Quantum physics talk - Reyes Calvo

Speaker: 
Reyes Calvo

Ikerbasque Research Associate Professor
Basque Center for Materials, Applications and Nanostructures (BCMaterials), Spain

Title: 
Strain-engineering quantum phenomena in 2D materials

Abstract:
Since the discovery of graphene, two-dimensional (2D) materials spanning semiconductors, superconductors and magnets have been isolated. A defining characteristic of these materials is their sensitivity to external perturbations, which makes them highly tunable. Strain engineering exploits their mechanical flexibility to modify electronic, optical and magnetic properties. While strain tuning of semiconducting properties has been extensively explored, its effects on quantum phenomena such as superconductivity and magnetism remain comparatively unexplored, despite theoretical predictions of substantial strain-induced changes and emergent phase transitions. This is partly due to the difficulty of applying controlled strain at the cryogenic temperatures where many of these phenomena emerge.

In this talk, I will present a series of experiments using thermal-expansion mismatch with polymeric substrates to induce uniform biaxial compressive strain in 2D crystals at cryogenic temperatures. Using this approach, we demonstrate strain tuning of neutral and charged excitons in monolayer transition-metal dichalcogenides [1], modulation of the superconducting transition in multilayer NbSe₂ [2], and enhanced magnetoresistance and magnetic anisotropy in the antiferromagnetic semiconductor CrSBr [3]. Together, these results establish thermal contraction mismatch with polymeric substrates as a simple and versatile approach for controlling electronic and magnetic phenomena in 2D materials at low temperatures, with potential applications in spintronics and quantum technologies.

References
[1] E. Henriquez-Guerra et al., “Large Biaxial Compressive Strain Tuning of Neutral and Charged Excitons in Single-Layer Transition Metal Dichalcogenides,” ACS Applied Materials & Interfaces 15, 57369–57378 (2023).

[2] E. Henriquez-Guerra et al., “Modulation of the Superconducting Phase Transition in Multilayer 2H-NbSe₂ Induced by Uniform Biaxial Compressive Strain,” Nano Letters 24, 10504–10509 (2024).

[3] E. Henriquez-Guerra et al., “Strain Engineering of Magnetoresistance and Magnetic Anisotropy in CrSBr,” Advanced Materials (2025), 2506695.