Magnetostriction of the spin-peierls compound CuGeO3

The magnetostriction lambda of spin-Peierls compound CuGeO3 was measured in magnetic field up to 18 T both above, and below the transition temperature T-sp = 14.3 K. In uniform phase at T > T-sp lambda in b-c plane is negative and isotropic, while in dimerized phase at T < T-ap lambda is positive and anisotropic (lambda(b) > lambda(c)). At low temperatures lambda increases sharply at transition from dimerized to magnetic phase.