GROUND-STATE PROPERTIES OF THE TM+3 ION TMNI10SI2

The paramagnetic susceptibility and magnetisation measurements of TmNi 10Si2 and YNi10Si2 were utilised to establish the ground state of the Tm+3 rare earth ion. The Ni contribution to the total susceptibility w as considered as Pauli paramagnetism type, The Gamma(t4)((2)) doublet is the ground state separated by 15 K from first excited singlet Gamma (t4)((1)) The magnetic moment associated with the groundstate doublet agrees well with magnetisation saturation data at 4.2 K. The overall c rystal field splitting 70 K is in agreement with available neutron dif fraction data.