Acoustic quantum oscillations were observed in the sound velocity change of (C11-C>12)/2 and C44 modes. The observed oscillations were of the degenerate ρ3 and ρ4 branches from the interconnecting necks along the Σ lines in the simple cubic Brillouin zone. Clear evidence was found for the rotational invariance effect in the quantum oscillations of the (C11-C12)/2 mode and the anisotropy effect of the C44 mode.

Acoustic De Haas-Van Alphen Effect and Rotational Invariance of LaB6. Suzuki, T., Goto, T., Fujimura, T., Kunii, S., Suzuki, T., Kasuya, T.: Journal of Magnetism and Magnetic Materials, 1985, 52[1-4], 261-3