title: Critical Velocity in the Presence of Surface Bound States in Superfluid ^{3}He-B.
abstract: A microelectromechanical oscillator with a gap of 1.25  μm was immersed in superfluid ^{3}He-B and cooled below 250  μK at various pressures. Mechanical resonances of its shear motion were measured at various levels of driving force. The oscillator enters into a nonlinear regime above a certain threshold velocity. The damping increases rapidly in the nonlinear region and eventually prevents the velocity of the oscillator from increasing beyond the critical velocity which is much lower than the Landau critical velocity. We propose that this peculiar nonlinear behavior stems from the escape of quasiparticles from the surface bound states into the bulk fluid.
authors.affiliation: Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA.
authors.forename: P
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA.
authors.forename: W G
authors.initials: WG
authors.lastname: Jiang
authors.affiliation: Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Barquist
authors.affiliation: Department of Physics, University of Florida, Gainesville, Florida 32611-8440, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong.
authors.forename: H B
authors.initials: HB
authors.lastname: Chan