Anisotropy of the linear and quadratic magnetic birefringence in rare-earth semiconductors (γ-Ln2S3 (Ln=Dy3+, Pr3+, Gd3+, La3+)
Anisotropy of the linear and quadratic magnetic birefringence in rare-earth semiconductors (γ-Ln2S3 (Ln=Dy3+, Pr3+, Gd3+, La3+)
复制标题
稀土半导体中线性和二次磁双折射的各向异性 (γ-Ln2S3 (Ln=Dy3+, Pr3+, Gd3+, La3+)
DOI：
10.1134/1.1378175
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发表时间：
2001
影响因子：
1.1
通讯作者：
B. Krichevtsov
中科院分区：
文献类型：
--
作者：
B. Krichevtsov
研究了非中心对称立方（对称级Td）稀土（RE）半导体γ-Ln2S3（Ln=Dy3+、Pr3+、Gd3+、La3+）中磁线性双折射（MLB）的场和角度依赖性。 Dy2S3 和 Pr2S3 中 MLB 的场依赖性是两种贡献的组合，即相对于磁感应强度 B 的二次贡献和线性贡献，两者都具有很强的各向异性。与波长 λ=633 nm 处的 Cotton-Mouton 效应表现相关的二次双折射在 Dy2S3 中通过值 β=1.5 deg/(cm T2) 和各向异性参数 a=-0.7 表征，在 Pr2S3 中通过 β=0.2 deg/(cm T2) 和 a=2 表征。 Dy2S3 和 Pr2S3 中由磁场引起的空间色散引起的不可逆 MLB 分别达到 γ 0.55 和 0.71 deg/(cm T)。描述 Bikj 型对介电张量 εij(ω,k,B) 的贡献的 γijkl 张量的参数 A 和 g 之间的关系在 Dy2S3 中（以及在含有 3d 离子的方硼石晶体中）为 A=2g，这是光频率范围内二阶磁电介电常数表现的特征。在Pr2S3中，关系A=3.3gi是附加四极机构表现的证据。 Ln2S3 和磁性半导体 Cd1−xMnxTe 中的 Cotton-Mouton 效应和法拉第效应的比较显示了这些系统之间的主要区别，并表明 Ln2S3 中的两种现象都是由 RE 离子中的光学跃迁决定的，而不是由带间或激子跃迁决定的。通过比较 Ln2S3、电介质 Dy3Ga5O12 和 Dy3Al5O12 单晶立方石榴石以及 Dy2O3 中的 Cotton-Mouton 效应表现也证实了这一点。对与局部互配置光学跃迁 4fN→ 4fN−15din RE 离子表现相关的非互易 MLB 机制的分析表明，与 Cotton-Mouton 和法拉第效应相反，这种现象是由作用于 Ln2S3 中 RE 离子的晶体场奇数分量的存在引起的。在 Gd2S3 和反磁性 Ln2S3 中，在 T=294 K 时，既没有出现 Cotton-Mouton 效应，也没有出现不可逆 MLB，这可以通过一方面 S 态离子和反磁性离子的磁光现象的不同微观机制来解释，另一方面可以通过具有非零轨道矩的 RE 离子的磁光现象的不同微观机制来解释。
The field and angular dependence of the magnetic linear birefringence (MLB) in noncentrosymmetric cubic (symmetry classTd) rare-earth (RE) semiconductors γ-Ln2S3(Ln=Dy3+, Pr3+, Gd3+, La3+) was studied. The field dependence of the MLB in Dy2S3and Pr2S3is a combination of two contributions, quadratic and linear with respect to the magnetic inductionB, both possessing a strong anisotropy. The quadratic birefringence related to the Cotton-Mouton effect manifestations at a wavelength of λ=633 nm is characterized in Dy2S3by the value of β=1.5 deg/(cm T2) and the anisotropy parametera=−0.7 and in Pr2S3, by β=0.2 deg/(cm T2) anda=2. The non-reciprocal MLB caused by the magnetic-field-induced spatial dispersion reaches γ 0.55 and 0.71 deg/(cm T) in Dy2S3and Pr2S3, respectively. The relationship between parametersAandgof the γijkltensor describing contributions of theBikjtype to the dielectric tensor εij(ω,k,B) isA=2g in Dy2S3(as well as in boracite crystals containing 3d ions), which is characteristic of the second-order magnetoelectric permittivity manifestations in the optical frequency range. In Pr2S3, the relationshipA=3.3gis evidence of manifestations of the additional quadrupole mechanism. A comparison of the Cotton-Mouton and Faraday effects in Ln2S3and in magnetic semiconductors Cd1−xMnxTe shows a principal difference between these systems and indicates that both phenomena in Ln2S3are determined by the optical transitions in RE ions rather than by the interband or exciton transitions. This is also confirmed by the comparison of the Cotton-Mouton effect manifestations in Ln2S3, in dielectric Dy3Ga5O12and Dy3Al5O12single crystal cubic garnets, and in Dy2O3. An analysis of the non-reciprocal MLB mechanisms related to manifestations of the local interconfiguration optical transitions 4fN→ 4fN−15din RE ions showed that this phenomenon, in contrast to the Cotton-Mouton and Faraday effects, is caused by the presence of odd components of the crystal field acting upon the RE ion in Ln2S3. In Gd2S3, as well as in diamagnetic Ln2S3, neither the Cotton-Mouton effect nor the non-reciprocal MLB are manifested atT=294 K, which is explained by different microscopic mechanisms of the magnetooptical phenomena for ions in the S-state and diamagnetic ions, on the one hand, and RE ions with nonzero orbital moment, on the other hand.