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TT: Fachverband Tiefe Temperaturen

TT 12: Correlated Electrons: Frustrated Magnets - General 1

TT 12.9: Hauptvortrag

Montag, 20. März 2017, 17:15–17:45, HSZ 03

U(1) Quantum Spin Liquid Ground State in the Triangular Antiferromagnet YbMgGaO₄ — •Yuesheng Li — Experimental Physics VI, Center for Electronic Correlations and Magnetism, University of Augsburg

Quantum spin liquids are novel phases of matter, where spins are entangled up to long-distances and times without symmetry breaking even at 0 K due to the strong quantum fluctuations. And the candidate materials were actively sought after. However, most of the existing candidates suffer from magnetic defect, lattice distortion, antisymmetric exchange (Dzyaloshinskii-Moriya interactions) and (or) interlayer magnetic coupling. Recently, a new structurally perfect triangular antiferromagnet YbMgGaO₄ was reported by our group [1,2]. The aforementioned structural shortcomings are avoided [1]. (1) No spin symmetry breaking is detected down to 0.048 K [1,3], and the spin entropy is precisely measured to be almost zero at 0.06 K [1]. (2) The measured magnetic heat capacity behaves as C_m ∼ T^2/3 down to 0.06 K under 0 T [1]. (3) The muon spin relaxation rates exhibit temperature-independent plateaus below 0.4 K [3]. (1)-(3) suggest YbMgGaO₄ may be the first experimental realization of the U(1) quantum spin liquid ground state.

[1] Yuesheng Li et al., Sci. Rep. 5, 16419 (2015)

[2] Yuesheng Li et al., Phys. Rev. Lett. 115, 167203 (2015)

[3] Yuesheng Li et al., Phys. Rev. Lett. 117, 097201 (2016)