Solids of quantum Hall skyrmions in graphene

Autor: Kenji Watanabe, Andrea Young, Haoxin Zhou, Hryhoriy Polshyn, T. Taniguchi
Rok vydání: 2019
Předmět:
Zdroj: Nature Physics. 16:154-158
ISSN: 1745-2481
1745-2473
Popis: Partially filled Landau levels host competing electronic orders. For example, electron solids may prevail close to integer filling of the Landau levels before giving way to fractional quantum Hall liquids at higher carrier density1,2. Here, we report the observation of an electron solid with non-collinear spin texture in monolayer graphene, consistent with solidification of skyrmions3—topological spin textures characterized by quantized electrical charge4,5. We probe the spin texture of the solids using a modified Corbino geometry that allows ferromagnetic magnons to be launched and detected6,7. We find that magnon transport is highly efficient when one Landau level is filled ($$\nu =1$$), consistent with quantum Hall ferromagnetic spin polarization. However, even minimal doping immediately quenches the magnon signal while leaving the vanishing low-temperature charge conductivity unchanged. Our results can be understood by the formation of a solid of charged skyrmions near $$\nu =1$$, whose non-collinear spin texture leads to rapid magnon decay. Data near fractional fillings show evidence of several fractional skyrmion solids, suggesting that graphene hosts a highly tunable landscape of coupled spin and charge orders. The authors use spin waves to demonstrate that charged quantum Hall skyrmions exist away from integer filling. They also see evidence of several fractional skyrmion states.
Databáze: OpenAIRE
Externí odkaz: