Experimental Investigation of the Cooperative Jahn-Teller Effect in TmCd
Experimental Investigation of the Cooperative Jahn-Teller Effect in TmCd
复制标题
TmCd 协同 Jahn-Teller 效应的实验研究
DOI：
--
复制
发表时间：
1973
期刊：
影响因子：
--
通讯作者：
J. Maita
中科院分区：
文献类型：
--
作者：
B. Lüthi;M. Mullen;K. Andres;E. Bucher;J. Maita
TmCd has the CsCl structure and shows a Jahn-Teller distortion to a tetragonal structure at ${T}_{a}=3.16$ K. Specific-heat, electrical-resistance, and elastic measurements show that the ground state of the ${mathrm{Tm}}^{3+}$ ion is a nonmagnetic ${ensuremath{Gamma}}_{3}$ doublet. The next-higher excited level is at approximately 20 K. We do not find evidence for magnetic ordering down to 40 mK. The susceptibility and high-field magnetization can be interpreted with these crystal-field levels without taking exchange into account. The elastic ${c}_{44}$ mode shows a small anomaly of 0.9% at ${T}_{a}$, whereas the ${c}_{11}ensuremath{-}{c}_{12}$ mode shows strong softening below 100 K of 33% down to ${T}_{a}$. We can interpret the temperature dependence of this mode quantitatively. High magnetic fields have a profound influence on these elastic constants and electrical resistivity. We find an apparent increase of ${T}_{a}$ for magnetic fields applied in the [100] direction and somewhat smaller effects for other directions. We explain this effect tentatively by showing that the first-order transition is shifted in high fields to higher temperatures and that the discontinuity in the order parameter diminishes continuously with increasing field.
TmCd has the CsCl structure and shows a Jahn-Teller distortion to a tetragonal structure at ${T}_{a}=3.16$ K. Specific-heat, electrical-resistance, and elastic measurements show that the ground state of the ${mathrm{Tm}}^{3+}$ ion is a nonmagnetic ${ensuremath{Gamma}}_{3}$ doublet. The next-higher excited level is at approximately 20 K. We do not find evidence for magnetic ordering down to 40 mK. The susceptibility and high-field magnetization can be interpreted with these crystal-field levels without taking exchange into account. The elastic ${c}_{44}$ mode shows a small anomaly of 0.9% at ${T}_{a}$, whereas the ${c}_{11}ensuremath{-}{c}_{12}$ mode shows strong softening below 100 K of 33% down to ${T}_{a}$. We can interpret the temperature dependence of this mode quantitatively. High magnetic fields have a profound influence on these elastic constants and electrical resistivity. We find an apparent increase of ${T}_{a}$ for magnetic fields applied in the [100] direction and somewhat smaller effects for other directions. We explain this effect tentatively by showing that the first-order transition is shifted in high fields to higher temperatures and that the discontinuity in the order parameter diminishes continuously with increasing field.