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Watcharee Rattanasakulthong. Magnetoresistance of mechanically alloyed Co-Cu powder. Doctoral Degree(Physics). WALAILAK UNIVERSITY. CENTER FOR LIBRARY RESOURCES AND EDUCATIONAL MEDIA. : Walailak University, 2008-07-29.
Magnetoresistance of mechanically alloyed Co-Cu powder
แมกนีโตรีซีสแตนซ์ของผงโคบอลท์-ทองแดงแบบอัลลอยด์โดยการบด
keyword:
นิเกิล - - การวิเคราะห์ - - วิจัย
ThaSH:
Walailak University
Classification :.LCCS: QC610.7
Abstract:
This research examines the magnetoresistance (MR) of Co-Cu mechanical
alloys (MAs). From elemental Co and Cu powder, the MAs were synthesized by ball
milling in ethanol. The milling time (30, 60 and 120 h) and composition (0, 10, 20,
30, 40, 50 and 100 %Co) were varied in order to obtain MAs with different properties.
Structural, thermal and magnetic properties were then characterized to establish the
relation between these properties and the MR. The composition is classified into 2
ranges according to their magnetic properties: Co-dilute MA (0, 10, 20 and 30 %Co)
and Co-concentrated MA (40, 50 and 100 %Co). The milling modifies the properties
of MAs via oxidation and cluster distribution. The milling time is divided into 3
stages: fracturing, intermediate and cold welding. The 60 h-milling, decidedly in the
intermediate state, gives rise to the narrowest cluster size distribution and hysteresis
loop. Subsequent heat treatments at 300 or 400 °C for 1 h increase oxide phases at the
expense of Co and deteriorate magnetic properties. Two types of MR were observed
in two types of bulk MAs: pressed pellets (density about 5.44 g/cm3) and capsulated
powder (density between 2.68 and 3.96 g/cm3). The pressed pellets exhibit less than
10% giant magnetoresistance (GMR) whereas the capsules show anomalous MR up to
70%. In the proposed model, the movement of magnetic clusters under the applied
magnetic field provides more efficient electrical conduction pathways and it is this
that is responsible for this new effect. This anomalous MR is dependent upon the
composition and the milling time, both of which change the cluster distribution. The
effect is also sensitive to the density of capsules which permits the movement of the
clusters such that the anomalous MR is suppressed in high density capsules and
pressed pellets. The application of this MR is limited because of its low stability, long
relaxation time and high switching field. Nevertheless, the prospects of understanding
and manipulating the electrical conduction between magnetic clusters by the magnetic
field remain intriguing.
WALAILAK UNIVERSITY. CENTER FOR LIBRARY RESOURCES AND EDUCATIONAL MEDIA
Address:
NAKON SI THAMMARAT
Email:
clm@wu.ac.th
Role:
Chairman
Created:
2008-07-29
Modified:
2008-07-29
Issued:
2008-07-29
วิทยานิพนธ์/Thesis
application/pdf
eng
DegreeName: Doctor of Philosophy (Physics)
Level: Doctoral Degree
Descipline: Physics
Grantor: Walailak University
©copyrights Walailak University
RightsAccess:
ใช้เวลา
0.040853 วินาที
Watcharee Rattanasakulthong
| Title | Contributor | Type |
|---|---|---|
| Development of GMR Sensors Based on Cobal-Ccopper Alloys.
มหาวิทยาลัยวลัยลักษณ์ Praiwan Kirdtongmee. ;Watcharee Rattanasakulthong.;Chitnarong Sirisathitkul. | บทความ/Article | |
| Magnetoresistance of mechanically alloyed Co-Cu powder
มหาวิทยาลัยวลัยลักษณ์ Watcharee Rattanasakulthong | Asst. Prof. Dr. Chatnarong Sirisathikul | วิทยานิพนธ์/Thesis |
| Effects of Annealing Temperature on Co30Cu70 Mechanical Alloys
มหาวิทยาลัยวลัยลักษณ์ Watcharee Rattanasakulthong ;Chitnarong Sirisathitkul | บทความ/Article |
Asst. Prof. Dr. Chatnarong Sirisathikul
| Title | Creator | Type and Date Create |
|---|---|---|
| Magnetoresistance of mechanically alloyed Co-Cu powder
มหาวิทยาลัยวลัยลักษณ์ Asst. Prof. Dr. Chatnarong Sirisathikul | Watcharee Rattanasakulthong | วิทยานิพนธ์/Thesis |