Regensburg 1998 – scientific programme

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DY: Dynamik und Statistische Physik

DY 44: Spinmodelle

DY 44.1: Talk

Thursday, March 26, 1998, 10:30–10:45, H3

Plateaux in Magnetization Curves of Antiferromagnetic Heisenberg Spin-1/2 Ladders — •A. Honecker¹, D.C. Cabra², and P. Pujol¹ — ¹SISSA, Via Beirut 2-4, 34014 Trieste, Italy — ²Departamento de Física, Universidad Nacional de la Plata, C.C. 67, (1900) La Plata, Argentina

Magnetization processes of N coupled spin-1/2 Heisenberg chains (so-called ‘ladders’) are studied using numerical diagonalization of finite systems, series expansions and a bosonization approach. In the strong-coupling limit the magnetization can take on only N+1 different rational fractions of the saturation value. We find that the magnetization generically exhibits plateaux as a function of the applied field at precisely the same rational fractions that appear in the strong coupling limit. Our main focus are ladders with 3 legs where plateaux with magnetization one third of the saturation value are shown to exist.

[1] D.C. Cabra, A. Honecker, P. Pujol, preprint cond-mat/9707090, to appear in Phys. Rev. Lett.