Hongwei QIN
,
Jifan HU
,
Juan CHEN
,
Hongdong NIU
,
Luming ZHU
,
Zhuo WANG
材料科学技术（英文）
by Tb in (La1-xTbx)0.67Sr0.33MnO3, the room temperature magnetoresistance △R/R0 drops at first, then undergoes an increase near x≈0.1, and finally drops again. The value of room temperature magnetoresistance at a field H=12 kOe for (La1-xTbx)0.67Sr0.33MnO3 is -3.56%. The enhancement of the room temperature magnetoresistance induced by an appropriate Tb substitution in (La1-xTbx)0.67Sr0.33MnO3 is correlated with the shifts of the Curie temperature and metal-insulator temperature to near room temperature. The drop of the room temperature magnetoresistance at large Tb doping-contents may be due to its lower TC and TMI far from the room temperature.
关键词:
Magnetoresistance
,
null
,
null
,
null
Zhengyou ZHOU
,
Xiaoshan WU
,
Jun DU
金属学报(英文版)
doi:10.1016/S1006-7191(08)60070-8
Effects of soft-magnetic MnZn ferrite (Mn0.5Zn0.5Fe2O4, MZF) and hard-magnetic Ba
ferrite (BaO?6Fe2O3, BaM) on the structure and magnetic transport properties of [La2/3Sr1/3MnO3]
(LSMO)/(x) [ferrites] (ferrites=MZF, BaM) composites have been investigated. It was found that the inclusion of MZF phase reduces
magnetization and ferromagnetic-paramagnetic transition temperature (Tc) of the composites. With increasing the content of the
dopants, the high-temperature magnetoresistance (MR) decreases, whereas low-temperature MR increases and reaches 42% at 150~K and
x=0.1. However, for the LSMO/BaM composites, magnetization and ferromagnetic-paramagnetic transition temperature (Tc)
decrease firstly as x<5 %, and then increase as x>5 %. The resistivity of the composites increases by five orders of magnitude
at x=1 % and is out of measured range at x=5 %. High magnetic field has little effect on the resistivity and magnetoresistance for
the composites with x>5 %, which may originate from the pinning effect of BaM grains.
关键词:
Composites
,
null
,
null
,
null
Gang JI
,
Ze ZHANG1
,
Yanxue CHEN
,
Shishen YAN
,
Yihua LIU
,
Liangmo MEI
金属学报(英文版)
doi:10.1016/S1006-7191(08)60083-6
[FeNi(3~nm)/Zn1- xCoxO(3~nm)]2/ZnO(d nm)/[Zn1-xCoxO(3 nm)/Co(3 nm)]2 (d=3 and 10) semiconductor junctions were prepared by magnetron sputtering system and photolithography. The spin valve effect was observed in these junctions because the utility of the ferromagnetic composite layers acted as soft and hard magnetic layers. The electrical detection was performed by measuring the magnetoresistance of these junctions to investigate the current spin polarization αsc in the ZnO layer and the spin injection efficiency η of spin-polarized electrons. αsc was reduced from 11.7% (and 10.5%) at 90 K to 7.31 % (and 5.93 %) at room temperature for d=3 (and d=10). And η was reduced from 39.5 % (and 35.5 %) at 90 K to 24.7 % (and
20.0 %) at room temperature for d=3 (and d=10).
关键词:
Spin injection
,
null
,
null
,
null
,
null
邓海金
,
李军红
,
孙立
,
李明
新型炭材料
doi:10.3969/j.issn.1007-8827.2006.03.004
研究了四种C/C复合材料的磁电阻与测试位向的关系.其中每种试样具有不同结构的预制体,并经过2400℃～2800℃热处理.实验结果表明,这四种材料的磁电阻-测试位向曲线形状完全不同,而同一材料的曲线形状基本相同,并且与热处理测试温度和磁场强度无关.经傅里叶函数分析,材料的磁电阻-测试位向曲线形状与其预制体纤维的方向有关.
关键词:
炭/炭复合材料
,
结构
,
磁电阻
,
位向
,
石墨化
Gang JI
,
Shishen YAN
,
Yanxue CHEN
,
Qiang CAO
,
Wei XIA
,
Yihua LIU
,
Liangmo MEI
,
Ze ZHANG
,
null
材料科学技术（英文）
2×(FeNi/CoZnO)/ZnO/(CoZnO/Co) ×2 spin-injection devices were prepared by sputtering and photo-lithography. In the devices, two composite magnetic layers 2×(FeNi/CoZnO) and (CoZnO/Co) ×2 with different coercivities were used to fabricate the ZnO-based semiconductor spin valve. Since the CoZnO ferromagnetic semiconductor layers touched the ZnO space layer directly, the significant spin injection from CoZnO into ZnO was observed by measuring the magnetoresistance of the spin-injection devices. The magnetoresistance reduced linearly with increasing temperature, from 1.12% at 90 K to 0.35% at room temperature.
关键词:
Spin injection
,
磁电阻
,
铁磁性半导体
Yanxue CHEN
,
Shouguo WANG
,
Liangmo MEI
,
Kungwon Rhie
,
Sangjin Byeun
材料科学技术（英文）
A series of CoFe (4 nm)/ Cu(X nm) Al (Y nm)/ CoFe(6 nm) samples have been prepared at room temperature. An exponential decay of the GMR (Giant Magnetoresistance) with Y was observed for fixed X=2nm. The characteristic decay parameter of Al is obtained to be about 0.26nm, which is rather close to 1 monolayer for Al. A coexistant state of GMR and AMR (anisotropic magnetoresistance) was observed when Y=2 nm. As the Cu spacer is replaced by Al layer, only AMR effect dominates. The experimental data further underline the important role played by the nonmagnetic spacers.
关键词:
CoFe
,
null
,
null
