Dissipative Landau-Zener tunneling in the crossover regime from weak to strong environment coupling.

Landau-Zener tunneling, which describes the transition in a two-level system during a sweep through an anti-crossing, is a model applicable to a wide range of physical phenomena. Realistic quantum systems are affected by dissipation due to coupling to their environments. An important aspect of understanding such open quantum systems is the relative energy scales of the system itself and the system-environment coupling, which distinguishes the weak- and strong-coupling regimes.

Establishing Partnerships for Science Outreach Inside and Outside the Undergraduate Classroom.

STEM outreach experiences provide aspiring scientists and healthcare professionals with opportunities to grow into new roles, integrate knowledge, and acquire soft skills. While STEM outreach publications often describe the outreach performed, few focus on how to establish strong partnerships, which are essential for outreach endeavors to succeed. Information on this is more important than ever before-grant agencies commonly require education and outreach plans that will reach a broader audience.

Observation of Quantum Anomalous Hall Effect and Exchange Interaction in Topological Insulator/Antiferromagnet Heterostructure.

Integration of a quantum anomalous Hall insulator with a magnetically ordered material provides an additional degree of freedom through which the resulting exotic quantum states can be controlled. Here, an experimental observation is reported of the quantum anomalous Hall effect in a magnetically-doped topological insulator grown on the antiferromagnetic insulator Cr O . The exchange coupling between the two materials is investigated using field-cooling-dependent magnetometry and polarized neutron reflectometry.

Exchange-biasing topological charges by antiferromagnetism.

Geometric Hall effect is induced by the emergent gauge field experienced by the carriers adiabatically passing through certain real-space topological spin textures, which is a probe to non-trivial spin textures, such as magnetic skyrmions. We report experimental indications of spin-texture topological charges induced in heterostructures of a topological insulator (Bi,Sb)Te coupled to an antiferromagnet MnTe. Through a seeding effect, the pinned spins at the interface leads to a tunable modification of the averaged real-space topological charge.

Tailoring exchange couplings in magnetic topological-insulator/antiferromagnet heterostructures.

Magnetic topological insulators such as Cr-doped (Bi,Sb)Te provide a platform for the realization of versatile time-reversal symmetry-breaking physics. By constructing heterostructures exhibiting Néel order in an antiferromagnetic CrSb and ferromagnetic order in Cr-doped (Bi,Sb)Te, we realize emergent interfacial magnetic phenomena which can be tailored through artificial structural engineering. Through deliberate geometrical design of heterostructures and superlattices, we demonstrate the use of antiferromagnetic exchange coupling in manipulating the magnetic properties of magnetic topological insulators.