Ferromagnetism of transition metals and screened exchange interactions

Abstract

We have investigated the magnetic properties of Fe, Co, and Ni at finite temperatures on the basis of the first-principles dynamical coherent potential approximation (CPA) in order to clarify the role of the exchange interaction energy ($J$) screened by {\it sp} electrons and its applicability to finite-temperature magnetism. With use of the atomic $J$, we obtained the Curie temperatures ($T_{\mathrm{C}}$) 1930 K for Fe and 2550 K for fcc Co, which are overestimated by a factor of 1.8 as compared with the experimental values, while we obtained $T_{\mathrm{C}}=620$ K for Ni being in good agreement with the experiment. Calculated effective Bohr magneton numbers also quantitatively agree with the experimental values. By comparing the results with those obtained by the screened $J$ and by comparing them with the experiments, we found that the screened $J$, which are reduced by 30% as compared with the atomic ones, improve the ground-state magnetizations and densities of states at low temperatures in Fe and fcc Co, as well as $T_{\mathrm{C}}$ in fcc Co. But the screened $J$ yield worse results for finite temperature properties of Fe and underestimate both the ground-state magnetization and $T_{\mathrm{C}}$ in case of Ni. We discuss possible origins for these inconsistencies.

10 pages, 7 figure, to be published in Phys. Rev. B

References in corpus (7)

• First-principles Calculations of the Electronic Structure and Spectra of Strongly Correlated Systems: Dynamical Mean-field Theory
• Calculations of Hubbard U from first-principles
• Screened Coulomb interaction in the maximally localized Wannier basis
• Systematic and Causal Corrections to the Coherent Potential Approximation
• Electronic structure and effects of dynamical electron correlation in ferromagnetic bcc-Fe, fcc-Ni and antiferromagnetic NiO
• Dynamical coherent-potential approximation approach to excitation spectra in 3d transition metals
• Evidence of Strong Electron Correlations in Gamma-Iron

Cited by in corpus (6)

• Tuning the laser-induced ultrafast demagnetization of transition metals
• First-Principles Theory of Momentum Dependent Local Ansatz Approach to Correlated Electron System
• First-Principles Momentum Dependent Local Ansatz Approach to the Momentum Distribution Function in Iron-Group Transition Metals
• First-Principles Momentum Dependent Local Ansatz Approach to the Ground-State Properties of Iron-Group Transition Metals
• Dynamical nonlocal coherent-potential approximation for itinerant electron magnetism
• Momentum-Dependent Local Ansatz Approach to the Metallic Ferromagnetism