De Haas-van Alphen effect and magnetization in dodecaborides HoB12, ErB12 and TmB12

High-quality HoB12, ErB12 and TmB12 single crystals with the fcc UB12 structure are grown; field dependencies of their magnetization are measured up to 14 T; angular dependences of the magnetization in the (1 0 0) and (1 1 0) planes are calculated, and properties of their Fermi surfaces (FS) are studied using the de Haas-van Alphen (dHvA) effect. The angular dependences of the dHvA frequencies in the (1 0 0) and (1 1 0) planes are obtained and values of their effective cyclotron masses are determined. The oscillation frequencies lie in the range (11.7-127.3)x102 T, and cyclotron masses within the range (0.4-1.45)m0. For ErB12 and TmB12, we found branches in the oscillation spectrum that originated from FS fragments with spins along and opposed to the field, and the energy of the exchange interaction is estimated. Its value for the γ-branch in ErB12 is equal to 8.2 meV, and for the γ-, β- and θ-branches in TmB12; these values are 14.5, 28.5, and 18.3 meV, respectively