Chiral spin liquid with spinon Fermi surfaces in the spin-$$\frac{1}{2}$$ triangular Heisenberg model

Journal Article · 15 December 2019 · Physical Review. B

DOI: https://doi.org/10.1103/physrevb.100.241111 · OSTI ID:1800369

Gong, Shou-Shu  ^[1]; Zheng, Wayne ^[2]; Lee, Mac ^[3]; Lu, Yuan-Ming ^[2]; Sheng, D. N. ^[4]

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1. Beihang University, Beijing (China); OSTI
2. The Ohio State Univ., Columbus, OH (United States)
3. California State Univ., Northridge, CA (United States); Univ. of California, San Diego, CA (United States)
4. California State Univ., Northridge, CA (United States)

Here, we study the interplay of competing interactions in spin-$$\frac{1}{2}$$ triangular Heisenberg model through tuning the first- ($$J_1$$), second- ($$J_2$$), and third-neighbor ($$J_ 3$$) couplings. Based on a large-scale density-matrix renormalization group calculation, we identify a quantum phase diagram of the system and discover a gapless chiral spin-liquid (CSL) phase in the intermediate $$J_2$$ and $$J_ 3$$ regime. This CSL state spontaneously breaks time-reversal symmetry with finite scalar chiral order, and it has gapless excitations implied by a vanishing spin triplet gap and a finite central charge on the cylinder. Moreover, the central charge grows rapidly with the cylinder circumference, indicating emergent spinon Fermi surfaces. To understand the numerical results we propose a parton mean-field spin-liquid state, the U(1) staggered flux state, which breaks time-reversal symmetry with chiral edge modes by adding a Chern insulator mass to Dirac spinons in the U(1) Dirac spin liquid. This state also breaks lattice rotational symmetries and possesses two spinon Fermi surfaces driven by nonzero $$J_2$$ and $$J_3$$, which naturally explains the numerical results. This realizes an example of a gapless CSL state with coexisting spinon Fermi surfaces and chiral edge states, demonstrating the rich family of interesting quantum phases emergent from competing interactions in triangular-lattice magnets.

• Research Organization: California State Univ. (CalState), Long Beach, CA (United States)
• Sponsoring Organization: Fundamental Research Funds for the Central Universities; National Natural Science Foundation of China (NSFC); National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: FG02-06ER46305
• OSTI ID: 1800369
• Journal Information: Physical Review. B, Journal Name: Physical Review. B Journal Issue: 24 Vol. 100; ISSN 2469-9950
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English