Epitaxial Ni–Mn–Ga thin films have promising application potential in micro-electro-mechanical sensing and actuation systems. To date, large abrupt magnetization changes have been observed in some epitaxial Ni–Mn–...Epitaxial Ni–Mn–Ga thin films have promising application potential in micro-electro-mechanical sensing and actuation systems. To date, large abrupt magnetization changes have been observed in some epitaxial Ni–Mn–Ga thin films, but their origin-either from magnetically induced martensite variant reorientation(MIR) or magnetic domain evolution-has been discussed controversially. In the present work, we investigated the evolutions of the magnetic domain and microstructure of a typical epitaxial Ni–Mn–Ga thin film through wide-field magneto-optical Kerr-microscopy. It is demonstrated that the abrupt magnetization changes in the hysteresis loops should be attributed to the magnetic domain evolution instead of the MIR.展开更多
Cylindrical ferromagnetic tubes are notable for their geometry-driven physical phenomena,making them promising for future technological applications.Self-assembly rolling technology is used to create tubes with high s...Cylindrical ferromagnetic tubes are notable for their geometry-driven physical phenomena,making them promising for future technological applications.Self-assembly rolling technology is used to create tubes with high surface quality and side edges,which are crucial for customizing magnetic anisotropy through magnetostatic interactions at the edges.This study investigates the anisotropy induced by these interactions in magnetostriction-free permalloy membranes.Thin planar membranes of varying dimensions were transformed into tubular structures with curvature radii in the tens of microns and winding numbers from 0.6 to 1.5.Experimental results reveal that magnetostatic energy is minimized when the winding number exceeds 0.8-0.9 by adopting an azimuthal domain pattern,or flux-closure configuration,from previously axial domains.Theseresults are supported by analytical calculations of the equilibrium magnetic state of both planar and curved membranes,considering shape anisotropy constants.These constants were derived from magnetostatic energy calculations assuming a single domain configuration and applied to various geometries and curvatures.This research advances the understanding of anisotropy tuning in curved thin-film architectures,focusing on achieving azimuthal magnetic anisotropy in soft ferromagnetic tubular structures without additional induced anisotropy,a key step for applications in data storage,field sensors,and biomedicine relying on 3D magnetic structures.展开更多
The extension of 2D ferromagnetic structures into 3D curved geometry enables to tune its magnetic properties such as uniaxial magnetic anisotropy.Tuning the anisotropy with strain and curvature has become a promising ...The extension of 2D ferromagnetic structures into 3D curved geometry enables to tune its magnetic properties such as uniaxial magnetic anisotropy.Tuning the anisotropy with strain and curvature has become a promising ingredient in modern electronics,such as flexible and stretchable magnetoelectronic devices,impedance-based field sensors,and strain gauges,however,has been limited to extended thin films and to only moderate bending.By applying a self-assembly rolling technique using a polymeric platform,we provide a template that allows homogeneous and controlled bending of a functional layer adhered to it,irrespective of its shape and size.This is an intriguing possibility to tailor the sign and magnitude of the surface strain of integrated,micronsized devices.In this article,the impact of strain and curvature on the magnetic ground state and anisotropy is quantified for thinfilm Permalloy micro-scale structures,fabricated on the surface of the tubular architectures,using solely electrical measurements.展开更多
基金supported by the National Natural Science Foundation of China (Grants Nos. 52071071)the Liaoning Revitalization Talents Program (Grant No. XLYC1802023)+1 种基金the Fundamental Research Funds for the Central Universities of China (Grant Nos. N2102006)the Program of Introducing Talents of Discipline Innovation to Universities 2.0 (the 111 Project of China 2.0, No. BP0719037)。
文摘Epitaxial Ni–Mn–Ga thin films have promising application potential in micro-electro-mechanical sensing and actuation systems. To date, large abrupt magnetization changes have been observed in some epitaxial Ni–Mn–Ga thin films, but their origin-either from magnetically induced martensite variant reorientation(MIR) or magnetic domain evolution-has been discussed controversially. In the present work, we investigated the evolutions of the magnetic domain and microstructure of a typical epitaxial Ni–Mn–Ga thin film through wide-field magneto-optical Kerr-microscopy. It is demonstrated that the abrupt magnetization changes in the hysteresis loops should be attributed to the magnetic domain evolution instead of the MIR.
基金supported by the Fondecyt Iniciacion Grant No.11190184the European Community under the Horizon 2020 Program,Contract No.101001290(3DNANOMAG)。
文摘Cylindrical ferromagnetic tubes are notable for their geometry-driven physical phenomena,making them promising for future technological applications.Self-assembly rolling technology is used to create tubes with high surface quality and side edges,which are crucial for customizing magnetic anisotropy through magnetostatic interactions at the edges.This study investigates the anisotropy induced by these interactions in magnetostriction-free permalloy membranes.Thin planar membranes of varying dimensions were transformed into tubular structures with curvature radii in the tens of microns and winding numbers from 0.6 to 1.5.Experimental results reveal that magnetostatic energy is minimized when the winding number exceeds 0.8-0.9 by adopting an azimuthal domain pattern,or flux-closure configuration,from previously axial domains.Theseresults are supported by analytical calculations of the equilibrium magnetic state of both planar and curved membranes,considering shape anisotropy constants.These constants were derived from magnetostatic energy calculations assuming a single domain configuration and applied to various geometries and curvatures.This research advances the understanding of anisotropy tuning in curved thin-film architectures,focusing on achieving azimuthal magnetic anisotropy in soft ferromagnetic tubular structures without additional induced anisotropy,a key step for applications in data storage,field sensors,and biomedicine relying on 3D magnetic structures.
基金funding by Fondecyt Iniciacion Grant No.11190184funding from the German Research Foundation DFG (Gottfried Wilhelm Leibniz Prize granted in 2018,SCHM 1298/22-1 and KA5051/1-1 and KA5051/3-1)the Leibniz Association (Leibniz Transfer Program T62/2019).
文摘The extension of 2D ferromagnetic structures into 3D curved geometry enables to tune its magnetic properties such as uniaxial magnetic anisotropy.Tuning the anisotropy with strain and curvature has become a promising ingredient in modern electronics,such as flexible and stretchable magnetoelectronic devices,impedance-based field sensors,and strain gauges,however,has been limited to extended thin films and to only moderate bending.By applying a self-assembly rolling technique using a polymeric platform,we provide a template that allows homogeneous and controlled bending of a functional layer adhered to it,irrespective of its shape and size.This is an intriguing possibility to tailor the sign and magnitude of the surface strain of integrated,micronsized devices.In this article,the impact of strain and curvature on the magnetic ground state and anisotropy is quantified for thinfilm Permalloy micro-scale structures,fabricated on the surface of the tubular architectures,using solely electrical measurements.
