title: Attractive Tomonaga-Luttinger liquid in a quantum spin ladder.
abstract: We present NMR measurements of a strong-leg spin-1/2 Heisenberg antiferromagnetic ladder compound (C7H10N)2CuBr4 under magnetic fields up to 15 T in the temperature range from 1.2 K down to 50 mK. From the splitting of NMR lines, we determine the phase boundary and the order parameter of the low-temperature (three-dimensional) long-range-ordered phase. In the Tomonaga-Luttinger regime above the ordered phase, NMR relaxation reflects characteristic power-law decay of spin correlation functions as 1/T1∝T(1/2K-1), which allows us to determine the interaction parameter K as a function of field. We find that field-dependent K varies within the 1<K<2 range, which signifies attractive interaction between the spinless fermions in the Tomonaga-Luttinger liquid.
authors.affiliation: Laboratoire National des Champs Magnétique Intenses, LNCMI-CNRS (UPR3228), UJF, UPS, and INSA, Boîte Postale 166, 38042, Grenoble Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Jeong
authors.affiliation: Laboratoire National des Champs Magnétique Intenses, LNCMI-CNRS (UPR3228), UJF, UPS, and INSA, Boîte Postale 166, 38042, Grenoble Cedex 9, France.
authors.forename: H
authors.initials: H
authors.lastname: Mayaffre
authors.affiliation: Laboratoire National des Champs Magnétique Intenses, LNCMI-CNRS (UPR3228), UJF, UPS, and INSA, Boîte Postale 166, 38042, Grenoble Cedex 9, France.
authors.forename: C
authors.initials: C
authors.lastname: Berthier
authors.affiliation: Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Schmidiger
authors.affiliation: Neutron Scattering and Magnetism, Laboratory for Solid State Physics, ETH Zurich, Zurich 8093, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Zheludev
authors.affiliation: Laboratoire National des Champs Magnétique Intenses, LNCMI-CNRS (UPR3228), UJF, UPS, and INSA, Boîte Postale 166, 38042, Grenoble Cedex 9, France.
authors.forename: M
authors.initials: M
authors.lastname: Horvatić