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1.
Effects of Ga substitution for Sn on the structure and magnetic properties of TbMn6Sn6-xGax (x=0.0-1.2) compounds have been investigated by means of x-ray diffraction, magnetization measurement and 119Sn M?ssbauer spectroscopy. The substitution of Ga for Sn results in a decrease in lattice constants and unit-cell volumes. The magnetic ordering temperature decreases monotonically with increasing Ga content from 423 K for x=0.0 to 390 K for x=1.2. At room temperature, the easy magnetization direction changes from the c-axis to the ab-plane. This variation implies that the substitution of Ga for Sn leads to a decrease in the c-axis anisotropy of the Tb sublattice. An increase in the non-magnetic Ga concentration results in a monotonic decrease of the spontaneous magnetization Ms at room temperature. Since there are three non-equivalent Sn sites, 2c (0.33, 0.67,0), 2d (0.33, 0.67,0.5) and 2e (0,0,0.34) in the TbMn6Sn6-xGax compounds, the 119Sn M?ssbauer spectra of the TbMn6Sn6 and TbMn6Sn5.4Ga0.6 compounds can be fitted by three sextets. The hyperfine fields (HFs) decrease in the order of HF(2d)>HF(2e)>HF(2c), which is in agreement with the magnetic structure. 相似文献
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根据实验数据,构造了接近实际纳米晶永磁Pr2Fe14B的样品,用微磁学有限元法进行了模拟计算.计算结果表明,晶界处各向异性的下降会导致矫顽力减小、剩磁值增大,而晶界处交换作用常数的减小则会使剩磁值减小、矫顽力增大.通过对实验样品的模拟研究发现,晶界处各向异性和交换作用常数的共同减小能够同时拟合出真实的矫顽力和剩磁值.模拟计算与实验在退磁曲线形状上的差距则说明模拟还存在不足.
关键词:
纳米晶永磁
磁滞回线
矫顽力
剩磁 相似文献
3.
散裂中子源是基于质子加速器产生的高能质子轰击重金属靶造成重金属原子散裂从而提供高脉冲中子通量的平台型大科学装置,散裂中子源在众多学科领域,特别是物质科学领域得到了广泛的应用,结合目前正在筹备阶段的北京散裂中子源(BSNS)项目的“第二届散裂中子源多学科应用研讨会”于2005年7月27日—29日在北京中国科学院物理研究所召开。 相似文献
4.
An investigation of phase separation by magnetic force microscopy in La0.45Sr0.55MnO3-δ(δ≈0.01) 下载免费PDF全文
We have found phase separation in La0.45Sr0.55MnO3-δ (LSMO) by means of electron spin resonance, magnetic force microscopy (MFM) and magnetic measurements. Ferromagnetic and antiferromagnetic phases can coexist at low temperatures, and ferromagnetic and paramagnetic phases coexist when the temperature lies between the Néel and Curie temperatures. The size and shape of the ferromagnetic phases (the minority phases) was first observed directly from MFM images. It is suggested that the phase separation in LSMO is not the charge segregation type, but an electroneutral type due perhaps to the nonuniform distribution of oxygen vacancies. 相似文献
5.
STRUCTURE, MAGNETIC PROPERTIES AND GIANT MAGNETORESISTANCE OF YMn6Sn6-xGax (x=0-0.6) COMPOUNDS 下载免费PDF全文
Structure, magnetic and transport properties of YMn6Sn6-xGax (0≤x≤0.6) compounds with a HfFe6Ge6-type structure were investigated. It was found that the Ga substitution leads to a contraction of the unit-cell volume. A transition from an antiferromagnetic to a ferromagnetic (or ferrimagnetic) state can be observed for samples (0.1≤x≤0.2) with increasing temperature. The antiferro-ferromagnetic transition for samples with x≤0.2 can also be induced by an external field. The required field is very low, and decreases with increasing Ga concentration. More Ga concentration (x≥0.3) leads to the samples being ferromagnetic in the whole temperature range below the Curie temperature. The Ga substitution weakens the interlayer magnetic coupling between the Mn spins. Corresponding to the metamagnetic transition, a magnetoresistance as large as 32% under a field of 5 T was observed at 5 K for the sample with x=0.2. 相似文献
6.
Magnetic properties and coercivity mechanism of precipitation-hardened Gd-Co based ribbons 下载免费PDF全文
Gd(Co_{0.88-x}Cu_xFe_{0.09}Zr_{0.03})_z ribbons with x=0.075-0.200 and z=6.4-7.7 have been prepared by a melt-spinning technique. A cellular microstructure consisting of 2:17 cells surrounded by the 1:5 cell boundary phase is obtained after precipitation hardening. The dependence of room temperature coercivity on the heat treatment process suggests that the long-time isothermal aging is not helpful for the development of magnetic properties. Positive temperature coefficient of remanence from room temperature to about 673K is typical for all samples, while positive temperature coefficient of coercivity is obtained only in ribbons with low Cu content. The coercivity mechanism of the precipitation-hardened ribbons at different temperatures is also discussed. 相似文献
7.
畴壁钉扎模型的矫顽力可以表示为Hc=αpink2K1/μ0Ms-NeffMs,计算了微结构参数αpink随面缺陷内磁性参数A′和K′1的变化情况.结果表明,αpink可以在很宽的范围里取值.结合纳米单相Nd2Fe14B磁体,研究了晶粒边界的磁性参数和晶界厚度对αpink的影响,当A′/A=05,K′1/K1=01,以及晶界厚度r0=332nm时,αpink最大.同时研究了纳米复相Nd2Fe14B/α-Fe磁体的αpink随α-Fe晶粒尺寸r0的变化情况,当r0=7nm时,αpink最大.
关键词:
面缺陷
矫顽力
钉扎机理
纳米晶 相似文献
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9.
用快淬方法制备了Pr10Fe74-xCo10+xC4B4 (x=0,2,4,6,8) 条带,研究了成分和工艺对条带磁性能的影响.实验发现,当x=2,带速是20 m·s-1时,条带的磁性能最佳,其剩磁Jr=0.94 T,矫顽力μ0 iHc=0.96 T,最大磁能积 (BH)max=127.32 kJ·m-3.通过Henkel-plot分析,发现x=2,带速为20 m·s-1的样品中的晶间交换作用最强,因而能获得最佳的磁性能. 相似文献
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