Prof. Oleg Starykh (Dept. of Physics, Univ. of Utah, USA)
"Phases of spin chains with uniform Dzyaloshinskii-Moriya interactions"
In this talk I review several interesting physical phenomena that arise in systems of weakly coupled spin chains with uniform DM interaction. The first of this consists in the angle-dependent splitting of the ESR (electron spin resonance) line, which was observed experimentally soon after our theoretical prediction. Focusing on zero-temperature phase diagram of the spin-1/2 model, we next show that orthogonal to the DM axis magnetic field causes emergence of interesting Ising orders. Weak interchain interactions, which we add next, modify this picture in favor of the two-dimensional collinear spin density wave ordered state with unusual phason excitations in place of more standard spin waves. We argue that strong uniform-within-the-chain but staggered-between-the-chains DM interaction provides an alternative way of frustrating interchain exchange interactions.