Evidence for topological contribution to spin shift current in antiferromagnetic Ti[Formula: see text]C[Formula: see...

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Chemistry

Background:

• Shift current, a non-linear photocurrent, is linked to quantum geometry.
• Topological origins of shift photocurrent in non-centrosymmetric systems are a recent focus.
• A reverting Thouless pump (RTP) is associated with topological classification beyond the standard tenfold paradigm.

Purpose of the Study:

• To perform a first-principles computational analysis of antiferromagnetic Ti2C2 MXene monolayers.
• To investigate the topological properties and shift current generation in this material.
• To explore the role of magnetic ordering and its impact on topological invariants.

Main Methods:

• First-principles computational analysis.
• Density Functional Theory (DFT) calculations.
• Analysis of spin-resolved electronic band structure and topological invariants.

Main Results:

• Evidence of a perturbed reverting Thouless pump (RTP) in each spin sector was found, breaking quantization.
• A giant spin-resolved shift current was observed despite the perturbation of the RTP.
• The system was classified as a fragile topological insulator with coupled trivial bands, and mid-gap edge states were identified.

Conclusions:

• Magnetic ordering in Ti2C2 MXenes breaks inversion symmetry, leading to complex topological phenomena.
• The persistence of a large spin-resolved shift current highlights its robustness even with a perturbed RTP.
• The material exhibits fragile topological insulator characteristics, offering potential for novel electronic and spintronic applications.