TY - JOUR
T1 - Annealing-induced alloy formation in Pd/Fe bilayers on Si(1 1 1) for hydrogen sensing
AU - Mudinepalli, Venkata Ramana
AU - Tsai, Cheng Jui
AU - Chuang, Ying Chin
AU - Chang, Po Chun
AU - Plusnin, N.
AU - Lin, Wen Chin
N1 - Funding Information:
This work was financially sponsored by Ministry of Science and Technology, Taiwan under Grant Nos. NSC 102-2923-M-003-002-MY3 , NSC 102-2112-M-003-003-MY3 .
Publisher Copyright:
© 2016 Elsevier B.V. All rights reserved.
PY - 2016/3/15
Y1 - 2016/3/15
N2 - The bilayers of Pd and Fe with different thickness and relative positions were grown on Si(1 1 1)-7 × 7 surface at room temperature. For the investigation of the thermal annealing induced inter-diffusion and the corresponding magnetic behavior, Auger electron spectroscopy (AES) measurement was carried out after various annealing processes, including the variation of annealing duration and temperature. With the annealing temperature of 300-500 K, the Pd/Fe bilayers were stable. Slight Si segregated into the thin film at around 700 K. Above 700 K, more serious Si segregation occurred and most of the Pd/Fe bilayer was mixed with Si, forming a silicide layer. 700-800 K annealing also induced change of Pd/Fe AES ratio, indicating the inter-diffusion between Pd and Fe layers. To overcome the unavoidable silicide formation induced magnetic dead layer, a relative thick Fe film of 20 ML capped with 1.5 ML Pd was chosen for the investigation of magnetism. The magnetic coercivity (H c ) increased by 2-3 times with the annealing temperature up to 740 K. Obvious hydrogenation effect was observed in 710 K-annealed sample; the in-plane H c increased by more than 10% when the hydrogen pressure was above 200 mbar. After further annealing at 740-800 K, the hydrogenation effect on H c became nearly unobservable. The annealing induced Pd-rich magnetic interface is supposed to dominate the hydrogenation effect on magnetism.
AB - The bilayers of Pd and Fe with different thickness and relative positions were grown on Si(1 1 1)-7 × 7 surface at room temperature. For the investigation of the thermal annealing induced inter-diffusion and the corresponding magnetic behavior, Auger electron spectroscopy (AES) measurement was carried out after various annealing processes, including the variation of annealing duration and temperature. With the annealing temperature of 300-500 K, the Pd/Fe bilayers were stable. Slight Si segregated into the thin film at around 700 K. Above 700 K, more serious Si segregation occurred and most of the Pd/Fe bilayer was mixed with Si, forming a silicide layer. 700-800 K annealing also induced change of Pd/Fe AES ratio, indicating the inter-diffusion between Pd and Fe layers. To overcome the unavoidable silicide formation induced magnetic dead layer, a relative thick Fe film of 20 ML capped with 1.5 ML Pd was chosen for the investigation of magnetism. The magnetic coercivity (H c ) increased by 2-3 times with the annealing temperature up to 740 K. Obvious hydrogenation effect was observed in 710 K-annealed sample; the in-plane H c increased by more than 10% when the hydrogen pressure was above 200 mbar. After further annealing at 740-800 K, the hydrogenation effect on H c became nearly unobservable. The annealing induced Pd-rich magnetic interface is supposed to dominate the hydrogenation effect on magnetism.
KW - Hydrogenation
KW - Surface magnetism
KW - Ultrathin film
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U2 - 10.1016/j.apsusc.2016.01.057
DO - 10.1016/j.apsusc.2016.01.057
M3 - Article
AN - SCOPUS:84960154241
SN - 0169-4332
VL - 366
SP - 38
EP - 45
JO - Applied Surface Science
JF - Applied Surface Science
ER -