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Title: Magnetic vortex nucleation/annihilation in artificial-ferrimagnet microdisks

The topological nature of magnetic-vortex state gives rise to peculiar magnetization reversal observed in magnetic microdisks. Interestingly, magnetostatic and exchange energies which drive this reversal can be effectively controlled in artificial ferrimagnet heterostructures composed of rare-earth and transition metals. [Py(t)/Gd(t)] 25 (t=1 or 2 nm) superlattices demonstrate a pronounced change of the magnetization and exchange stiffness in a 10–300 K temperature range as well as very small magnetic anisotropy. Due to these properties, the magnetization of cylindrical microdisks composed of these artificial ferrimagnets can be transformed from the vortex to uniformly-magnetized states in a permanent magnetic field by changing the temperature. We explored the behavior of magnetization in 1.5-µm [Py(t)/Gd(t)] 25 (t=1 or 2 nm) disks at different temperatures and magnetic fields and observed that due to the energy barrier separating vortex and uniformly-magnetized states, the vortex nucleation and annihilation occur at different temperatures. This causes the temperature dependences of the Py/Gd disks magnetization to demonstrate unique hysteretic behavior in a narrow temperature range. It was discovered that for the [Py(2 nm)/Gd(2 nm)] 25 microdisks the vortex can be metastable at a certain temperature range.
Authors:
 [1] ; ORCiD logo [2] ; ORCiD logo [2] ;  [2] ;  [2] ; ORCiD logo [2] ;  [2]
  1. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Div.; Texas A & M Univ., College Station, TX (United States). Dept. of Physics and Astronomy
  2. Argonne National Lab. (ANL), Argonne, IL (United States). Materials Science Div.
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 122; Journal Issue: 8; Journal ID: ISSN 0021-8979
Publisher:
American Institute of Physics (AIP)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
OSTI Identifier:
1393542
Alternate Identifier(s):
OSTI ID: 1376738

Lapa, Pavel N., Ding, Junjia, Phatak, Charudatta, Pearson, John E., Jiang, J. S., Hoffmann, Axel, and Novosad, Valentine. Magnetic vortex nucleation/annihilation in artificial-ferrimagnet microdisks. United States: N. p., Web. doi:10.1063/1.4999089.
Lapa, Pavel N., Ding, Junjia, Phatak, Charudatta, Pearson, John E., Jiang, J. S., Hoffmann, Axel, & Novosad, Valentine. Magnetic vortex nucleation/annihilation in artificial-ferrimagnet microdisks. United States. doi:10.1063/1.4999089.
Lapa, Pavel N., Ding, Junjia, Phatak, Charudatta, Pearson, John E., Jiang, J. S., Hoffmann, Axel, and Novosad, Valentine. 2017. "Magnetic vortex nucleation/annihilation in artificial-ferrimagnet microdisks". United States. doi:10.1063/1.4999089. https://www.osti.gov/servlets/purl/1393542.
@article{osti_1393542,
title = {Magnetic vortex nucleation/annihilation in artificial-ferrimagnet microdisks},
author = {Lapa, Pavel N. and Ding, Junjia and Phatak, Charudatta and Pearson, John E. and Jiang, J. S. and Hoffmann, Axel and Novosad, Valentine},
abstractNote = {The topological nature of magnetic-vortex state gives rise to peculiar magnetization reversal observed in magnetic microdisks. Interestingly, magnetostatic and exchange energies which drive this reversal can be effectively controlled in artificial ferrimagnet heterostructures composed of rare-earth and transition metals. [Py(t)/Gd(t)]25 (t=1 or 2 nm) superlattices demonstrate a pronounced change of the magnetization and exchange stiffness in a 10–300 K temperature range as well as very small magnetic anisotropy. Due to these properties, the magnetization of cylindrical microdisks composed of these artificial ferrimagnets can be transformed from the vortex to uniformly-magnetized states in a permanent magnetic field by changing the temperature. We explored the behavior of magnetization in 1.5-µm [Py(t)/Gd(t)]25 (t=1 or 2 nm) disks at different temperatures and magnetic fields and observed that due to the energy barrier separating vortex and uniformly-magnetized states, the vortex nucleation and annihilation occur at different temperatures. This causes the temperature dependences of the Py/Gd disks magnetization to demonstrate unique hysteretic behavior in a narrow temperature range. It was discovered that for the [Py(2 nm)/Gd(2 nm)]25 microdisks the vortex can be metastable at a certain temperature range.},
doi = {10.1063/1.4999089},
journal = {Journal of Applied Physics},
number = 8,
volume = 122,
place = {United States},
year = {2017},
month = {8}
}