  We study solutions for a rotating string on S^3 with a background NS-NS
B-field and show the existence of spiky string and giant magnon as two limiting
solutions. We make a connection to the sine-Gordon model via the Polyakov
worldsheet action and study the effect of B-field. In particular, we find the
magnon solution can be mapped to the excitation of a fractional spin chain. We
conjecture a B-deformed SYM to be the gauge theory dual to this background.
