Ferromagnetic resonance

Searched over 200M research papers for "ferromagnetic resonance"

Research Analysis by Consensus

Consensus Meter

Yes

Possibly

Ferromagnetic Resonance: Techniques and Applications

Introduction to Ferromagnetic Resonance

Ferromagnetic resonance (FMR) is a powerful technique used to study the magnetic properties of ferromagnetic materials. It involves the resonance absorption of microwave radiation by the magnetic moments in a material when subjected to an external magnetic field. This technique provides insights into various magnetic parameters such as anisotropy, damping, and spin dynamics.

Spin-Orbit-Driven Ferromagnetic Resonance

Recent advancements have introduced a form of FMR driven by spin-orbit coupling. This method utilizes an oscillating electric current at microwave frequencies to create an effective magnetic field within the material. This approach allows for the characterization of individual nanoscale samples with uniform magnetization profiles, leveraging the non-collinearity of electron spins due to spin-orbit coupling and structural inversion asymmetry. This technique has been successfully applied to lithographically patterned (Ga,Mn)As and (Ga,Mn)(As,P) nanoscale bars, providing detailed measurements of resonant damping and anisotropy.

Electrically Detected Ferromagnetic Resonance

Electrically detected ferromagnetic resonance (EDFMR) is another innovative technique that measures changes in magnetoresistance properties under microwave irradiation. This method has been applied to thin ferromagnetic CrO2 and Fe3O4 films, where changes in sheet resistance and Hall voltage are observed during FMR. The EDFMR signals closely match conventional FMR in both resonance fields and line shapes, and the observed changes can be attributed to Joule heating effects. EDFMR is particularly useful for investigating magnetic anisotropy and magnetoresistive phenomena in micro- and nanostructures .

Ferromagnetic Resonance in Ferrites and Periodic Particle Arrays

FMR studies have also been conducted on polycrystalline ferrite systems and periodic particle arrays. In ferrites, FMR measurements at various frequencies provide insights into the magnetic properties of these materials. For periodic particle arrays, FMR spectra reveal additional resonance peaks that depend on the orientation of the external magnetic field and interparticle interactions. These peaks are associated with coupled exchange and dipolar spin-wave modes, as demonstrated through time-dependent micromagnetic simulations.

Ferromagnetic Resonance in Microwires and Nanowires

The study of FMR in single thin conducting ferromagnetic wires has shown that various resonance modes can be excited depending on the wire radius, microwave magnetic field symmetry, and skin depth. As the wire radius decreases below the nonmagnetic skin depth, a weak resonance peak separates from the main resonance, moving to a field that fulfills the Kittel’s resonance condition for an axially magnetized cylinder. This "insulator" resonance mode is predicted to dominate in nanowires, supported by experimental results on thin amorphous microwires.

Electric-Field-Induced Ferromagnetic Resonance

Electric-field-induced FMR offers a means to control spin dynamics in spintronic devices with reduced power consumption. This technique demonstrates the potential for coherent manipulation of spin excitations using electric fields alone, which could significantly enhance the efficiency of spintronic devices.

Spin-Transfer-Driven Ferromagnetic Resonance

Spin-transfer-driven FMR enables the measurement of normal modes for magnetic excitations in individual nanoscale ferromagnets. This technique provides detailed information about exchange, damping, and spin-transfer torques, which are crucial for understanding the dynamics in magnetic nanostructures. It allows for the study of resonance frequencies, amplitudes, linewidths, and line shapes as a function of microwave power, dc current, and magnetic field.

Conclusion

Ferromagnetic resonance remains a versatile and essential tool for characterizing the magnetic properties of various materials. Advances in techniques such as spin-orbit-driven FMR, EDFMR, and electric-field-induced FMR have expanded the capabilities of this method, enabling detailed studies of nanoscale samples and spintronic devices. These developments continue to enhance our understanding of magnetic phenomena and drive innovations in material science and technology.