1211.3529 (T. Taniguchi et al.)

Long-range order and spin liquid states of polycrystalline
Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$    [PDF]

T. Taniguchi, H. Kadowaki, H. Takatsu, B. Fåk, J. Ollivier, T. Yamazaki, T. J. Sato, H. Yoshizawa, Y. Shimura, T. Sakakibara, T. Hong, K. Goto, L. R. Yaraskavitch, J. B. Kycia

Low-temperature states of polycrystalline samples of a frustrated pyrochlore oxide Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$ have been investigated by specific heat, magnetic susceptibility, and neutron scattering experiments. We have found that this system can be tuned from a long-range ordered state ($x > x_{\text{c}}$) to a spin-liquid state by a minute change of $x$. Specific heat shows a sharp peak at a phase transition at $T_{\text{c}}= 0.5$ K for $x=0.005$. Inelastic neutron scattering shows that the crystal field ground state doublet of Tb$^{3+}$ splits into two singlets below $T_{\text{c}}$, suggesting a cooperative Jahn-Teller transition due to a magneto-elastic coupling, accompanied by a small antiferromagnetic ordering.

View original: http://arxiv.org/abs/1211.3529