Quantum strontium titanate shows no superconductivity near absolute zero

Researchers at the University of Cincinnati have created a strontium titanate (SrTiO3) platform achieving electron mobility up to 7400 in two-dimensional electron gases. Despite systematically exploring electron densities expected to induce superconductivity, the team observed no superconducting transition even when cooling the material to approximately 10 mK, a temperature incredibly close to absolute zero. This suggests that vertical confinement and electronic orbital rearrangement may suppress superconductivity in high mobility SrTiO3 systems, while the fabrication technique offers a promising path toward new quantum devices. Commercial strontium titanate (SrTiO3) single crystals served as the foundation for fabricating two-dimensional electron gases (2DEGs) using a cost-effective hydrogen plasma exposure technique, eliminating the need for complex thin film growth processes. This fabrication method proved compatible with electron-beam lithography patterning at the few-micron scale, suggesting potential for further down-scaling towards mesoscopic and quantum device sizes. Device channel widths varied from 5 to 40 micrometers, alongside channel-gate gaps of 5, 20, and 80 micrometers, allowing for systematic exploration of device geometry effects. Researchers fabricated and tested devices labeled A through H, documenting the measured Hall density…