Affiliation: | a Department of Physics, QwaQwa Campus, University of the Free State, Phuthaditjhaba, Private Bag X 13, 9866, South Africa b f-Electron Magnetism and Heavy-Fermion Physics Research Programme, School of Physics, University of the Witwatersrand, Private Bag 3, P.O. Wits 2050, Johannesburg, South Africa c Department of Physics, University of Johannesburg, P.O. Box 524, Auckland Park 2006, Johannesburg, South Africa |