Magneto-elastic interaction

Magneto-elastic interaction involves two entities (\(X\) and \(X\) or \(Y\) and \(X\)). Therefore, it can be expressed via the terms \(\mathcal{H}_{0, 2}\) and \(\mathcal{H}_{1, 1}\).

\[\begin{split}\mathcal{H}_{0, 2} = C_{0, 2} \sum_{\substack{\mu_1, \mu_2,\\ \alpha_1, \alpha_2,\\ i_1, i_2}} V_{\mu_1, \mu_2; \alpha_1, \alpha_2}^{i_1, i_2} X_{\mu_1; \alpha_1}^{i_1} X_{\mu_2; \alpha_2}^{i_2}\end{split}\]
\[\begin{split}\mathcal{H}_{1, 1} = C_{1, 1} \sum_{\substack{\mu_1,\\ \alpha_1,\\ j_1, i_1}} V_{1; \mu_1; \alpha_1}^{j_1, i_1} Y_{1}^{j_1} X_{\mu_1; \alpha_1}^{i_1}\end{split}\]

The summary of the mapping for two terms is given in the tables below.

Magneto-elastic interaction (1)

Code

McPhase

\(\mathcal{H}\)

\[\hat{\mathcal{H}}_{ME1} = - \sum_n \sum_{\alpha=1,\dots,6, lm} G^{\alpha,l,m}_{\text{cfph}}(n) \epsilon_{\alpha} O_{lm}(\hat{\mathbf{J}}^n)\]

Indices renaming

\(n \rightarrow (\mu_1; \alpha_1)\), \((l,m) \rightarrow i_1\), \(\alpha \rightarrow j_1\)

\(C_{1, 1}\)

\(-1\)

\(V_{1; \mu_1; \alpha_1}^{j_1,i_1}\)

\(G^{\alpha, i_1}_{\text{cfph}}(\mu_1,\alpha_1)\)

\(Y_{1}^{j_1}\)

\(\epsilon_{j_1}\)

\(X_{\mu_1; \alpha_1}^{i_1}\)

\(O_{i_1}(\hat{\mathbf{J}}^{\mu_1, \alpha_1})\)

Magneto-elastic interaction (2)

Code

McPhase

\(\mathcal{H}\)

\[\begin{split}\hat{\mathcal{H}}_{ME2} = - \sum_{\substack{n<n^{\prime},lm,\\\alpha=1,2,3}} \Gamma^{\alpha,l,m}(nn^{\prime}) \hat{u}_n^{\alpha} O_{lm}(\hat{\mathbf{J}}^{n^{\prime}})\end{split}\]

Indices renaming

\(n \rightarrow (\mu_1; \alpha_1)\), \(n^{\prime} \rightarrow (\mu_2; \alpha_2)\), \(\alpha \rightarrow i_1\), \((l,m) \rightarrow i_2\)

\(C_{0, 2}\)

\(-1\)

\(V_{\mu_1, \mu_2; \alpha_1, \alpha_2}^{i_1, i_2}\)

\(\Gamma^{i_1, i_2}(\mu_1, \alpha_1, \mu_2, \alpha_2)\)

\(X_{\mu_1; \alpha_1}^{i_1}\)

\(\hat{u}_{\mu_1, \alpha_1}^{i_1}\)

\(X_{\mu_2; \alpha_2}^{i_2}\)

\(O_{i_2}(\hat{\mathbf{J}}^{\mu_2, \alpha_2})\)

Note

  • Pair of indices \((l,m)\) run over the finite set of the sets of two integers. Therefore, they can be enumerated with a single integer and mapped to the index \(i_1\) (\(i_2\)).

  • In the case of \((2)\), index \(i_1 = x, y, z\), while index \(i_2\) runs over all pairs of integers \((l,m)\) of the original Hamiltonian.