Author(s)

Nobuo Suzuki^1*, Fumitaka Matsubara², Sumiyoshi Fujiki¹, Takayuki Shirakura³

¹Faculty of Science and Technology, Tohoku Bunka Gakuen University, Sendai, Japan.
²Department of Applied Physics, Tohoku University, Sendai, Japan.
³Faculty of Humanities and Social Sciences, Iwate University, Morioka, Japan.

We study the ground state of an S=1/2 anisotropic a (≡J_z/J_xy) Heisenberg antiferromagnet with nearest (J₁) and next-nearest (J₂) neighbor exchange interactions on a triangular lattice using the exact diagonalization method. We obtain the energy, squared sublattice magnetizations, and their Binder ratios on finite lattices with N≤36 sites. We estimate the threshold J^(t) ₂ (a) between the three-sublattice Néel state and the spin liquid (SL) state, and J^(s) ₂ (a)  between the stripe state and the SL state. The SL state exists over a wide range in the α-J₂ plane. For α>1 , the xy component of the magnetization is destroyed by quantum fluctuations, and the classical distorted 120° structure is replaced by the collinear state.

Quantum Spin, Triangular Lattice, Quantum Fluctuation, Spin Liquid, Exact Diagnalization

Suzuki, N. , Matsubara, F. , Fujiki, S. and Shirakura, T. (2019) Phase Diagram of an S = 1/2 J₁-J₂ Anisotropic Heisenberg Antiferromagnet on a Triangular Lattice. Journal of Modern Physics, 10, 8-19. doi: 10.4236/jmp.2019.101002.