Magnetic Phase Diagram of a 2D $XY$ Model with Random Easy Axis Orientation

K. Ideura

Jonathan D’Emidio, Ribhu K. Kaul

Cesar A. Gallegos, Shengtao Jiang, Steven R. White +1 more

The phase diagram of the S=1/2 easy-axis triangular-lattice J_{1}-J_{2} model is investigated using the density-matrix renormalization group and analytical insights. We find a significant spin-liquid region extending from the Heisenberg limit and residing between the Y phase-known as the magnetic analogue of the "supersolid"-and collinear stripe phase. The order parameters of the supersolid are analyzed and an understanding of its lack of a ferromagnetic moment is suggested.

Виктор Степанович Доценко, G. Uimin

Hong-Hao Song, Long Zhang

The boundary critical behavior of the two-dimensional (2D) quantum antiferromagnetic (AF) XXZ model coupled with either a dangling $\mathrm{spin}\text{\ensuremath{-}}1/2$ XXZ chain or a dangling two-leg ladder on the boundary is studied with the bosonization and renormalization group analysis. A rich boundary phase diagram is obtained in each case. In the dangling chain case, the boundary either develops a long-range AF order in the easy-plane or the easy-axis direction with extraordinary critical behavior or has a valence bond solid order with ordinary boundary critical behavior. In the case of a dangling two-leg ladder, besides the possible easy-plane or easy-axis AF-ordered phases on the boundary with extraordinary critical behavior, the boundary can form a singlet phase with ordinary critical behavior without breaking any symmetry. These results are consistent with recent numerical simulations on the boundary critical behavior of 2D quantum spin models.

Àlex Arenas, C. J. Pérez Vicente