The glassy response of double torsion oscillators in solid ⁴He

Single and double torsion oscillators have been used to measure the anomalous change in resonant frequency and accompanying dissipation in solid ⁴He. We present a glass description of the mechanical anomalies found in torsion oscillator measurements. Our results show that it is not necessary to invoke a supersolid interpretation to explain these mechanical anomalies. Previously, we demonstrated that the back-action of a glassy subsystem present in solid ⁴He can account for frequency change and dissipation peak in single torsion oscillator experiments. Here, we show that the same glassy back-action can explain the experimental results of the composite torsion oscillator developed by the Rutgers group, which measures the response of solid ⁴He at the in-phase mode f ₁=496 Hz and out-of-phase mode f ₂=1173 Hz.