Dominant Kitaev interaction and field-induced quantum phase transitions in triangular-lattice KCeSe2

TL;DR

This study reveals dominant Kitaev and Heisenberg interactions in KCeSe2, a triangular-lattice antiferromagnet, and demonstrates field-induced quantum phase transitions, establishing it as a platform for exploring quantum spin liquids beyond honeycomb lattices.

Contribution

The paper provides the first detailed experimental and theoretical analysis of Kitaev physics on a triangular lattice in KCeSe2, including identification of dominant interactions and quantum phase transitions.

Findings

Strong magnetic anisotropy indicating Kitaev physics

Identification of dominant ferromagnetic Kitaev and antiferromagnetic Heisenberg interactions

Observation of field-induced quantum phase transitions at 1.67 T and 3.8 T

Abstract

Realizing Kitaev interactions on triangular lattices offers a compelling platform for exploring quantum-spin-liquid physics beyond the conventional honeycomb lattice framework. Here, we investigate the triangular-lattice antiferromagnet KCeSe2, where multiple probes reveal strong magnetic anisotropy suggesting significant Kitaev physics. Through detailed and combined analysis of magnetization, neutron scattering, and thermodynamic experiments, we identify dominant ferromagnetic Kitaev ($K = -1.82$ K) and antiferromagnetic Heisenberg ($J = 1.34$ K) interactions that stabilize a stripe-$yz$ ordered ground state via an order-by-disorder mechanism. Magnetic fields applied along the Kitaev bond direction induce two phase transitions at 1.67 T and 3.8 T, consistent with density matrix renormalization group (DMRG) calculations predictions of a progression from stripe-$yz$ to stripe-canted and spin-polarized phases. Near the 1.67 T quantum critical point, enhanced quantum fluctuations suggest conditions favorable for exotic excitations. These results establish KCeSe2 as a platform for exploring Kitaev physics on triangular lattices.