Slow spin relaxation in a highly polarized cooperative paramagnet.
We report measurements of the ac susceptibility of the cooperative paramagnet Tb2Ti2O7 in a strong magnetic field. Our data show the expected saturation maximum in chi(T) and also an unexpected frequency dependence of this peak at low frequencies (<1 Hz), suggesting very slow spin relaxations are occurring. Measurements on samples diluted with nonmagnetic Y3+ or Lu3+ and complementary measurements on pure and diluted Dy2Ti2O7 strongly suggest that the relaxation is associated with dipolar spin correlations, representing unusual cooperative behavior in a paramagnetic system.
Department of Physics and Materials Research Institute, Pennsylvania State University, University Park Pennsylvania 16802, USA.
B G
BG
Ueland
G C
GC
Lau
R J
RJ
Cava
J R
JR
O'Brien
P
P
Schiffer