Enhanced stability and decreased size limit for magnetic vortex state in thin permalloy nanodisk by radial modulation of thickness

IF 2.7 4区材料科学 Q3 MATERIALS SCIENCE, MULTIDISCIPLINARY Journal of Materials Research Pub Date : 2024-09-06 DOI:10.1557/s43578-024-01431-4

Akhila Priya Kotti, Amaresh Chandra Mishra

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Abstract

Magnetization reversal in thin cylindrical nanodisks with radius between 20 and 100 nm is investigated with particular emphasis to modulation of disk thickness. The nanodisk is kept 1 nm thin at the center, whereas it gradually thickens to 21 nm at the periphery. The thickness modulation stabilizes the vortex closure state as the ground state in nanodisk for radius as low as 20 nm. An onion state appears at remanence during in-plane magnetization reversal. Nudged elastic band method verifies that the vortex state is highly stable in all the nanodisks. In the nanodisk of 100 nm radius, the vortex state requires an energy of 2677 kT to transit into onion state where kT is thermal energy at room temperature. This stability however reduces with size of nanodisk and the smallest nanodisk of 20 nm radius has to surpass an energy barrier of 120 kT to topple over to onion state.

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通过径向调节厚度增强薄超耐热合金纳米盘中磁涡旋态的稳定性并降低其尺寸限制

摘要研究了半径介于 20 纳米和 100 纳米之间的薄圆柱形纳米盘中的磁化反转，特别强调了盘厚度的调节。纳米盘在中心保持 1 nm 的厚度，而在外围则逐渐增厚到 21 nm。在半径低至 20 纳米的纳米盘中，厚度调制使涡旋闭合态稳定为基态。在平面内磁化反转时，洋葱态出现在剩磁处。裸弹带法验证了涡旋态在所有纳米盘中都是高度稳定的。在半径为 100 nm 的纳米盘中，涡旋态需要 2677 kT 的能量才能过渡到洋葱态，其中 kT 是室温下的热能。然而，这种稳定性随着纳米盘尺寸的增大而减弱，最小的半径为 20 纳米的纳米盘必须超过 120 kT 的能量障碍才能进入洋葱态。

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来源期刊

Journal of Materials Research 工程技术-材料科学：综合

CiteScore

4.50

自引率

3.70%

发文量

362

审稿时长

2.8 months

期刊介绍： Journal of Materials Research (JMR) publishes the latest advances about the creation of new materials and materials with novel functionalities, fundamental understanding of processes that control the response of materials, and development of materials with significant performance improvements relative to state of the art materials. JMR welcomes papers that highlight novel processing techniques, the application and development of new analytical tools, and interpretation of fundamental materials science to achieve enhanced materials properties and uses. Materials research papers in the following topical areas are welcome. • Novel materials discovery • Electronic, photonic and magnetic materials • Energy Conversion and storage materials • New thermal and structural materials • Soft materials • Biomaterials and related topics • Nanoscale science and technology • Advances in materials characterization methods and techniques • Computational materials science, modeling and theory