Vibration isolation from cooling reservoir is a critical problem for low temperature STM. Typically, the cooling is achieved by a soft linkage (copper braid) between the cooling source and the sample holder, to transfer the cooling power, and to avoid transferring much of the vibration and bubbling noise of the cooling source (see figures). In most STM structures, the residual vibration and bubbling noises from the cryostat which transfer through the copper braid from the cryostat will directly couple into the tunneling junction (top) This typically causes relative motion between sample and tip, degrading the performance of the STM.

In the “Walker” type scan head design (bottom), since the scanning head is standing directly on the sample holder, the vibrations and bubbling noises which transfer through the copper braid will not directly couple into the tunneling junction . In addition, due to its compact structure and high resonant frequency, the scan head rejects more external disturbances. Therefore one can easily achieve high resolution with a “Walker” type scan head.