Magnetic Excitations and the Cooperative Jahn-Teller Transition in PrCu2

The structural distortion in PrCu//2 below the Jahn-Teller transition at T//D equals 7. 3 K has been measured by neutron diffraction. The primary order parameter is found to be the e//z//x strain of the orthorhombic unit cell. A dipole transition to the second excited crystal field level is also observed.

The dispersion of this excitation shows that the exchange interaction is antiferromagnetic nuclear ordering reported below 54 mK.