Magnetic force resonance microscopy Victor Mironov Institute for physics of microstructures RAS, Nizhny Novgorod, Russia “SPM 2017”, Yekaterinburg, August, 2017

Content Cantilever AFM oscillations Magnetic force microscopy (MFM) Eddy current microscopy (ECM) Magnetic resonance force microscopy (MRFM) Conclusion

Atomic force microscope FB Z Photodetector Laser 

Cantilever oscillations m k Piezo

Magnetic cantilever oscillations over the magnetic sample Eddy current microscopy ECM Magnetic force microscopy MFM Magnetic resonance force microscopy MRFM Hybrid microscopy ECM + MFM + MRFM

Magnetic force microscopy

Magnetic force microscope (MFM) FB Z Photo detector Laser  Magnetic coating Y. Martin, H. K. Wickramasinghe - Applied Physics Letters, 50, 1455 (1987).

Probe-sample magnetic interaction Magnetic layer

Probe-sample magnetic interaction

Probe-sample magnetic interaction

Magnetic force microscopy MFM images of computer disc

MFM of single domain nanoparticles 600 × 400 × 20 nm

Array of single domain nanoparticles

MFM tip induced remagnetization

MFM tip induced remagnetization

Helicoidal state in three layer stack с b (1) (2) (3) d A.A. Fraerman, B.A. Gribkov et al. - J. Appl. Phys., 103, 073916, (2008).

Spiral MFM contrast for three layer stack (b) Model MFM contrast Experimental MFM image A.A.Fraerman, B.A.Gribkov et al. - J. Appl. Phys., 103, 073916, (2008).

Eddy current microscopy

Eddy currents

Cantilever oscillations Insulator Copper V. Nalladega et al., Rev. Sci. Instr., 79, 073705 (2008)

Eddy current microscopy of local conductivity ECM image 5×5 m AFM image 5×5 m B. Hoffmann et al., Appl. Phys. A, 66, S409 (1998)

ECM spatial resolution AFM ECM V. Nalladega et al., Rev. Sci. Instr., 79, 073705 (2008)

Magnetic resonance force microscopy

Magnetic resonance force microscopy Traditional MR Imaging Detector Inductor resonant slice 0.1 мм Hrf Н H Δ+ MRFM Magnetic resonance force microscopy (MRFM) is a new microscopic imaging technique that combines aspects of atomic force microscopy (AFM) with magnetic resonance imaging (MRI). Its challenging possibilities are: true three-dimensional, sub-surface imaging with potential atomic resolution and chemical specificity. MRFM signals arise when spins in a sample are modulated by an applied radio-frequency field, precisely as in conventional magnetic resonance imaging. Only spins within a thin resonant slice are affected; the spins below are in too strong a field for resonance, while spins above are in too weak a field. The ultra-high force sensitivity of the resonator demonstrated in the AFM enables much higher sensitivity to spin magnetization in MRFM and thus much higher spatial resolution than is achievable in conventional MRI. Detector Inductor Hrf 0.1 µm H Δ+ John A. Sidles, University of Washington, School of Medicine, Department of Orthopedics J. A. Sidles, Appl. Phys. Lett. 58, 2854 (1991) 24

Ferromagnetic resonance

Principles of FMR MRFM h ωmod = ωres t ωFMR= 1 GHz ω res= 50 GHz

Principles of FMR MRFM MW Generator Control system Modulator Magnet

MRFM sample pumping ~ ~ Vrf Hrf S G (а) Vrf (b) (b) Hrf (c) (c) G S

MRFM of Permalloy nanodisc (а) (b) (c) (d) (e) (f) F.Guo, et al., Phys. Rev. Lett., 110, 017601 (2013).

MRFM of single domain wall in curved nanowire (b) (c) (e) (f) (d)

Conclusion We considered the different methods of sample investigation with magnetic SPM probe based on mechanical resonance of cantilever. Magnetic force microscopy (MFM). Eddy current microscopy (ECM). Magnetic resonance force microscopy (MRFM). All these modes and their combinations can be used for complex characterization of magnetic nanostructures.

Acknowledgements Project of Russian Science Foundation   RSF № 16-12-10254   «Magnetic resonance force microscopy of ferromagnetic nanostructures» Official web site: http://mrfm.ipmras.ru/

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