Structure and Magnetic Properties of Layered Nanowires of 3 d -Metals, Fabricated by the Matrix Synthesis Method
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Structure and Magnetic Properties of Layered Nanowires of 3d-Metals, Fabricated by the Matrix Synthesis Method D. A. Cherkasova, D. L. Zagorskiia, *, R. I. Khaibullinb, A. E. Muslimova, and I. M. Doludenkoa a Shubnikov
Institute of Crystallography, Federal Scientific Research Center Crystallography and Photonics, Russian Academy of Sciences, Moscow, 117333 Russia b Zavoisky Physico-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences, Kazan, 420029 Russia * e-mail: [email protected] Received March 26, 2020; revised March 26, 2020; accepted April 2, 2020
Abstract—Based on PET track etched membranes, arrays of layer nanowires 100 nm in diameter, consisting of alternating Ni/Cu and Co/Cu layers are grown by the matrix synthesis method. Galvanic deposition processes are studied and conditions for fabricating layer nanowires with different thicknesses for magnetic (Ni or Co) and nonmagnetic (Cu) layer components are determined. An electron microscopic study is performed to verify conditions for fabricating layer nanowires and to correct geometrical sizes of alternating layers. Magnetization curves of produced arrays of layer nanowires are measured by vibration magnetometry methods at room temperature for two extreme orientations of a scanning magnetic field, i.e., parallel and perpendicular ones with respect to the nanowire growth axis. It is shown that the magnetic anisotropy of the nanowire array is controlled not only by the chemical composition, but also the thickness and alternation period of magnetic metal layers in nanowires. The dependence of the magnetostatic energy and demagnetizing field in the synthesized layer nanowires on the magnetic metal filling factor is numerically evaluated; the results are in qualitative agreement with experimental observations. Keywords: nanowires, electrodeposition, magnetism, matrix synthesis DOI: 10.1134/S1063783420090048
1. INTRODUCTION Quasi-one-dimensional nanostructures, i.e., nanowires (NW), nanofilaments, or nanorods are prominent and most interesting physical objects of the nanoworld. One of the methods for producing such nanostructures is matrix (template) synthesis. In this paper, we consider one of the most widely accepted versions: a polymeric porous membrane is taken as a matrix (template), whose pores are then filled with metals by electrochemical deposition. All these processes are well studied, their conditions and parameters are varied in a wide range, and the processes themselves are controlled and reproduced with high accuracy. Therefore, the matrix synthesis makes it possible to fabricate nanowire arrays of diverse types. The fabrication of NW arrays was perfected as early as in the 1990s [1]. In time, the variety of obtained NWs continuously increased, from homogeneous NWs consisting of a single metal or an alloy of various metals, to heterogeneous NWs containing alternating layers of different metals (so-called layer NWs). Currently, “gradient” NWs are also synthesized, in which the element and/or phase composition smoothly va
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