Spin-state blockade in Te$^{6+}$-substituted electron-doped LaCoO$_{3}$*

Perovskite-type LaCoO$_{3}$ (Co$^{3+}$: $d^{6})$ is a rare inorganic material with sensitive and characteristic responses among low, intermediate, and high spin states. For example, in insulating nonmagnetic low-spin states below about 20 K, light hole doping (Ni substitution) induces much larger magnetization than expected; over net 10$\mu_{B}$/hole (5$\mu_{B}$/Ni) for 1$\mu_{B}$/hole (1$\mu_{B}$/Ni), in which the nearly isolated dopants locally change the surrounding Co low-spin states to magnetic ones and form spin molecules with larger total spin [1-4]. Further, the former is isotropic, whereas the latter exhibits characteristic anisotropy probably because of Jahn-Teller distortion [2]. In contrast, for electron doping, relatively insensitive spin-state responses were reported, as in LaCo(Ti$^{4+})$O$_{3}$, but are not clarified, and are somewhat controversial. Here, we present macroscopic measurement data of another electron-doped system LaCo(Te$^{6+})$O$_{3}$ and discuss the spin-state responses. -- Refs. [1] S. Yamaguchi et al., PRB (1996). [2] K. Tomiyasu et al., PRB (2013). [3] A. Podlesnyak et al., PRL (2008). [4] Y. Ju et al., J. Supercond. Nov. Magn. (2013).