Magnetometry of Individual Polycrystalline Ferromagnetic Nanowires

Abstract

Ferromagnetic nanowires are finding use as untethered sensors and actuators for probing micro-and nanoscale biophysical phenomena, such as for localized sensing and application of forces and torques on biological samples, for tissue heating through magnetic hyperthermia, and for micro-rheology. Quantifying the magnetic properties of individual isolated nanowires is crucial for such applications. We use dynamic cantilever magnetometry to measure the magnetic properties of individual sub-500nm diameter polycrystalline nanowires of Ni and Ni 80 Co 20 fabricated by template-assisted electrochemical deposition. The values are compared with bulk, ensemble measurements when the nanowires are still embedded within their growth matrix. We find that single-particle and ensemble measurements of nanowires yield significantly different results that reflect inter-nanowire interactions and chemical modifications of the sample during the release process from the growth matrix. The results highlight the importance of performing single-particle characterization for objects that will be used as individual magnetic nanoactuators or nanosensors in biomedical applications.2

Direct observation of transverse and vortex metastable magnetic domains in cylindrical nanowires

“…Cylindrical magnetic nanowires (NWs) as single nanostructures or as part of three-dimensional ordered architectures are considered for applications in nanotechnology areas, such as magnetic recording, microwave devices, functionalization for biomagnetics, and, more recently, for thermomagnetoelectric devices [1][2][3]. They are proposed in spintronics as alternatives to planar nanostrips owing to their specific advantages, such as the possibility to tailor the type of domain wall (DW) by adjusting the geometry [4], DW stability during motion [5], and the suppression of the Walker breakdown [6,7].…”

Theory of quantum acoustomagnonics and acoustomechanics with a micromagnet

“…Let us derive the coupling between the center-of-mass motion of the micromagnet and its magnonic modes. We assume that the micromagnet is trapped in a threedimensional harmonic potential with frequencies ω tx , ω ty , and ω tz , either by levitation [45,47,48,51] or by weak clamping to a high-Q micromechanical oscillator [7,[38][39][40][41][42] (see Fig. 5b).…”

“…This versatility enables a variety of applications, ranging from fundamental physics [33,34] to quantum technologies [12,14,15,30,31,[35][36][37] or microwave-to-optical conversion [12,14,24,36]. A particularly promising prospect is to largely isolate single micromagnets from their environment, either by clamping them to high-Q microresonators [7,[38][39][40][41][42] or by levitating them, as theoretically studied [1,[43][44][45][46][47] and experimentally implemented [41,[48][49][50][51]. The large degree of isolation allows to explore rich internal mesoscopic quantum physics, such as the strong interaction between magnons and acoustic phonons inside the magnet, and the interplay between the internal and the external degrees of freedom, that is the center-of-mass motion and the rotation of the micromagnet.…”

Magnetic Vortex Domain Wall Observation on Polycrystalline Imperfect Iron−Cobalt Alloy Nanowires Growing on 1050 Aluminum

“…[10] Additional applications involve the design of new nanofabrication [11] and assembly [12] methods for understanding the magnetoresistance, [13] magnetoreactance, [14] and magnetization of individual Nws. [15]…”