Small-scale phase separation in doped anisotropic antiferromagnets

TL;DR

This paper investigates nanoscale phase separation in doped anisotropic antiferromagnets, focusing on the formation and energetics of ferromagnetic droplets in 2D and 3D systems, revealing universal parameters governing their shape and stability.

Contribution

It introduces a model for ferromagnetic droplet formation in doped anisotropic antiferromagnets, deriving universal parameters that determine droplet shape and energy in 2D and 3D.

Findings

Droplet shape is elliptical in 2D and ellipsoidal in 3D.

Binding energy depends on universal parameters $ar{J}$ and $t_{eff}$.

Energy calculations show the most favorable droplet configurations.

Abstract

We analyze the possibility of the nanoscale phase separation manifesting itself in the formation of ferromagnetic (FM) polarons (FM droplets) in the general situation of doped anisotropic three- and two-dimensional antiferromagnets. In these cases, we calculate the shape of the most energetically favorable droplets. We show that the binding energy and the volume of a FM droplet in the three-dimensional (3D) case depend only upon two universal parameters $\bar{J} =(J_x + J_y + J_z)S^2$ and $t_{eff} =(t_xt_yt_z)^{1/3}$, where $\bar{J}$ and $t_{eff}$ are effective antiferromagnetic (AFM) exchange and hopping integrals, respectively. In the two-dimensional (2D) case, these parameters have the form $\bar{J} =(J_x + J_y)S^2$ and $t_{eff} =(t_xt_y)^{1/2}$. The most favorable shape of a ferromagnetic droplet corresponds to an ellipse in the 2D case and to an ellipsoid in the 3D case.