Juexian Cao

Rigid band model for prediction of magnetostriction of iron-gallium alloys

Using the highly precise full potential linearized augmented plane wave method, we determined atomic structure and the magnetostriction of Fe100−xGax with x<19%. It is demonstrated that the extraordinary enhancement of magnetostrictive coefficient of Fe100−xGax at low concentration stems from intrinsic electronic origins. Moreover, we recognized the potential of using a rigid band model for the prediction of magnetostriction of intermetallic alloys, through studies of ternary alloys with Zn substitution into Fe87.5Ga12.5.Using the highly precise full potential linearized augmented plane wave method, we determined atomic structure and the magnetostriction of Fe100−xGax with x<19%. It is demonstrated that the extraordinary enhancement of magnetostrictive coefficient of Fe100−xGax at low concentration stems from intrinsic electronic origins. Moreover, we recognized the potential of using a rigid band model for the prediction of magnetostriction of intermetallic alloys, through studies of ternary alloys with Zn substitution into Fe87.5Ga12.5.

Magnetization and magnetic anisotropy of metallophthalocyanine molecules from the first principles calculations

Using the full potential linearized augmented plane wave method, we explored the magnetic anisotropy energies of metallophthalocyanine molecules with Mn, Fe, Co, and Ni. Their spin magnetic moments can be expressed as 8−nμB (n=5,6,7,8 for Mn, Fe, Co, and Ni). Interestingly, Mn-phthalocyanine has a large orbital magnetic moment of 0.19μB and a sizable magnetic anisotropy energy of 2.72 meV useable for applications.

Real-Space Imaging of Kondo Screening in a Two-Dimensional O2 Lattice

Rows of paramagnetic oxygen molecules adsorbed on a gold surface exhibit both deconfined and localized Kondo screening. Kondo lattice systems can exhibit unusual many-body behaviors that result from the interplay between onsite Kondo screening and intersite coupling. We used scanning tunneling microscopy to image the Kondo resonance in a nonconventional Kondo lattice formed by self-assembled oxygen (O2) molecules, which are paramagnetic, on the gold reconstructed surface [Au(110)-1×2]. The interplay between the intermolecular coupling for molecules adsorbed along chains and the onsite Kondo effect leads to the coexistence of both local and nonlocal Kondo screening at the atomic level. The latter provides evidence for collective deconfinement of magnetization induced in Au, whereas the former shows local “hybridization” between the Kondo clouds of nearest-neighbor O2 molecules.

Structural Understanding of Self-Assembled Rare Earth Disilicide Nanostructures Via Scanning Probe Microscopy and First Principles Studies

We performed systematic experimental and computational studies to investigate the adsorption geometries of Y atoms on the Si(001) surface. This paves a way for understanding and eventually controlling the growth of rare earth disilicide wires on the Si(001) substrate that are promising for various applications. For a single Y atom, the interrowdn site was found to be at least 400 meV lower in energy than other possible binding sites. The emulated STM images are in good agreement with experimental results of Er on Si(001). The strong bias and coverage dependence indicates the need for theoretical guidance for the correct interpretation of experimental data. We elucidate the Y-Si binding mechanism and provide insights toward the onset of formation of hexagonal rare earth disilicide wires.