Band Jahn-Teller instability and formation of valence bond solid in a mixed-valent spinel oxide LiRh2O4.
We have synthesized a new spinel oxide LiRh2O4 with a mixed-valent configuration of Rh3+ and Rh4+. At room temperature, it is a paramagnetic metal, but on cooling, a metal-insulator transition occurs and a valence bond solid state is formed below 170 K. We argue that the formation of valence bond solid is promoted by a band Jahn-Teller transition at 230 K and the resultant confinement of t_{2g} holes within the xy band. The band Jahn-Teller instability is also responsible for the observed enhanced thermoelectric power in the orbital-disordered phase above 230 K.
Okamoto
Yoshihiko
Y
RIKEN (The Institute of Physical and Chemical Research), Hirosawa 2-1, Wako 351-0198, Japan.
Niitaka
Seiji
S
Uchida
Masaya
M
Waki
Takeshi
T
Takigawa
Masashi
M
Nakatsu
Yoshitaka
Y
Sekiyama
Akira
A
Suga
Shigemasa
S
Arita
Ryotaro
R
Takagi
Hidenori
H