posted on 2024-01-10, 21:31authored byMuhammad Akram, Jesse Kapeghian, Jyotirish Das, Roser Valentí, Antia S. Botana, Onur Erten
Motivated
by the recent developments in moiré superlattices
of van der Waals magnets and the desire to control the magnetic interactions
of α-RuCl3, here we present a comprehensive theory
of the long-range ordered magnetic phases of twisted bilayer α-RuCl3. Using a combination of first-principles calculations and
atomistic simulations, we show that the stacking-dependent interlayer
exchange gives rise to an array of magnetic phases that can be realized
by controlling the twist angle. In particular, we discover a complex
hexagonal domain structure in which multiple zigzag orders coexist.
This multidomain order minimizes the interlayer energy while enduring
the energy cost due to domain wall formation. Further, we show that
quantum fluctuations can be enhanced across the phase transitions.
Our results indicate that magnetic frustration due to stacking-dependent
interlayer exchange in moiré superlattices can be exploited
to tune quantum fluctuations and the magnetic ground state of α-RuCl3.