Unaffected nonclassical response of solid (4)He under elastic modulus variation

Abstract

The superflow in solid helium was detected by a decrease in the resonant period of a torsional oscillator (TO) below 0.2 K. Recently, the shear modulus of solid helium has shown an unusual increase with a striking resemblance to those of the TO anomaly. The similarities have invigorated alternative nonsuperfluid explanations for the decrease in the period. Here, we report the influence of the shear modulus change on the resonant period of the TO to examine the fundamental connection between the two phenomena. The period of TO that exhibits quantitatively different drive dependence is not susceptible to the elastic modulus change, indicating that the microscopic origin of the TO anomaly is different from the shear modulus change.