Antiferromagnetic Resonance

antiferromagnetic resonance

[¦an·tē‚fer·ō‚mag′ned·ik ′rez·ə·nəns]
(electromagnetism)
Magnetic resonance in antiferromagnetic materials which may be observed by rotating magnetic fields in either of two opposite directions.

Antiferromagnetic Resonance

 

a kind of electron magnetic resonance. Antiferromagnetic resonance manifests itself as a sharp rise in the absorption of electromagnetic energy passing through antiferromagnetic material for certain (resonant) values of the frequency v and of the intensity of the applied magnetic field H. Antiferromagnetic materials typically have an ordered arrangement of magnetic moments for the atoms (ions). Elementary magnetic moments having the same orientation in antiferromagnetic materials form so-called sublattices (two in the simplest case). In antiferromagnetic resonance resonant vibrations are excited in the magnetization vectors of the sublattices with respect both to one another and to the direction of the applied field H. The form of the dependence of v on the effective magnetic fields in antiferromagnetic materials is very complicated and varies for different crystal structures. As a rule, a single value of an applied field corresponds to two antiferromagnetic resonance frequencies. Antiferromagnetic resonance frequencies lie in the range of 10 to 1000 gigahertz.

A study of antiferromagnetic resonance permits the values of the effective magnetic fields to be determined in an antiferromagnetic material.

A. S. BOROVIK-ROMANOV

References in periodicals archive ?
Two of these modes are known well from the classical theory of antiferromagnetic resonance in the zero external magnetic field [19, 20].
Analysis of equations like (11) in physically meaningful limiting cases of small anisotropy energy as compared to the exchange energy (k [much less than] 1) and small deviations of the vectors [M.sub.1] and [M.sub.2] from the easy axis allows one to describe the antiferromagnetic resonance [19, 20] and ferromagnetic resonance [24] on a phenomenological level.
The modes given by (15a) correspond to the classical theory of antiferromagnetic resonance in zero magnetic field at the frequency [19, 20]
Since the middle of the 20th century, modes 3 and 4 have fallen beyond the focus of interest of researchers primarily because of the approximation of small deviations of the vectors [M.sub.1] and [M.sub.2] from the easy axis used in the theory of antiferromagnetic resonance and because these "ferromagnetic" modes lie much higher in energy than antiferromagnetic modes 1 and 2 (Figure 2).
Our open-end coaxial probe measurements at the end of the paper attempt to observe the weak ferromagnetic resonance due to spin canting seen particularly in antiferromagnetic resonance investigations on crystalline [alpha]-[Fe.sub.2][O.sub.3], also known as the mineral hematite (6), (8).