TY - JOUR
T1 - Collective magnetic response of inhomogeneous nanoisland FeNi films around the percolation transition
AU - Kovaleva, Natalia N.
AU - Bagdinov, Anton V.
AU - Stupakov, Alexandr
AU - Dejneka, Alexandr
AU - Demikhov, Evgenii I.
AU - Gorbatsevich, Alexandr A.
AU - Pudonin, Fedor A.
AU - Kugel, Kliment I.
AU - Kusmartsev, Feodor V.
N1 - Funding Information:
Funding information This work was supported by the grant N17-72-20030 of the RSF (Russian Science Foundation). The experiments were performed in the Materials Growth and Measurement Laboratory MGML (see http://mgml.eu).
Publisher Copyright:
© 2018, Springer Science+Business Media B.V., part of Springer Nature.
PY - 2018/4/1
Y1 - 2018/4/1
N2 - By using superconducting quantum interference device (SQUID) magnetometry, we investigated anisotropic high-field (H ≲ 7T) low-temperature (10 K) magnetization response of inhomogeneous nanoisland FeNi films grown by rf sputtering deposition on Sitall (TiO2) glass substrates. In the grown FeNi films, the FeNi layer nominal thickness varied from 0.6 to 2.5 nm, across the percolation transition at the dc ≃ 1.8 nm. We discovered that, beyond conventional spin-magnetism of Fe21Ni79 permalloy, the extracted out-of-plane magnetization response of the nanoisland FeNi films is not saturated in the range of investigated magnetic fields and exhibits paramagnetic-like behavior. We found that the anomalous out-of-plane magnetization response exhibits an escalating slope with increase in the nominal film thickness from 0.6 to 1.1 nm, however, it decreases with further increase in the film thickness, and then practically vanishes on approaching the FeNi film percolation threshold. At the same time, the in-plane response demonstrates saturation behavior above 1.5–2T, competing with anomalously large diamagnetic-like response, which becomes pronounced at high magnetic fields. It is possible that the supported-metal interaction leads to the creation of a thin charge-transfer (CT) layer and a Schottky barrier at the FeNi film/Sitall (TiO2) interface. Then, in the system with nanoscale circular domains, the observed anomalous paramagnetic-like magnetization response can be associated with a large orbital moment of the localized electrons. In addition, the inhomogeneous nanoisland FeNi films can possess spontaneous ordering of toroidal moments, which can be either of orbital or spin origin. The system with toroidal inhomogeneity can lead to anomalously strong diamagnetic-like response. The observed magnetization response is determined by the interplay between the paramagnetic- and diamagnetic-like contributions.
AB - By using superconducting quantum interference device (SQUID) magnetometry, we investigated anisotropic high-field (H ≲ 7T) low-temperature (10 K) magnetization response of inhomogeneous nanoisland FeNi films grown by rf sputtering deposition on Sitall (TiO2) glass substrates. In the grown FeNi films, the FeNi layer nominal thickness varied from 0.6 to 2.5 nm, across the percolation transition at the dc ≃ 1.8 nm. We discovered that, beyond conventional spin-magnetism of Fe21Ni79 permalloy, the extracted out-of-plane magnetization response of the nanoisland FeNi films is not saturated in the range of investigated magnetic fields and exhibits paramagnetic-like behavior. We found that the anomalous out-of-plane magnetization response exhibits an escalating slope with increase in the nominal film thickness from 0.6 to 1.1 nm, however, it decreases with further increase in the film thickness, and then practically vanishes on approaching the FeNi film percolation threshold. At the same time, the in-plane response demonstrates saturation behavior above 1.5–2T, competing with anomalously large diamagnetic-like response, which becomes pronounced at high magnetic fields. It is possible that the supported-metal interaction leads to the creation of a thin charge-transfer (CT) layer and a Schottky barrier at the FeNi film/Sitall (TiO2) interface. Then, in the system with nanoscale circular domains, the observed anomalous paramagnetic-like magnetization response can be associated with a large orbital moment of the localized electrons. In addition, the inhomogeneous nanoisland FeNi films can possess spontaneous ordering of toroidal moments, which can be either of orbital or spin origin. The system with toroidal inhomogeneity can lead to anomalously strong diamagnetic-like response. The observed magnetization response is determined by the interplay between the paramagnetic- and diamagnetic-like contributions.
KW - Collective high-field magnetic response
KW - FeNi/TiO interface
KW - Inhomogeneous nanoscale domain arrays
KW - Nanoisland FeNi permalloy films
KW - SQUID magnetometry
UR - http://www.scopus.com/inward/record.url?scp=85045754244&partnerID=8YFLogxK
U2 - 10.1007/s11051-018-4214-6
DO - 10.1007/s11051-018-4214-6
M3 - Article
AN - SCOPUS:85045754244
SN - 1388-0764
VL - 20
JO - Journal of Nanoparticle Research
JF - Journal of Nanoparticle Research
IS - 4
M1 - 109
ER -