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利用各种实验手段对M52Mn24Ga24单晶中马氏体变体的择优取向进行了表征.针对金相观察、磁场干预的相变应变、磁感生应变等实验结果,分析了马氏体相变过程变体自发择优取向和磁诱导择优取向的机理.根据不同方向磁场干预相变应变的结果,计算了Ni52Mn24Ga24单晶中等效取向内应力的大小约为2.45 MPa.从变体择优取向造成的有效弹性和磁畴分布两个方面,对单晶样品在[001]和[010]两个等价的晶体学方向上磁感生应变特性的差别,包括最大应变值、饱和场、滞后效应和起始磁场数值的参数,进行了分析和讨论. 相似文献
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Structure and magnetic properties of a new single-molecule magnet [Mn11Fe1O12 (CH3COO)16(H2O)4].2CH3COOH.4H2O 下载免费PDF全文
A new single-molecule magnet [Mn11Fe1O12 (CH3COO)16(H2O)4]?2CH3COOH?4H2O (Mn11Fe1) has been synthesized.The structure has been studied by the single crystal x-ray diffraction. The difference of Jahn--Teller distortion between Fe3+ and Mn3+ ion reveals that Fe3+ ion substitutes for Mn3+ ion on the Mn(3)
sites in the Mn12 skeleton. The temperature dependence of the magnetization gives a blocking temperature TB=1.9K for Mn11Fe1. Based on the magnetization process analysis of the crystal at T=2K, we suggest that Mn11Fe1 has the ground state with a total spin S= 11/2. 相似文献
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The thermally assisted resonant tunnelling in a single crystal (Mn_{0.96}Cr_{0.04})12-ac is studied in this paper. The obtained hysteresis loops at seven different temperatures between 1.8 and 3K show obvious dependence on temperature. The magnetization steps occur at specific field values of nH_R with H_R≈0.46T, which are approximately independent of the temperature. As the temperature decreases, the area enclosed in the hysteresis loops and the actual number n of the resonances increase, which provides clear evidence of thermally assisted resonant tunnelling in (Mn_{0.96}Cr_{0.04})12-ac. 相似文献
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Resonant tunnelling of the magnetization in molecular crystal of [(Mn1-xCrx)12O12 (CH3COO)16(H2O)4]·2CH3COOH·4H2O(x=0,0.03,0.04,0.05) 下载免费PDF全文
The quantum tunnelling of magnetization (QTM) in single crystals of the single molecule magnet (Mn1-xCrx)12- Ac (x=0, 0.03, 0.04, 0.05) has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core. 相似文献
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Resonant tunnelling of the magnetization in molecular crystal of [(Mn1-xCrx)12O12 (CH3COO)16(H2O)4]·2CH3COOH·4H2O(x=0,0.03,0.04,0.05) 下载免费PDF全文
The quantum tunnelling of magnetization (QTM) in single crystals of the single molecule magnet (Mn1-xCrx)12- Ac (x=0, 0.03, 0.04, 0.05) has been investigated. In comparison with its parent Mnl2-Ac, a greater rate of magnetization relaxation and a lower effective potential-energy barrier have been observed in Cr-doping samples. This modulation of QTM due to the Cr-doping could be attributed to the small change of Sz due to the smaller spin of Cr itself and additional intrinsic but distributed transverse and longitudinal anisotropy raised by a subtle change of the local environment in the magnetic Mn12 core. 相似文献
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This paper investigates the single-molecule magnets of pure and Cr/Fe-doped Mn12-Ac. The components of the mixed crystals are identified by AC susceptibility technique. The ground-state spin and anisotropy parameters of doped Mn12-Ac are obtained: (i) MnllCr-Ac (S=19/2, D=0.62K, B=0.0009K, A=63K), and (ii) Mn11Fe-Ac (S=21/2, D=0.39 K, B=0.001 K, △=55 K). The single-ion origin of the magnetic anisotropy is discussed. 相似文献
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In this paper neutron diffraction experiments were performed for Fe-substituted Mn12 in order to determine the sites of Fe atoms. The results of structure refinements for the sample with our accessed highest Fe content showed that all Fe atoms occupied Mn(3) sites in the Mn12 skeleton. The x-ray absorption fine structure experiments as well as multiple scattering simulations gave the same result. Thus we concluded that Fe atoms only occupied Mn(3) sites. This conclusion also means that Fe-substituted Mn12 series only includes the four single-molecule magnets of [Mn12-xFexO12(CH3COO)16(H2O)4]·2CH3COOH·4H2O (x = 1, 2, 3, and 4), denoted by Mn11Fe1, Mn10Fe2, MngFe3, and Mn8Fe4, respectively. 相似文献
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