Department of Physics, University of Alberta, Edmonton, Alberta T6G 2G7, Canada.
Phys Rev Lett. 2010 May 14;104(19):195301. doi: 10.1103/PhysRevLett.104.195301. Epub 2010 May 10.
Torsional oscillator experiments on solid 4He show frequency changes which suggest mass decoupling, but the onset is broad and is accompanied by a dissipation peak. We have measured the elastic shear modulus over a broad frequency range, from 0.5 Hz to 8 kHz, and observe similar behavior-stiffening and a dissipation peak. These features are associated with a dynamical crossover in a thermally activated relaxation process in a disordered system rather than a true phase transition. If there is a transition to a dc response, e.g., to a supersolid state, it must occur below 55 mK.
固态 4He 的扭转振荡器实验显示出频率变化，这表明质量解耦，但起始很宽，并伴随着耗散峰。我们已经在很宽的频率范围内（从 0.5 Hz 到 8 kHz）测量了弹性剪切模量，并观察到类似的行为——变硬和耗散峰。这些特征与无序系统中热激活弛豫过程的动力学交叉有关，而不是真正的相变。如果存在向直流响应的转变，例如向超流态的转变，那么它必须在 55 mK 以下发生。
