Infrared Absorption and Raman Scattering by Two‐Magnon Processes in NiO
Infrared Absorption and Raman Scattering by Two‐Magnon Processes in NiO
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DOI：
10.1063/1.1660309
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发表时间：
1971-03
影响因子：
3.2
通讯作者：
R. Dietz;G. Parisot;A. Meixner
中科院分区：
文献类型：
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作者：
R. Dietz;G. Parisot;A. Meixner
在绿色和黑色（来自过量氧）NiO单晶中，两个磁振子的温度依赖性拉曼散射已经被观察到，在1.4°K时达到1555 cm−1的峰值。主要的亚晶格间交换J2=148 cm−1可以很好地描述能带的形状，这与中子散射得到的J2=153 cm−1非常吻合拉曼散射的高频截止点位于1900 cm−1附近，与J1=0的双磁振子接合密度在176 cm−1附近的截止点一致。吸收线2在1940 cm−1处达到峰值，根据这一数据重新检查了吸收线2，发现在2460 cm−1处高频侧有一个截止点，在拉曼散射峰附近有一个阈值。这些数据支持一个吸收带的模型，其中两个磁振子与一个光子同时产生，在k=0时，截断对应于两个带边界磁振子和一个580 cm−1的L0声子的产生。这种双磁振子跃迁的声子边带可能来源于…
Temperature‐dependent Raman scattering by two magnons has been observed in both green and black (from excess oxygen) NiO single crystals, peaking at 1555 cm−1 at 1.4°K. The shape of the band is reasonably well described by a dominant intersublattice exchange of J2=148 cm−1, in excellent agreement with the value J2=153 cm−1, obtained from neutron scattering.1 The high‐frequency cutoff of the Raman scattering lies near 1900 cm−1 in agreement with the J1=0 two‐magnon joint density‐of‐states cutoff at 176 cm−1. The absorption line2 peaking at 1940 cm−1 has been reexamined in light of this data, and is found to exhibit a cutoff on the high‐frequency side at 2460 cm−1, and a threshold near the peak of the Raman scattering. These data support a model for the absorption band in which two magnons are created simultaneously with a photon, with the cutoff corresponding to the creation of two zone boundary magnons and an L0 phonon of 580 cm−1 at k=0. Such a phonon sideband of a two‐magnon transition probably derives ...