Abstract
We present NMR measurements of a strong-leg spin- Heisenberg antiferromagnetic ladder compound 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 , which allows us to determine the interaction parameter as a function of field. We find that field-dependent varies within the range, which signifies attractive interaction between the spinless fermions in the Tomonaga-Luttinger liquid.
- Received 1 April 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.106404
© 2013 American Physical Society