Field-induced antiferromagnetism and Tomonaga-Luttinger liquid behavior in the quasi-one-dimensional Ising-Antiferromagnet SrCo2V2O8

Abstract

We investigate the low-temperature properties of the Ising-like screw chain antiferromagnet SrCo2V2O8 under a longitudinal magnetic field by susceptibility and 51 V NMR measurements. The bulk susceptibility χ shows an onset of long-range Ising-antiferromagnetic (AFM) order and the suppression of the order by field with the Néel temperature dropped from 5.1 K to 2 K when field increases from 0.1 T to 4 T. The suppression of the AFM order by the field is also observed by the NMR spectra and the spin-lattice relaxation 1/T1. At fields above 4 T, χ shows a low-temperature upturn, which is consistent with the onset of a transverse antiferromagnetic order as supported by the quantum Monte Carlo simulations. A line splitting in the NMR spectra is also observed at high temperatures. We show that the line split characterizes the onset of a short-range transverse antiferromagnetic order with magnetic moments orientated along the crystalline [110]/[1 10] directions. The 1/T1 data at higher temperature show a power-law behavior 1/T1∼T α , which is consistent with the Tomonaga-Luttinger-liquid behavior. With increasing the field, the power-law exponent α changes from negative to positive, which clearly shows an inversion of the Luttinger exponent η, where the dominant low-energy spin fluctuations switch from the longitudinal type to the transverse type at a high field of 7 T.