Research Highlights
Resonating valence bond spin liquid induced by kinetic energy frustration
In the early '70s Anderson and Fazekas proposed an intriguing new phase of matter, where electrons pair up into resonating singlets and remain fluctuating down to the lowest temperatures, forming a resonating valence bond (RVB) quantum spin liquid (QSL) -- in stark contrast with the more conventional Neel antiferromagnetic order. This idea seeded a new area of research that has become a major component of modern condensed matter physics and led to seminal discoveries of new behaviour encompassing emergent symmetries, fractionalisation, and topological order.
Despite extensive efforts over the past fifty years, Anderson’s original proposal has hitherto evaded experimental discovery. For decades scientists have focused on attaining a quantum spin liquid phase by tailoring the interactions between the electrons. In our work, we change paradigm and look for avenues to induce quantum spin liquid behaviour by tailoring the kinetic energy of the electrons.
Using a combination of analytics and numerics we show that lightly doping Mott insulators on lattices of corner-sharing tetrahedra stabilises a remarkably-exact short-ranged RVB spin liquid -- a consequence of so-called kinetic frustration. This phase harbours spin-charge separation and bosonic holon excitations. The close-to-realistic (infinite-U Hubbard) Hamiltonian holds great promise for experimental verification.
In addition to addressing the long-standing puzzle of stabilising a short-ranged RVB quantum spin liquid phase in a realistic Hamiltonian, our work also puts forward a potential paradigm shift in the physics mechanisms that can give rise to quantum spin liquid behaviour: from frustrated spin interactions to kinetic energy frustration.
A resonant valence bond spin liquid in the dilute limit of doped frustrated Mott insulators, Cecilie Glittum, Antonio Štrkalj, Dharmalingam Prabhakaran, Paul A. Goddard, Cristian D. Batista, Claudio Castelnovo, Nature Physics (2025).