Magnetic anisotropy barrier for spin tunneling in Mn{sub 12}O{sub 12} molecules
- Center for Computational Materials Science--6392, Naval Research Laboratory, Washington, D.C. 20375-5000 (United States)
- Department of Physics, Virginia Commonwealth University, Richmond, Virginia 23284-2000 (United States)
Electronic structure calculations on the nature of electronic states and the magnetic coupling in Mn-acetate [Mn{sub 12}O{sub 12}(RCOO){sub 16}(H{sub 2}O){sub 4}] molecules have been been carried out within the generalized gradient approximation to the density functional formalism. Our studies on this 100-atom molecule illustrate the role of the nonmagnetic carboxyl host in stabilizing the ferrimagnetic Mn{sub 12}O{sub 12} core and provide estimates of the local magnetic moment at the various sites. We provide a first density-functional-based prediction of the second-order magnetic anisotropy energy of this system. Results are in excellent agreement with experiment. To perform these calculations we introduce a simplified exact method for spin-orbit coupling and magnetic anisotropy energies in multicenter systems. This method is free of shape approximations and has other advantages as well. First, it is valid for periodic boundary conditions or finite systems and is independent of basis set choice. Second, the method does not require the calculation of electric field. Third, for applications to systems with a finite energy gap between occupied and unoccupied electronic states, a perturbative expansion allows for a simple determination of the magnetic anisotropy energy. {copyright} {ital 1999} {ital The American Physical Society}
- OSTI ID:
- 686565
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 60, Issue 13; Other Information: PBD: Oct 1999
- Country of Publication:
- United States
- Language:
- English
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