low-energy electronic structure (<25 meV = 200 cm^{-1}) is associated with many-electron states of the RE^{3+} ions. Magnetic and electronic properties resulting from this fine structure are compared with all known experimental results. The localized crystal electric field levels exist also in Nd_{2}CuO_{4}, an ionic compound which by doping with Ce becomes high-T_{c} superconductor, indicating the formation of crystal electric field states independently on the metallic or ionic state.

2

Importance of the Spin-Orbit Coupling for 3d-Ion Compounds: the Case of NiO

100%

Radwański R., Ropka Z.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

963-965

EN

The orbital and spin moment of the Ni^{2+} ion in NiO has been calculated at 0 K to be 0.54 μ_{B} and 1.99 μ_{B} respectively. Such large orbital moment, more than 20% of the total moment of 2.53 μ_{B}, proves the need for the "unquenching" of the orbital moment in compounds containing 3d ions. It turns out that the spin-orbit coupling is indispensable for description of magnetic and electronic properties of 3d-ion compounds.

3

Crystal-Field Origin of the Giant Magnetocrystalline Anisotropy of PrRu_{2}Si_{2}

81%

Michalski R., Ropka Z., Radwański R.

Acta Physica Polonica A

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2000

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vol. 97

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issue 5

767-770

EN

PrRu_{2}Si_{2} shows ferromagnetism below 14 K with the ordered moment of 2.7μ_{B}. It exhibits an enormous magnetic anisotropy at 4.2 K with the anisotropy field of about 400 T. We have attrributed the magnetism of PrRu_{2}Si_{2} to the Pr^{3+} ions. Thus we performed calculations of the fine electronic structure of the Pr^{3+} ion in the tetragonal symmetry, relevant to PrRu_{2}Si_{2}, taking into account crystal-field and inter-site exchange interactions. Our calculations reproduce well the zero-temperature moment, the single-crystalline magnetization curves, and giant anisotropy field as 400 T. The magnetocrystalline-anisotropy energy K_{1} of 59 J/cm^{3} is the largest known anisotropy - the anisotropy energy of the Nd_{2}Fe_{14}B supermagnet amounts to 12.5 J/cm^{3} only. Unfortunately, this giant anisotropy is confined to low temperatures only which prohibits its technical applications in the permanent-magnet industry.

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3 Acta Physica Polonica A

2 2000

1 1996

3 Radwański R.

2 Ropka Z.

1 Franse J.

1 Michalski R.

Stark and Zeeman Effects in Nd_{2}Fe_{14}B and Pr_{2}Fe_{14}B Intermetallics

Importance of the Spin-Orbit Coupling for 3d-Ion Compounds: the Case of NiO

Crystal-Field Origin of the Giant Magnetocrystalline Anisotropy of PrRu_{2}Si_{2}