Quantum spin nematics: Moment-free magnetism

Abstract

Treating antiferromagnetism as a spin superfluid, we discuss the possibility of moment-free magnetism. Specifically we show that large quantum fluctuations induce an anisotropy in Heisenberg spiral structures, driving a biaxial-uniaxial transition to a spin nematic; this state is characterized by tensor spin order and a gapless Goldstone mode of spin-pair excitations. Experimental signatures and realizations of this phenomena are suggested.