  Cavity magnomechanics using mechanical degrees of freedom in ferromagnetic
crystals provides a powerful platform for observing many interesting classical
and quantum nonlinear phenomena in the emerging field of magnon spintronics.
However, to date, the generation and control of chaotic motion in a cavity
magnomechanical system remain an outstanding challenge due to the inherently
weak nonlinear interaction of magnons. Here, we present an efficient mechanism
for achieving magnomechanical chaos, in which the magnomechanical system is
coherently driven by a two-tone microwave field consisting of a pump field and
a probe field. Numerical simulations show that the relative phase of the two
input fields plays an important role in controlling the appearance of chaotic
motion and, more importantly, the threshold power of chaos is reduced by 6
orders of magnitude from watts to microwatts. In addition to providing insight
into magnonics nonlinearity, cavity magnomechanical chaos will always be of
interest because of its significance both in fundamental physics and potential
applications ranging from ultra-low threshold chaotic motion to chaos-based
secret information processing.
