The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers
碩士 === 國立中興大學 === 材料科學與工程學系所 === 98 === Exchange bias in NiFe(9nm)/NiO(16nm) bilayers were investigated as a function of bottom NiO layers with dual ion beam bombarded by (1) different End-Hall voltage (0~150 V) for 5 minutes and (2) different periods (1~20 minutes) with VEH=150 V. And used differen...
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ndltd-TW-098NCHU51590322016-07-16T04:11:09Z http://ndltd.ncl.edu.tw/handle/46832757385754692700 The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers 離子束轟擊對鎳鐵/氧化鎳奈米雙層薄膜之結構及磁性質影響 Hsuan-Rong Huang 黃宣榕 碩士 國立中興大學 材料科學與工程學系所 98 Exchange bias in NiFe(9nm)/NiO(16nm) bilayers were investigated as a function of bottom NiO layers with dual ion beam bombarded by (1) different End-Hall voltage (0~150 V) for 5 minutes and (2) different periods (1~20 minutes) with VEH=150 V. And used different substrates (3) MgO(110) single crystal, (4) nanostripe. X-ray diffractometry results have shown NiFe/NiO bilayers consisted of a f.c.c. NiFe (a~ 3.55 Å) and a rock-salt f.c.c. NiO (a~ 4.25 Å). The grain sizes of NiO single layer range from 5 nm to 15 nm, as revealed by TEM. From AFM the more End-Hall voltage bombarded NiO surface would get smoother roughness and rised the periods cause the roughness to drop then increase. Different ion-beam energy(VEH=0V、70V、100V、130V、150V)was used to change the bottom layer of NiO structure in NiFe. Magnetometry results at 5K under a 20 kOe field-cooling, only the NiFe/NiO (VEH=150 V) bilayer deposited on a SiO2 substrate exhibited an unusual positive exchange bias field, Hex~ +200 Oe with an asymmetric hysteresis loop among all the films. The results of different periods with VEH=150 V would found exchange bias field irregularity, when tbomb.> 5 minutes all were show positive Hex. The drastic change from conventional negative to positive Hex is likely attributed to the AF NiO spin reorientation due to ion-beam bombardment, as revealed by the increased peak ratio of (200) to (111) determined by XRD. when replacing the SiO2 substrate with a MgO (110) substrate, a much smaller Hex (~ -20 Oe) was found in NiFe/NiO (VEH= 0 V and 130 V) bilayers. This indicates that the compensated AF NiO spins (thus smaller Hex) may be formed by using a MgO (110) substrate. Our results suggest that the strength and polarity of exchange bias field are affected by the substrate type (single crystal vs. amorphous) as well as by ion-beam bombardment. Discuss of NiO crystalline and surface roughness may effect exchange bias field and coervice field. The exchange bias field has different sign because influence of FM/AF interface has different exchang coupling. In other words, surface spin reorientation that is due to moderate ion-beam bombardment effects on the surface of the NiO layer. 林克偉 2010 學位論文 ; thesis 135 zh-TW |
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碩士 === 國立中興大學 === 材料科學與工程學系所 === 98 === Exchange bias in NiFe(9nm)/NiO(16nm) bilayers were investigated as a function of bottom NiO layers with dual ion beam bombarded by (1) different End-Hall voltage (0~150 V) for 5 minutes and (2) different periods (1~20 minutes) with VEH=150 V. And used different substrates (3) MgO(110) single crystal, (4) nanostripe. X-ray diffractometry results have shown NiFe/NiO bilayers consisted of a f.c.c. NiFe (a~ 3.55 Å) and a rock-salt f.c.c. NiO (a~ 4.25 Å). The grain sizes of NiO single layer range from 5 nm to 15 nm, as revealed by TEM. From AFM the more End-Hall voltage bombarded NiO surface would get smoother roughness and rised the periods cause the roughness to drop then increase.
Different ion-beam energy(VEH=0V、70V、100V、130V、150V)was used to change the bottom layer of NiO structure in NiFe. Magnetometry results at 5K under a 20 kOe field-cooling, only the NiFe/NiO (VEH=150 V) bilayer deposited on a SiO2 substrate exhibited an unusual positive exchange bias field, Hex~ +200 Oe with an asymmetric hysteresis loop among all the films.
The results of different periods with VEH=150 V would found exchange bias field irregularity, when tbomb.> 5 minutes all were show positive Hex. The drastic change from conventional negative to positive Hex is likely attributed to the AF NiO spin reorientation due to ion-beam bombardment, as revealed by the increased peak ratio of (200) to (111) determined by XRD.
when replacing the SiO2 substrate with a MgO (110) substrate, a much smaller Hex (~ -20 Oe) was found in NiFe/NiO (VEH= 0 V and 130 V) bilayers. This indicates that the compensated AF NiO spins (thus smaller Hex) may be formed by using a MgO (110) substrate. Our results suggest that the strength and polarity of exchange bias field are affected by the substrate type (single crystal vs. amorphous) as well as by ion-beam bombardment. Discuss of NiO crystalline and surface roughness may effect exchange bias field and coervice field. The exchange bias field has different sign because influence of FM/AF interface has different exchang coupling. In other words, surface spin reorientation that is due to moderate ion-beam bombardment effects on the surface of the NiO layer.
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author2 |
林克偉 |
author_facet |
林克偉 Hsuan-Rong Huang 黃宣榕 |
author |
Hsuan-Rong Huang 黃宣榕 |
spellingShingle |
Hsuan-Rong Huang 黃宣榕 The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers |
author_sort |
Hsuan-Rong Huang |
title |
The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers |
title_short |
The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers |
title_full |
The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers |
title_fullStr |
The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers |
title_full_unstemmed |
The influence of ion-beam bombardment on Structures and Magnetic Properties of NiFe/NiO Bilayers |
title_sort |
influence of ion-beam bombardment on structures and magnetic properties of nife/nio bilayers |
publishDate |
2010 |
url |
http://ndltd.ncl.edu.tw/handle/46832757385754692700 |
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