1202.1107 (K. Matsuhira et al.)

Spin Dynamics at Very Low Temperature in Spin Ice Dy$_2$Ti$_2$O$_7$    [PDF]

K. Matsuhira, C. Paulsen, E. Lhotel, C. Sekine, Z. Hiroi, S. Takagi

We have performed AC susceptibility and DC magnetic relaxation measurements
on the spin ice system Dy$_2$Ti$_2$O$_7$ down to 0.08 K. The relaxation time of
the magnetization has been estimated below 2 K down to 0.08 K. The spin
dynamics of Dy$_2$Ti$_2$O$_7$ is well described by using two relaxation times
($\tau_{\rm S}$ (short time) and $\tau_{\rm L}$ (long time)). Both $\tau_{\rm
S}$ and $\tau_{\rm L}$ increase on cooling. Assuming the Arrhenius law in the
temperature range 0.5-1 K, we obtained an energy barrier of 9 K. Below 0.5 K,
both $\tau_{\rm S}$ and $\tau_{\rm L}$ show a clear deviation from the thermal
activated dynamics toward temperature independent relaxation, suggesting a
quantum dynamics.

View original: http://arxiv.org/abs/1202.1107