TY - JOUR
T1 - Large Uniaxial Anisotropy Induced in Soft Ferromagnetic Thin Films by Oblique Deposition of Underlayer
AU - Singh, Rakesh
AU - Rizzo, Nicholas D.
AU - Boochakravarthy, Ashwin
AU - Newman, Nathan
N1 - Funding Information:
The authors would like to thank R. B. Goldfarb for helpful discussions. This work was supported by Intelligence Advanced Research Projects Activity through Contract W911NF-14-C-0115. The authors acknowledge the use of facilities in the LeRoy Eyring Center for Solid State Science at Arizona State University.
Publisher Copyright:
© 2010-2012 IEEE.
PY - 2017/11/29
Y1 - 2017/11/29
N2 - We produced a large uniaxial anisotropy (Hk) in ultrathin (1.2-2.4 nm) soft ferromagnetic layers through the oblique deposition of a nanometer-thick metallic underlayer. Fe, Ni, and Ni80Fe20 (Permalloy) films deposited on a 5 nm thick Nb layer grown at an oblique angle (up to 60) exhibit an Hk 40-500 Oe and have properties that are nearly ideal for use as a fixed layer in magnetic devices, such as for magnetic memory. A much higher induced Hk is observed in Ni (500 Oe) and Fe (300 Oe) compared to Ni-Fe (40 Oe). We used this technique to increase the switching field (Hsw) by 3-5 times in an array of pattered Fe or Ni-Fe bits, and achieved an excellent relative switching distribution of about 0.05-0.06. We also controllably enhanced the Hk in the fixed layer of patterned spin-valve devices for superconducting Josephson-junction magnetic random-access memory and produced a large difference in Hsw between the fixed and free layers. Different spacer layers between the Nb and the magnetic layers either propagate (for Ru) or reduce (for Cu, Ru/Al, ion-milled Ru) the effect of the oblique Nb. This technique was also effectively used in synthetic antiferromagnet structures and, therefore, has the potential to eliminate the need for an antiferromagnetic pinning layer when it degrades magnetic device performance.
AB - We produced a large uniaxial anisotropy (Hk) in ultrathin (1.2-2.4 nm) soft ferromagnetic layers through the oblique deposition of a nanometer-thick metallic underlayer. Fe, Ni, and Ni80Fe20 (Permalloy) films deposited on a 5 nm thick Nb layer grown at an oblique angle (up to 60) exhibit an Hk 40-500 Oe and have properties that are nearly ideal for use as a fixed layer in magnetic devices, such as for magnetic memory. A much higher induced Hk is observed in Ni (500 Oe) and Fe (300 Oe) compared to Ni-Fe (40 Oe). We used this technique to increase the switching field (Hsw) by 3-5 times in an array of pattered Fe or Ni-Fe bits, and achieved an excellent relative switching distribution of about 0.05-0.06. We also controllably enhanced the Hk in the fixed layer of patterned spin-valve devices for superconducting Josephson-junction magnetic random-access memory and produced a large difference in Hsw between the fixed and free layers. Different spacer layers between the Nb and the magnetic layers either propagate (for Ru) or reduce (for Cu, Ru/Al, ion-milled Ru) the effect of the oblique Nb. This technique was also effectively used in synthetic antiferromagnet structures and, therefore, has the potential to eliminate the need for an antiferromagnetic pinning layer when it degrades magnetic device performance.
KW - Soft magnetic materials
KW - magnetic films
KW - magnetic measurements
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U2 - 10.1109/LMAG.2017.2779101
DO - 10.1109/LMAG.2017.2779101
M3 - Article
AN - SCOPUS:85037624189
SN - 1949-307X
VL - 9
JO - IEEE Magnetics Letters
JF - IEEE Magnetics Letters
M1 - 5101305
ER -