INELASTIC NEUTRON SCATTERING INVESTIGATION OF SPIN WAVES AND MAGNETIC INTERACTIONS IN α-Fe2O3
INELASTIC NEUTRON SCATTERING INVESTIGATION OF SPIN WAVES AND MAGNETIC INTERACTIONS IN α-Fe2O3
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α-Fe2O3 中自旋波和磁相互作用的非弹性中子散射研究
DOI：
10.1051/jphyscol:19711382
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发表时间：
1971
期刊：
影响因子：
--
通讯作者：
G. Shirane
中科院分区：
文献类型：
--
作者：
E. Samuelsen;G. Shirane
用中子非弹性散射方法研究了240和290° K温度下反铁磁α-Fe_2 O_3中的自旋波。我们在这里报告的声学分支在整个布里渊区的第一次测定和光学分支的第一次观察。后者在整个带中几乎没有色散，在带中心的能量为1125° K（97 meV）。在区域边界处，两个分支之间存在20至70° K的间隙。通过将数据拟合到色散关系的理论表达式，获得了通过汉密尔顿函数定义的海森堡相互作用参数Jm。对于前五个最近的邻居，获得了以下值：J1 = 6.0 ± 1.6° K，J2 = 1.6 ± 0.6° K，J3 = −29.7 ± 2.0° K，J 4 = −23.2 ± 1.0° K和J5 = −1.0 ± 1.0° K。与更远的邻居的相互作用被认为是弱的。在获得相互作用参数时，部分地调用了中子强度数据，因为两组参数几乎可以同样好地拟合能量数据，但它们预测了倒易空间某些区域中两个分支的不同相对强度。所有能量大于80° K的自旋波，包括整个光学分支，在261° K温度下不受Morin自旋翻转跃迁的影响。利用自旋波数据计算了亚晶格磁化强度、Neel和Curie Weiss温度、低温垂直磁化率和自旋波态谱密度。
[俄语文本忽略]
Spin waves in antiferromagnetic α-Fe2O3 have been studied at temperatures of 240 and 290° K by means of inelastic neutron scattering. We report here the first determination of the acoustical branch throughout the entire Brillouin zone and the first observation of the optical branch. The latter shows little dispersion throughout the zone, and has an energy of 1125° K (97 meV) at the zone centre. At the zone boundaries a gap of 20 to 70° K exists between the two branches. Heisenberg interaction parameters Jm defined through a Hamiltonian were obtained through fitting of the data to theoretical expressions for the dispersion relations. The following values were obtained for the first five nearest neighbours: J1 = 6.0 ± 1.6° K, J2 = 1.6 ± 0.6° K, J3 = −29.7 ± ± 2.0° K, J4 = −23.2 ± 1.0° K and J5 = −1.0 ± 1.0° K. Interactions to farther neighbours were found to be weak. Neutron intensity data were partly invoked in obtaining the interaction parameters, as two sets of parameters could fit the energy data almost equally well, but they predicted different relative intensities for the two branches in certain regions of the reciprocal space. All spin waves of energy larger than 80° K, including the entire optical branch, were found to be unaffected by the Morin spin-flip transition at 261° K temperature. The spin-wave data were used to calculate the sublattice magnetization, the Neel and the Curie-Weiss temperatures, the perpendicular susceptibility at low temperatures and the density of spin-wave state spectrum.
[Russian Text Ignored]