arXiv subjects

Gastón Blatter

Publications and source records attributed to Gastón Blatter.

3 recordsLinked to original sources

arXiv2026

Surface-bulk hybridization enhances the Berry curvature dipole in GaAs(110)

Symmetry breaking at crystalline boundaries can enable electronic responses that are forbidden in the bulk. Here, we investigate the Berry curvature dipole (BCD) at GaAs(110) surfaces using first-principles calculations. While the BCD vanishes in bulk GaAs due to symmetry constraints, the reduced surface symmetry permits a finite dipole. We show that surface relaxation promotes hybridization between bulk and surface states, which strongly influences the surface BCD. Specifically, in unrelaxed slabs, the BCD arises predominantly from interband coupling among exponentially localized surface states lying within the projected bulk band gap. Surface relaxation shifts these states into the energy range of the bulk continuum, transforming them into surface resonances and promoting hybridization with bulk-like states. This hybridization generates pronounced Berry-curvature hot spots, resulting in an overall enhancement of the BCD. Our results highlight the importance of surface relaxation for accurately describing surface--bulk hybridization, which in turn plays a key role in Berry-curvature-driven responses at crystalline boundaries.

cond-mat.mtrl-sci↗

arXiv2026

Sign control of photocurrents by spin-group-symmetry breaking in altermagnetic insulators

Controlling physical responses through symmetry breaking is a central paradigm in quantum materials, enabling novel functionalities. Here we determine the effects of spin-group-symmetry breaking on nonlinear optical responses of collinear altermagnetic insulators. Using shear strain as an example, we show that the direction of symmetry-breaking induced components of charge and spin photocurrents are locked to the sign of the strain. In the absence of spin-orbit coupling, this effect is intuitively captured by the spin-gap asymmetry--an imbalance between spin-up and spin-down direct band gaps which couples trilinearly with the Néel order and the strain. We demonstrate this mechanism with density functional theory calculations on the recently proposed altermagnet CuWP$_2$S$_6$. Having symmetry-guided control of both charge and spin photocurrents allows, vice versa, to reveal and investigate altermagnetism in insulating materials by exploration of their optical responses.

cond-mat.mes-hall↗

arXiv2023

Tuning vortex critical velocity in Mo$_2$N thin films via striped magnetic domain configuration

We report on the impact of the magnetic domain stripe configuration on the critical velocity of vortices in superconducting/ferromagnetic bilayers. Using a 23 nm thick Mo$_2$N film, covered by a 48 nm FePt layer with tunable nanosized striped domains, we demonstrate that flux instability at low magnetic fields depends on the orientation of the stripes. When the stripes are perpendicular to the applied current and act as vortex guides, the velocity values reach 5 km/s, duplicating those found when configured parallel to the current, creating winding vortex paths. Our results indicate that vortex critical velocities can be tuned by configuring different domain structures, providing a platform to understand vortex dynamics in superconducting microstrips.

cond-mat.supr-con↗