Microscopic correlation between magnetostriction and magnetic damping

Abstract

Although the relationship between magnetostriction and magnetic damping is often described phenomenologically, their intrinsic connection remains unclear. In this study, we demonstrate that the magnitude of magnetic damping depends on the sign of magnetostriction in ($\mathrm{Fe_{1-x}Co_{x})_{4}N}$ and $\mathrm{Ni_{1-y}Co_{y}}$ alloys across various compositions, consistent with experimental observations. This behavior is attributed to strain-induced changes in exchange splitting, which shift the minority spin density of states near the Fermi level, thereby affecting both magnetostriction and damping through spin-conserving transitions. Additionally, the presence of locally degenerate orbitals plays a crucial role in determining magnetostriction. These findings suggest that magnetization dynamics and magnetostriction can be intrinsically controlled, facilitating the design of magnetic materials for applications such as flexible spintronics.

Figures (5)

• Figure 1: Calculated magnetostriction ($\lambda_{100}$) and damping constant ($\alpha$) for (a) (Fe_1-xCo_x)_4N and (b) Ni_1-yCo_y. Crystal structure of (a) cubic Fe4N and (b) fcc-Ni, showing sites of Fe1 (black), Fe2 (blue), Fe3 (green), Fe4 (red), N (grey), and Ni (yellow) with the corresponding coordinate system
• Figure 2: Strain dependence of (a) total, (b) $\downarrow\Rightarrow\downarrow$, and (c) $\uparrow\Rightarrow\downarrow$ contribution to the MAE calculated from second-order perturbation analysis for (Fe_1-xCo_x)_4N. (d) Spin-resolved density of states of (Fe_1-xCo_x)_4N
• Figure 3: Strain dependence of the $\downarrow\Rightarrow\downarrow$ normalized orbital contribution to the MAE of the (Fe_1-xCo_x)_4N calculated from second-order perturbation analysis for (a) $d_{xz}$ - $d_{yz}$ of Fe2, (b) $d_{xz}$ - $d_{yz}$ of Fe3 (Fe4) , (c) $d_{{x}^2-{y}^2}$ - $d_{xy}$ of Fe2, and (d) $d_{{x}^2-{y}^2}$ - $d_{xy}$ of Fe3 (Fe4)
• Figure 4: Strain dependence of (a) total, (b) $\downarrow\Rightarrow\downarrow$, and (c) $\uparrow\Rightarrow\downarrow$ contribution to the MAE calculated from second-order perturbation analysis for Ni_1-yCo_y. (d) Spin-resolved density of states of fcc-Ni_1-yCo_y
• Figure 5: Strain dependence of the $\downarrow\Rightarrow\downarrow$ normalized orbital contribution to the MAE calculated from second-order perturbation analysis for (a) $d_{{x}^2-{y}^2}$ - $d_{xy}$ and (b) $d_{yz}$ - $d_{{z}^2}$ of Ni_1-yCo_y