Field-tunable quantum disordered ground state in the triangular-lattice antiferromagnet NaYbO₂

Area of Science:

• Condensed Matter Physics
• Quantum Magnetism
• Materials Science

Background:

• Frustrated quantum magnetism arises from competing magnetic interactions on lattices like the triangular lattice.
• Ideal experimental realizations of such systems are rare, hindering the study of exotic quantum states.
• Antiferromagnetically coupled S=1/2 spins are key to understanding quantum spin liquids.

Purpose of the Study:

• To investigate NaYbO2 as a potential realization of a quantum spin liquid on an ideal triangular lattice.
• To explore the magnetic properties and ground state of NaYbO2 under varying temperatures and magnetic fields.
• To understand the transition from a quantum disordered state to magnetic order.

Main Methods:

• Synthesis and characterization of NaYbO2.
• Low-temperature specific heat measurements down to 50 mK.
• Magnetic field dependent measurements to probe phase transitions.

Main Results:

• NaYbO2 exhibits an ideal triangular lattice of effective J_eff=1/2 moments without site disorder.
• No conventional magnetic order was observed down to 50 mK, suggesting a quantum spin liquid ground state.
• Specific heat data showed a two-peak structure and quadratic temperature dependence, consistent with a 2D Dirac spin liquid.
• Application of a magnetic field induced a transition to a collinear ordered state, matching theoretical predictions for an up-up-down structure.

Conclusions:

• NaYbO2 is a model system for studying quantum spin liquids due to its ideal structure and tunable properties.
• The compound demonstrates an intrinsically quantum disordered ground state, transitioning to order under magnetic fields.
• This material provides a versatile platform for exploring spin liquid physics with control over field and temperature.