Structural Phase Separation and Enhanced Superconductivity in La_1.875Ba_0.125CuO₄ Under Uniaxial Strain

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Materials

Background:

• Strain engineering is a key method for tuning quantum material properties.
• Lanthanum barium copper oxide (La$_{2-x}$Ba$_x$CuO$_4$ or LBCO) is a material exhibiting complex phase behavior near stripe instability.

Purpose of the Study:

• To investigate the impact of uniaxial compressive strain on the low-temperature phase of LBCO single crystals.
• To understand how induced structural phase separation affects superconductivity in LBCO.

Main Methods:

• Application of moderate uniaxial compressive strain to LBCO single crystals.
• Analysis of structural phase separation into low-temperature tetragonal (LTT), low-temperature less orthorhombic (LTLO), and plastically deformed nano-domain structures (PDNS).
• Measurement of superconducting transition temperatures for each induced structure.

Main Results:

• Strain suppresses the LTT phase volume fraction, increasing and broadening its superconducting transition temperature.
• The LTLO structure shows a sharp superconducting transition above 32 K, reaching ~36 K under maximum strain.
• The PDNS phase exhibits a broad superconducting transition that persists even after strain removal.

Conclusions:

• Structural phase separation in LBCO is highly sensitive to applied strain.
• Superconductivity in LBCO is intricately linked to its structural phases, particularly near stripe instability.
• Strain engineering offers a pathway to manipulate the superconducting behavior of LBCO.