Spectral and Thermodynamic Properties of a Strong-Leg Quantum Spin Ladder

Abstract

The strong-leg S=1/2 Heisenberg spin ladder system (C(7)H(10)N)(2)CuBr(4) is investigated using density matrix renormalization group calculations, inelastic neutron scattering, and bulk magnetothermodynamic measurements. Measurements showed qualitative differences compared to the strong-rung case. A long-lived two-triplon bound state is confirmed to persist across most of the Brillouin zone in a zero field. In applied fields, in the Tomonaga-Luttinger spin-liquid phase, elementary excitations are attractive, rather than repulsive. In the presence of weak interladder interactions, the strong-leg system is considerably more prone to three-dimensional ordering.

Incommensurate dynamic correlations in the quasi-two-dimensional spin liquid BiCu2PO6

“…Below 30 K the damping is consistent with an exponential activated behaviour Γ α = g α ∆ α /T exp (∆ α /T ), valid for gapped one-dimensional systems. 44 The fitted scale factors were g 1 = 1.05(1) and g 2 = 2.22 (16) for the low and high energy modes respectively and the fits are shown as solid and dashed lines in Fig. 4(c).…”

“…The rung coupling confines spinons into S=1 magnons and the low energy dynamic susceptibility exhibits a well defined, triply degenerate, single particle peak. 9 Theoretical understanding of the properties of even-leg ladders is highly developed [9][10][11] and a number of experimental realizations have allowed for a detailed understanding of the very rich physical phenomena present in spin-ladders for both the strong rung coupling (rung-singlet) [12][13][14] and strong-leg coupling (Haldane) 15,16 regimes. However, the physics of spin ladders with additional frustrating NNN interactions is not understood well.…”

ESR study of the spin ladder with uniform Dzyaloshinskii-Moriya interaction

“…7 Recently found organometallic compound (C 7 H 10 N 2 ) 2 CuBr 4 , abbreviated DIMPY for short, is an example of the strong-leg ladder with very weak anisotropic interactions. [8][9][10][11] Presence of the energy gap in the excitation spectrum was revealed by magnetic susceptibility 8 , specific heat 9 and magnetization 11,12 bulk measurements as well as by inelastic neutron scattering. 9,10 The energy gap was found 9 to be 0.33 meV, it can be closed by the magnetic field µ o H c1 = 3.0 T, while the saturation field is much higher 12 µ 0 H sat ≈ 30 T. The values of the exchange constants were determined from the DMRG fit of the measured inelastic neutron scattering spectra 11 and were found to be J leg = 1.42 meV and J rung = 0.82 meV.…”

Crystals for neutron scattering studies of quantum magnetism

“…Even without background subtraction and further analysis, one notices an additition sharp excitation branch. Theoretical and numerical studies allowed us to identify this mode with a novel two-magnon bound state [45]. A more thorough data reduction and new experiments in high magnetic fields are underway, fully justifying the effort and expense of preparing deuterated crystals.…”

“…In a previously studied asymmetric ladder the magnons become unstable at certain wave vectors [13]. T. Yankova et al The most recent experiments were carried out at the Cold Neutron Chopper Spectrometer CNCS [46] at Oak Ridge National Laboratory and revealed stunning new details [45]. A projection of the 4-dimensional data set onto the energy-leg momentum axes recorded during a single day on of measurement is shown in Fig.…”