Angel Rubio
The experimental realization of atomically thin layers of magnetic van der Waals (vdW) materials has sparked a new interest in two-dimensional magnetism. In particular, and due to the presence of strong anisotropy, quantum fluctuations, and spin-orbit e ects, these materials are prime candidates to host exotic and topological phenomena of interest for future spintronics and quantum computation devices. They are also sensitive to a wide range of material engineering techniques, allowing their electronic and magnetic state to be tuned with high precision. Although recent progress has demonstrated that optical engineering techniques can be used realize exotic non-equilibrium states, driving a system with lasers is often associated with excessive heating. A path to circumvent this problem is to instead embed the system in an optical cavity, where the effective light-matter coupling can be enhanced via photon mode volume compression. Here, we identify a nearly ideal material platform to explore cavity quantum electrodynamics (c-QED) engineering by extending c-QED into the magnetic regime of two-dimensional heterostructures. Speci cally, we demonstrate how an optical cavity can be used to control the magnetic ground state of the proximate quantum spin liquid -RuCl3. Depending on the cavity frequency, photon occupation, and the strength of the e ective light-matter coupling, we nd that it is possible to transform the equilibrium zigzag antiferromagnetic order into any of the magnetic phases supported by the extended Kitaev model. As our key result we nd that for frequencies of a few THz and for moderate light-matter couplings, the interaction between the magnetic system and the vacuum uctuations of the cavity is su fficient to transform -RuCl3 from a zigzag antiferromagnet to a ferromagnet. This constitute a realistic proposal of where the magnetic order of a material system is controlled solely by vacuum fluctuations. In addition, we nd that by pumping the cavity to the few photon regime, it is possible to push the system into the antiferromagnetic Kitaev quantum spin liquid state.