Linear chains of nanomagnets: engineering the effective magnetic anisotropy

We have investigated the exchange bias in CVD grown epitaxial CrO2/Cr2O3 bilayer thin films using hysteresis loops and resonant RF transverse susceptibility. M-H loops indicated an enhanced coercivity without appreciable loop shift and the transverse susceptibility in CrO2/Cr2O3 bilayers revealed features associated with both the ferromagnetic and antiferromagnetic phases. In addition, TS yielded large anisotropy constant (Keff) values depending on the fraction of Cr2O3 present. The large anisotropy fields observed cannot be accounted for by the variable thickness of CrO2 alone and are indicative of possible exchange coupling between CrO2 and Cr2O3 phases that significantly affects the effective magnetic anisotropy.

Download Full-text

Temperature Dependence of the Effective Magnetic Anisotropy Field and Ferromagnetic Resonance Linewidth in Polycrystalline Complex Substituted Magnetically Uniaxial Hexagonal Ferrites in the Frequency Range of 25–67 GHz

Technical Physics ◽

10.1134/s1063784220050230 ◽

2020 ◽

Vol 65 (5) ◽

pp. 749-753

Author(s):

S. V. Shcherbakov ◽

A. G. Nalogin ◽

V. G. Kostishin ◽

A. S. Semenov ◽

N. E. Adiatulina ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Temperature Dependence ◽

Ferromagnetic Resonance ◽

Anisotropy Field ◽

Hexagonal Ferrites ◽

Frequency Range ◽

Resonance Linewidth ◽

Effective Magnetic Anisotropy ◽

Ferromagnetic Resonance Linewidth

Download Full-text

Measurement of effective magnetic anisotropy field and ferromagnetic resonance bandwidth at ferromagnetic resonance frequency in magnetically uniaxial hexagonal ferrites

Modern Electronic Materials ◽

10.3897/j.moem.5.1.51295 ◽

2019 ◽

Vol 5 (1) ◽

pp. 33-39

Author(s):

Alexey S. Semenov ◽

Aleksey G. Nalogin ◽

Sergey V. Shcherbakov ◽

Alexander V. Myasnikov ◽

Igor M. Isaev ◽

...

Keyword(s):

Magnetic Anisotropy ◽

Ferromagnetic Resonance ◽

Transmission Lines ◽

Anisotropy Field ◽

Nominal Composition ◽

Hexagonal Ferrites ◽

Magnetic Texture ◽

Measurement Results ◽

Effective Magnetic Anisotropy ◽

Ferromagnetic Resonance Frequency

In this work we have considered metrological problems and measurement of magnetic parameters and presented methods of measuring effective magnetic anisotropy field HAeff and ferromagnetic resonance bandwidth ∆H in magnetically uniaxial hexagonal ferrites in the electromagnetic microwave working frequency range. The methods allow measuring HAeff in the 10–23 and 28–40 kE ranges and ∆H in the 0.5–5.0 range. One method (suitable for wavelength measurements in free space in the 3-mm wavelength range) has been implemented for the 78.33–118.1 GHz range. The other method (based on the use of microstrip transmission lines) has been implemented for the 25–67 GHz range. The methods have been tested for polycrystalline specimens of hexagonal barium and strontium ferrites with nominal composition or complex substituted and having high magnetic texture. The measurement results have been compared with those obtained using conventional measurement methods and spherical specimens. Our methods prove to be highly accurate and reliable.

Download Full-text

Magnetic interaction and anisotropy axes arrangement in nanoparticle aggregates can enhance or reduce the effective magnetic anisotropy

Journal of Magnetism and Magnetic Materials ◽

10.1016/j.jmmm.2019.166170 ◽

2020 ◽

Vol 498 ◽

pp. 166170

Author(s):

V.R.R. Aquino ◽

L.C. Figueiredo ◽

J.A.H. Coaquira ◽

M.H. Sousa ◽

A.F. Bakuzis

Keyword(s):

Magnetic Anisotropy ◽

Magnetic Interaction ◽

Effective Magnetic Anisotropy ◽

Nanoparticle Aggregates

Download Full-text

Effects of Si content on effective magnetic anisotropy in Fe/sub 87-x/Cu/sub 1/Nb/sub 3/Si/sub x/B/sub 9/ nanocrystalline alloys

IEEE Transactions on Magnetics ◽

10.1109/20.492895 ◽

1996 ◽

Vol 32 (3) ◽

pp. 1967-1969

Author(s):

Xiang-Yuan Xiong ◽

Kai-Yuan Ho ◽

Zhe Ji

Keyword(s):

Magnetic Anisotropy ◽

Nanocrystalline Alloys ◽

Effective Magnetic Anisotropy ◽

Si Content

Download Full-text

Magnetism of Ultrathin Fe Films in the Vicinity of Transition from Ferromagnetism to Superparamagnetism

Materials Science Forum ◽

10.4028/www.scientific.net/msf.512.165 ◽

2006 ◽

Vol 512 ◽

pp. 165-170

Author(s):

Yu Shiratsuchi ◽

Yasushi Endo ◽

Masahiko Yamamoto

Keyword(s):

Magnetic Anisotropy ◽

Growth Temperature ◽

Magnetic State ◽

Ferromagnetic State ◽

Film Structure ◽

Dominant Factor ◽

Magnetic Anisotropy Energy ◽

Flat Substrate ◽

Effective Magnetic Anisotropy ◽

Superparamagnetic State

We have investigated the magnetism of ultrathin Fe films grown on the inclined Al2O3(0001), especially, in the vicinity of ferromagnetic-superparamagnetic transition. In the transition region, the magnetic state of Fe films is the coexistence of ferromagnetism and superparamagnetism. The ratio of the components in ferromagnetic and superparamagnetic state is dependent on the growth temperature. For Fe grown on the flat substrate without the inclination, as the growth temperature increases, the ratio of the component in ferromagnetic state increases, reaches to the maximum and decreases again. On the presence of substrate inclination, the ratio of the component in ferromagnetic state increases, reaches to the maximum and decreases again. decreases monotonically with increasing growth temperature. We investigated the dominant factor of the complex magnetic state, and clarified that the complex magnetic state is dominated by the change of the film structure and the effective magnetic anisotropy energy.

Download Full-text