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Abstract

The nonlinear response to an ac magnetic field with and without
parametric pumping was studied experimentally on a rod-like beryllium
single crystal at low temperatures in a quantizing magnetic field
applied parallel to the hexagonal axis. At low temperatures (<= 3 K)
giant parametric amplification of the nonlinear response is observed in
narrow windows near de Haas-van Alphen (dHvA) beating antinodes, where
the amplitude of the magnetic oscillations is maximal. This effect is
of threshold character with respect to the amplitude of the dHvA
oscillations and occurs as a result of a diamagnetic phase transition
of a strongly correlated electron gas into nonuniform state, with the
formation of Condon domain structure. It is shown that the nonuniform
phase appears periodically in a magnetic field. The components of the
rectified signal field reproduce the envelope of H-T critical curves
and can be used for reconstruction of diamagnetic phase diagrams. (c)
2006 American Institute of Physics.