Thermodynamics of the Spin Luttinger Liquid in a Model Ladder Material

Ch. Rüegg (1) , K. Kiefer (2) , B. Thielemann (3) , D. F. Mcmorrow (1) , V. Zapf (4) , Bernard Normand (5) , M. B. Zvonarev (6) , P. Bouillot (6) , C. Kollath (7) , T. Giamarchi (6) , Sylvain Capponi (8, 9) , Didier Poilblanc (8, 9) , D. Biner (10) , K. W. Krämer (10)

1 London Centre for Nanotechnology
2 BENSC - Berlin Neutron Scattering Center
3 Laboratory for neutron scattering
4 NHMFL - National High Magnetic Field Laboratory
5 UNIL - Université de Lausanne = University of Lausanne
6 DPMC-MaNEP - DPMC
7 CPHT - Centre de Physique Théorique [Palaiseau]
8 FFC - Fermions Fortement Corrélés (LPT)
9 LPT - Laboratoire de Physique Théorique
10 Department of Chemistry and Biochemistry

The phase diagram in temperature and magnetic field of the metal-organic, two-leg spin-ladder compound (C5H12N)2CuBr4 is studied by measurements of the specific heat and the magnetocaloric effect. We demonstrate the presence of an extended spin Luttinger-liquid phase between two field-induced quantum critical points, which exists over a broad range of temperature. Based on an ideal spin-ladder Hamiltonian, comprehensive numerical modelling of the ladder specific heat is presented across its complete phase diagram. It is found to be in excellent quantitative agreement with the experimental data.

Domaines: Autre [cond-mat.other]

Ch. Rüegg, K. Kiefer, B. Thielemann, D. F. Mcmorrow, V. Zapf, et al.. Thermodynamics of the Spin Luttinger Liquid in a Model Ladder Material. Physical Review Letters, 2008, 101, pp.247202. ⟨10.1103/PhysRevLett.101.247202⟩. ⟨hal-00316069⟩