Itinerant magnetism in moiré heterobilayer*

We study the two-dimensional electron gas in an external moiré potential using quantum Monte Carlo (QMC) methods. This continuum model is believed to describe the low-energy electrons in certain transition metal dichalcogenide (TMD) heterobilayers such as WSe₂/MoSe₂ and WSe₂/WS₂ [1,2]. Using auxiliary-field quantum Monte Carlo (AFQMC), and diffusion Monte Carlo (DMC), we find significant modifications to the Hartree-Fock (HF) magnetic phase diagram. These include a larger stability region of the paramagnetic phase at small interaction and a closer competition between the dominant antiferromagnetic phase with the incipient ferromagnetic phase at large interaction. We characterize an itinerant magnetic state, which has noncollinear magnetic order.

[1] N.C. Hu et al., PRB 104, 214403 (2021).

[2] Y. Zhang et al., arXiv:2005.04238.