鉄/希土類金属人工格子の磁性

本文データは平成22年度国立国会図書館の学位論文(博士)のデジタル化実施により作成された画像ファイルを基にpdf変換したものである京都大学0048新制・課程博士博士(理学)甲第5514号理博第1493号新制||理||834(附属図書館)UT51-94-B158京都大学大学院理学研究科化学専攻(主査)教授 新庄 輝也, 教授 坂東 尚周, 教授 小菅 皓二学位規則第4条第1項該当Doctor of ScienceKyoto UniversityDFA

Propagation of a magnetic domain wall in magnetic wires with asymmetric notches

The propagation of a magnetic domain wall (DW) in a submicron magnetic wire consisting of a magnetic/nonmagnetic/magnetic trilayered structure with asymmetric notches was investigated by utilizing the giant magnetoresistance effect. The propagation direction of a DW was controlled by a pulsed local magnetic field, which nucleates the DW at one of the two ends of the wire. It was found that the depinning field of the DW from the notch depends on the propagation direction of the DW.Comment: 12 pages, 3 figure

Effect of Joule heating in current-driven domain wall motion

It was found that high current density needed for the current-driven domain wall motion results in the Joule heating of the sample. The sample temperature, when the current-driven domain wall motion occurred, was estimated by measuring the sample resistance during the application of a pulsed-current. The sample temperature was 750 K for the threshold current density of 6.7 x 10^11 A/m2 in a 10 nm-thick Ni81Fe19 wire with a width of 240 nm. The temperature was raised to 830 K for the current density of 7.5 x 10^11 A/m2, which is very close to the Curie temperature of bulk Ni81Fe19. When the current density exceeded 7.5 x 10^11 A/m2, an appearance of a multi-domain structure in the wire was observed by magnetic force microscopy, suggesting that the sample temperature exceeded the Curie temperature.Comment: 13 pages, 4 figure

Electric Resistance of Magnetic Domain Wall in NiFe Wires with CoSm Pinning Pads (SOLID STATE CHEMISTRY-Artificial Lattice Allolys)

A NiFe wire of 1μm width with hard magnetic CoSm pinning pads and Cu electrodes was prepared by electron-beam lithography and lift-off technique. Using the exchange interaction between the NiFe wire and CoSm pads, magnetic structures with and without magentic domain walls were realizecd at zero external field. The electric resistance of the wall state was smaller than that of the no-wall state. The difference of the resistance can be explained by the anisotropic magnetoresistance effect in the domain walls

Magnetoresistance of Bloch-Wall-Type Magnetic Structures Induced in NiFe/CoSm Exchange-Spring Bilayers (SOLID STATE CHEMISTRY-Artificial Lattice Alloys)

The magnetoresistance (MR) originating from a magnetic structure with gradually rotating magnetic moments was studied using soft-magnetic (NiFe)/hard-magnetic (CoSm) bilayers. The main feature of the MR curves was explained as anisotropic magnetoresistance (AMR) effect. It was found that a giantmagnetoresistance-( GMR)-type effect coexisted, although the effect was very small in comparison with the AMR effect