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Spin Waves and Stability of Magnetic Order in Frustrated Magnets

1992; Institute of Physics; Volume: 17; Issue: 5 Linguagem: Inglês

10.1209/0295-5075/17/5/014

1286-4854

Christoph Bruder, Frédéric Mila,

Quantum and electron transport phenomena

We study the quantum renormalization of the spin-wave spectrum and of the magnetization in the 2d antiferromagnetic J1-J2 model in the large-S limit. We compare linear spin-wave, first-order spin-wave and Schwinger boson mean-field theories and show that the last two agree to order 1/S for any J2/J1, whereas linear spin-wave theory becomes qualitatively wrong in the region of strong frustration (J2/J1 ≈ 1/2). The main consequence, namely the possibility of stabilizing long-range order by quantum fluctuations, is emphasized in a related example, the ferromagnetic J1-J2-J3 model. The compatibility of these results with numerical studies of the S = 1/2 case is discussed.