Advanced magneto-optical microscopy: Imaging from picoseconds to centimeters - imaging spin waves and temperature distributions (invited)

© 2016 Author(s).Recent developments in the observation of magnetic domains and domain walls by wide-field optical microscopy based on the magneto-optical Kerr, Faraday, Voigt, and Gradient effect are reviewed. Emphasis is given to the existence of higher order magneto-optical effects for advanced magnetic imaging. Fundamental concepts and advances in methodology are discussed that allow for imaging of magnetic domains on various length and time scales. Time-resolved imaging of electric field induced domain wall rotation is shown. Visualization of magnetization dynamics down to picosecond temporal resolution for the imaging of spin-waves and magneto-optical multi-effect domain imaging techniques for obtaining vectorial information are demonstrated. Beyond conventional domain imaging, the use of a magneto-optical indicator technique for local temperature sensing is shown

Observation of the magnetic domain structures in Cu0,47_{0,47}Ni0,53_{0,53} thin films at low temperatures

We report on the first experimental visualization of domain structure in films of weakly ferromagnetic Cu$_{0,47}$Ni$_{0,53}$ alloy with different thickness at liquid helium temperatures. Improved high-resolution Bitter decoration technique was used to map the magnetic contrast on the top of the films well below the Curie temperature T$_{Curie}$ ($\sim$ 60 K). In contrast to magnetic force microscopy, this technique allowed visualization of the domain structure without its disturbance while the larger areas of the sample were probed. Maze-like domain patterns, typical for perpendicular magnetic anisotropy, were observed. The average domain width was found to be about 100 nm.Comment: 4 pages, 5 figures, will be published in JETP Let

Buffer Induced Magnetic Patterning of Ultrathin Co Layer

The possibility of magnetic anisotropy engineering of ultrathin Co films in the scale of several dozen nanometers is investigated by magnetooptical magnetometry. In Au/Co/Au sandwiches the spin reorientation transition from the out-of-plane to the in-plane configuration is observed, when Co layer thickness exceeds 1.9 nm. Molybdenum as the underlayer suppresses the Co thickness range for which the perpendicular magnetization is stable. The application of patterned buffer in the form of Au islands grown on Mo layer for ultrathin Co film gives rise to the array of spatially stable magnetic dots fabrication ca. 100 nm in lateral size with magnetization perpendicular to the film plane surrounded by the area magnetized in the sample plane

Advanced magneto-optical microscopy: Imaging from picoseconds to centimeters - imaging spin waves and temperature distributions (invited)

© 2016 Author(s).Recent developments in the observation of magnetic domains and domain walls by wide-field optical microscopy based on the magneto-optical Kerr, Faraday, Voigt, and Gradient effect are reviewed. Emphasis is given to the existence of higher order magneto-optical effects for advanced magnetic imaging. Fundamental concepts and advances in methodology are discussed that allow for imaging of magnetic domains on various length and time scales. Time-resolved imaging of electric field induced domain wall rotation is shown. Visualization of magnetization dynamics down to picosecond temporal resolution for the imaging of spin-waves and magneto-optical multi-effect domain imaging techniques for obtaining vectorial information are demonstrated. Beyond conventional domain imaging, the use of a magneto-optical indicator technique for local temperature sensing is shown

Domain Structure in (NiFe/Au/Co/Au)10 Multilayers With Perpendicular Anisotropy of Co Layers

International audienc

Electrochemical Deposition of Nanowires in Porous Alumina

Electrochemical deposition is a very efficient method for producing many types of modern materials. The method is not expensive and does not have a limit for sample size. In our work the preparation of Ni, Co and Fe nanowires is presented. The obtained nanowires had different diameter and length which were tunable by template porous material and time of deposition, respectively. The quality of the prepared wires was dependent also on deposition mode. The smallest wires of the diameter around 40 nm were prepared in porous anodic alumina oxide obtained from oxalic acid. The largest ones, around 120 nm, were produced in phosphoric acid. The length could be as large as the thickness of the oxide and reached up to about 1 μm. The morphology of wires was studied by atomic force microscopy and scanning electron microscopy. The magnetic characterization was done with usage of magnetic force microscopy and the Mössbauer spectroscopy. The wires show magnetization along their growth direction

Electrochemical Deposition of Nanowires in Porous Alumina

Electrochemical deposition is a very efficient method for producing many types of modern materials. The method is not expensive and does not have a limit for sample size. In our work the preparation of Ni, Co and Fe nanowires is presented. The obtained nanowires had different diameter and length which were tunable by template porous material and time of deposition, respectively. The quality of the prepared wires was dependent also on deposition mode. The smallest wires of the diameter around 40 nm were prepared in porous anodic alumina oxide obtained from oxalic acid. The largest ones, around 120 nm, were produced in phosphoric acid. The length could be as large as the thickness of the oxide and reached up to about 1 μm. The morphology of wires was studied by atomic force microscopy and scanning electron microscopy. The magnetic characterization was done with usage of magnetic force microscopy and the Mössbauer spectroscopy. The wires show magnetization along their growth direction

Ga

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt ultrathin film are investigated by means of the X-ray magnetic circular dichroism (XMCD) technique. A large difference in the Co orbital moment is observed between out-of-plane and in-plane directions of the film at moderate Ga+ fluences of ~1-2×1014 ions/cm2, which corresponds to the perpendicular magnetic anisotropy (PMA), while further increased fluences reduce the orbital moment difference, resulting in in-plane magnetization. In contrast, at much higher Ga+ fluences of ~5×1015 ions/cm2, at which PMA is observed again, no significant difference is found in the orbital moment of Co between out-of-plane and in-plane directions. Different origins are thus suggested for the appearance of PMA induced by the irradiation between moderate and high Ga+ fluences

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt thin film studied by X-ray magnetic circular dichroism

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt ultrathin film are investigated by means of the X-ray magnetic circular dichroism (XMCD) technique. A large difference in the Co orbital moment is observed between out-of-plane and in-plane directions of the film at moderate Ga+ fluences of ~1-2×1014 ions/cm2, which corresponds to the perpendicular magnetic anisotropy (PMA), while further increased fluences reduce the orbital moment difference, resulting in in-plane magnetization. In contrast, at much higher Ga+ fluences of ~5×1015 ions/cm2, at which PMA is observed again, no significant difference is found in the orbital moment of Co between out-of-plane and in-plane directions. Different origins are thus suggested for the appearance of PMA induced by the irradiation between moderate and high Ga+ fluences

Ga +

Ga+ ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt ultrathin film are investigated by means of the X-ray magnetic circular dichroism (XMCD) technique. A large difference in the Co orbital moment is observed between out-of-plane and in-plane directions of the film at moderate Ga+ fluences of ~1-2×1014 ions/cm2, which corresponds to the perpendicular magnetic anisotropy (PMA), while further increased fluences reduce the orbital moment difference, resulting in in-plane magnetization. In contrast, at much higher Ga+ fluences of ~5×1015 ions/cm2, at which PMA is observed again, no significant difference is found in the orbital moment of Co between out-of-plane and in-plane directions. Different origins are thus suggested for the appearance of PMA induced by the irradiation between moderate and high Ga+ fluences