Local optical control of ferromagnetism and chemical potential in a topological insulator

Abstract

Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb)${}_2$Te${}_3$ grown on SrTiO${}_3$. By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO${}_3$ substrates, we control the local chemical potential of the films. This optical gating effect allows us to write and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. Dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.

15 pages, 5 figures

References in corpus (12)

• Non-Abelian Anyons and Topological Quantum Computation
• Experimental Observation of the Quantum Anomalous Hall Effect in a Magnetic Topological Insulator
• Topological Field Theory of Time-Reversal Invariant Insulators
• Quantized Anomalous Hall Effect in Magnetic Topological Insulators
• Topological Surface States Protected From Backscattering by Chiral Spin Texture
• All-optical control of ferromagnetic thin films and nanostructures
• Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3
• Giant Anisotropic Magnetoresistance in a Quantum Anomalous Hall Insulator
• Quantized chiral edge conduction on reconfigurable domain walls of a magnetic topological insulator
• Large discrete jumps observed in the transition between Chern states in a ferromagnetic Topological Insulator
• Chiral transport along magnetic domain walls in the quantum anomalous Hall effect
• Characterizing the Structure of Topological Insulator Thin Films

Cited by in corpus (9)

• Tailoring tricolor structure of magnetic topological insulator for robust axion insulator
• Quantized chiral edge conduction on reconfigurable domain walls of a magnetic topological insulator
• Observation of superparamagnetism in coexistence with quantum anomalous Hall C=$\pm$1 and C=0 Chern states
• Noncollinear twisted RKKY interaction on the optically driven SnTe(001) surface
• Confinement and Fermion Doubling Problem in Dirac-like Hamiltonians
• Optical control of topological memory based on orbital magnetization
• Vector Chirality $\kappa$ Driven Topological Phase Transition and the Associated Anomalous Hall Conductivity Tuning in a Non-Collinear Antiferromagnet
• Fresnel diffraction imaging of surface nanostructure using coherent resonant X-ray scattering
• Non-local Chemical Potential Modulation in Topological Insulators Via Electric Field Driven Trapped Charge Migration