High-field spin dynamics of the one-dimensional spin-½ Heisenberg antiferromagnetα−bis(N-methylsalicylaldiminato copper) (II) (α−CuNSal)

From order to randomness: Onset and evolution of the random-singlet state in bond-disordered BaCu2(Si1−xGex)2Shiroka1, Eggenschwiler2, Ott3 et al. 2019Phys. Rev. B10150View full textAdd to dashboardCite

“…While linewidths exhibit a significant increase at low T , lineshifts K(T ) are generally quite small. Even in case of single-crystalline samples, the total 29 Si NMR lineshifts are less than 0.03%, not surprising considering the 1D nature of BaCu 2 (Si 1−x Ge x ) 2 O 7 . At the same time, typical of 1D materials, the wide distribution of local Knight shifts of magnetic origin implies a strong increase of linewidths at low temperature.…”

“…The 29 Si nuclear magnetic resonance line shapes and spinlattice relaxation times T 1 were measured using standard pulsed techniques in an external field of µ 0 H = 7.07 T. The NMR measurements were restricted to samples with x ≤ 0.5, since at higher Ge content the 29 Si NMR signal progressively weakens. The field value was calibrated by means of an aluminum sample.…”

“…In previous studies, concerning the effects of randomness on the compound's magnetic properties, we focused on the extreme cases of complete order or disorder, i.e., x = 0 and x = 0.5. 21,22 The main result of bulk magnetization measurements and of low-temperature 29 Si NMR studies, supplemented by quantum Monte Carlo calculations, was the experimental verification of the theoretically predicted random-singlet state 10,11 in the x = 0.5 case. Important ingredients of this identification are the experimental determination of the probability distribution of NMR spin-lattice relaxation times T 1 and the rather unexpected (and so far unexplained) temperature dependence of T −1 1 for x = 0.5, characteristically different from that of the x = 0 case.…”

Quantum critical dynamics of anS=12antiferromagnetic Heisenberg chain studied byC

“…A αβ with α, β = x, y, z are the components of the hyperfine coupling tensor A(q). In CuPzN the 13 C nuclei are coupled to the magnetic moments of the Cu(II) electrons via isotropic hyperfine coupling A iso (q), mediating only transverse spin fluctuations, and anisotropic dipolar coupling A dip (q), mediating transverse and longitudinal spin fluctuations [32]. We want to compare the experimentally and theoretically determined T −1 1 rates for transverse fluctuations.…”

Magnetic field effects on the spin dynamics of the linear spin- Heisenberg antiferromagnet

“…Spin dynamics of the 1D HB AF (1) in nonzero magnetic field is of current experimental interest as a result of very recent neutron scattering experiments on the quasi-lD AF compounds CPC (S = 1 2 ) [3] and TMMC (S = 5 2 ) [4] both in a field of 70kOe. Active experimental investigation is also underway of proton spin-lattice relaxation rates in the quasi-lD S = 1 2 AF systems CuSeO 4 · 5H 2 O, CuSO 4 · 5H 2 O [5] and α-CuNSal [6]. This presentation is directed towards experimentalists in the hope of eventual experimental verification of the new features.…”