  We report magnetoresistance oscillations in high magnetic fields, B, up to 45
T and over a wide range of temperature in the Mott-like system Ca3Ru2O7. For B
rotating within the ac-plane, slow and strong Shubnikov-de Haas (SdH)
oscillations periodic in 1/B are observed for T&#8804;1.5 K in the presence of
metamagnetism. These oscillations are highly angular dependent and intimately
correlated with the spin-polarization of the ferromagnetic state. For B||[110],
oscillations are also observed but periodic in B (rather than 1/B) which
persist up to 15 K. While the SdH oscillations are a manifestation of the
presence of small Fermi surface (FS) pockets in the Mott-like system, the
B-periodic oscillations, an exotic quantum phenomenon, may be a result of
anomalous coupling of the magnetic field to the t2g-orbitals that makes the
extremal cross-section of the FS field-dependent.
