Large response of charge stripes to uniaxial stress in ${\mathrm{La}}_{1.475}{\mathrm{Nd}}_{0.4}{\mathrm{Sr}}_{0.125}{\mathrm{CuO}}_4$

The La-based “214” cuprates host several symmetry-breaking phases, including superconductivity, charge and spin order in the form of stripes, and a structural orthorhombic-to-tetragonal phase transition. Therefore these materials are an ideal system to study the effects of uniaxial stress onto the various correlations that pervade the cuprate phase diagram. We report resonant x-ray scattering experiments on ${\text{La}}_{1.475}{\text{Nd}}_{0.4}{\text{Sr}}_{0.125}\text{Cu}{\text{O}}_4$(LNSCO-125) that reveal a significant response of charge stripes to uniaxial tensile stress of $\sim 0.1\mathrm{GPa}$. These effects include a reduction of the onset temperature of stripes by $\sim 50\mathrm{K}$, a 29-K reduction of the low-temperature orthorhombic-to-tetragonal transition, competition between charge order and superconductivity, and a preference for stripes to form along the direction of applied stress. Altogether, we observe a dramatic response of the electronic properties of LNSCO-125 to a modest amount of uniaxial stress.

Figure 1

(a) A diagram depicting the ${\mathrm{CuO}}_6$ octahedral tilts in both the LTO and LTT phases. In the LTO phase, neighboring octahedra tilt in opposite directions (clockwise and counterclockwise) along the [110] direction. In the LTT phase, adjacent ${\mathrm{CuO}}_2$ layers have orthogonal tilts along the [100] and [010] directions. (b) Temperature-dependent RXS scans of the CO peak in LNSCO-125 measured at the Cu $L_3$-edge ($E=931.5$ eV). The gray dashed line is a polynomial fit of the high-temperature background curve measured at 300 K. The complete set of temperature-dependent scans is presented in Fig. S2 [9]. (c) RXS scans in the LTO phase, which show a gradual temperature dependence. (d) Lorentzian fits of the background-subtracted curves shown in (c).

Figure 2

(a) An image of the titanium strain device and LNSCO-125 crystals. The stress sample is mounted in the center across a gap using a stiff epoxy, and the control sample is mounted on the titanium using silver paint [9]. (b) Temperature dependence of the (001) Bragg peaks measured at the apical O $K$-edge ($E=532.5$ eV) in both the stress and control samples corresponding to the LTT phase transition. The transition temperature is suppressed by 29 K with the applied stress.

Figure 3

(a) Temperature dependence of the CO peaks in the stress and control samples. The solid lines serve as guides to the eye. The dashed lines correspond to the LTT transition temperatures determined from Fig. 2. The inset shows a diagram of the stress sample, where we label $a$ (blue) and $b$ (orange) as the directions parallel to and perpendicular to the direction of applied stress, respectively. Measurements of the stress sample along the $a$ direction were performed at two different facilities: measurements from the Canadian Light Source are triangles and measurements from BESSY-II are circles [9]. (b) Comparison of RXS scans of the stress sample along the $a$ and $b$ directions near the LTT transition. The gray dashed line is a polynomial fit of the high-temperature background curve measured at 150 K. The onset of the charge stripes along the direction of applied stress precedes that of the perpendicular direction by approximately $6\mathrm{K}$.