A $^{51}$V NMR Investigation of the Quasi-1D Antiferromagnet BaCo$_{2}$V$_{2}$O$_{8 }$: Is there a New ordered Phase?

We report on detailed $^{51}$V ( I=7/2) NMR spectral and spin-lattice relaxation time (T$_{1})$ measurements on the quasi-1D antiferromagnet BaCo$_{2}$V$_{2}$O$_{8}$. Our major focus was on probing the possible existence of the new ordered state in its field-induced phase above the critical field H$_{c}$=3.9T. This phase is believed to be of the incommensurate type, and thus quite amenable to investigation by NMR line shape and T$_{1}$ measurements. T$_{1}$ data were obtained using a spin-echo pulse sequence. Measurements were done on a single crystal, with the field parallel to the easy axis (c-axis). Details of the lineshape and T$_{1}$ analysis in terms of the evolution of the anticipated new phase will be presented.