Piezoelectric-based uniaxial strain cell with high strain throughput and homogeneity

Abstract

We seek for novel electronic phenomena by using external strain engineering, namely, by the application of external uniaxial strain. A piezoelectric-based uniaxial strain cell has been recently developed by Hicks et al. and successfully utilized for studies of various unconventional superconductors. Here, we propose a modified design that minimizes effects originating from the asymmetry of the strain cell design, in particular with minimal bending moments, by placing the sample at the axis of mirror symmetry of the device to balance out the reactive forces. Results of finite element analyses indicate that placing the sample offset to the axis of the mirror symmetry indeed causes an increase of strain inhomogeneity up to 10%, both at room temperature and at 4.2 K. Furthermore, we found that this bending reduces the overall achievable strain down to 30% of its maximal value without the bending. We also experimentally demonstrate the potential of our constructed device by tracking the displacement of the anvils of the strain cell with a parallel plate capacitor. The full range of motion of the piezo-stacks were demonstrated at room temperature. With a sample and at 0.9 K, we achieved a uniaxial strain of −1.5%, which is enough to induce electronic change in typical materials.

Uniaxial-strain control of nematic superconductivity in SrxBi2Se3

“…In this work, we measured the magnetoresistance of single-crystalline Sr 0.06 Bi 2 Se 3 samples (with the critical temperature T c of 2.8 K; see Supplementary Note 1) . The sample was affixed onto a custom-made uniaxial strain cell 31 , a modified version of the recent invention 32 , mounted inside a vector magnet. The sample was cut along one of the a axes (Bi-Bi bond direction), which we define as the x axis (Figs.…”

“…The effect of thermal contraction of the sample and the strain cell should be taken into consideration. Because the materials used in the strain cell are placed symmetrically between the compressive and tensile arms, the thermal strain on the sample originates only from the asymmetric part 31 ; on the compressive arm, the sample with the length L sample of 1.14 mm is placed, but on the tensile arms there are Ti blocks. This 1.14-mm length Ti part shrinks less than the sample, resulting in a tensile strain to the sample after cooling down from the epoxy curing temperature (around 350 K).…”

“…We constructed a custom-made piezoelectric-based uniaxial strain cell (ref. 31 ), based on the design of ref. 32 .…”

“…Thus, the thermally-induced strain to the sample is tensile and (Δ L Ti − Δ L sample )/ L sample = +0.13% considering L Ti = L Sample . In addition, because of the stiffness of the component materials, in particular the epoxy, the actual strain transmitted to the sample may be reduced by roughly 56% 31 . Thus, the value +0.13% should be considered as the upper bound, and the lower bound should be 0.13% × 0.56 = 0.07%.…”

Controlling superconductivity of CeIrIn$_5$ microstructures by substrate selection

“…In bulk crystals, however, strain and strain gradients are usually weak. When it is desirable to purposely induce strain, often an elaborate straining apparatus is required 5,6 .…”