arXiv subjects

Xuan Luo

Publications and source records attributed to Xuan Luo.

147 records · Page 9Linked to original sources

arXiv2009

Photoinduced magnetization change in multiferroic YbFe2O4

We have studied the influence of laser illumination on the magnetization in multiferroic YbFe2O4 single crystals. A photoinduced magnetization change has been confirmed in both ab plane and c axis direction. The temperature dependence of the photoinduced magnetization reduction excludes laser heating as the cause. In terms of the breakdown of charge order driven by laser illumination, the photoinduced magnetization change provides a strong evidence for the spin-charge coupling in YbFe2O4. This photomagnetic effect based on charge-order-induced multiferroicity could be used for non-thermal optical control of magnetization.

cond-mat.str-el↗

arXiv2006

Self-diffusion on Si(001) mono-hydride surfaces revisited: The role of adatom clustering

First-principles total-energy calculations of the H/Si(001)-2x1 surfaces reveals a dual diffusion process for the Si adatoms: single along the dimer row while pairing up across the row. The calculated diffusion barrier along the dimer row is 1.1 eV, which is, however, too small to account for the hydrogen-induced growth disruption seen by experiments. Instead, we find that the adatom diffusion, in the presence of H, leads to the formation of immobile fourfold-ring Si tetramers which are difficult to break. This could explain the adverse effects of H on Si homoepitaxy.

physics.comp-ph↗

arXiv2004

Jahn-Teller Distortion and Ferromagnetism in the Dilute Magnetic Semiconductors GaN:Mn

Using first-principles total-energy methods, we investigate Jahn-Teller distortions in III-V dilute magnetic semiconductors, GaAs:Mn and GaN:Mn in the cubic zinc blende structure. The results for an isolated Mn impurity on a Ga site show that there is no appreciable effect in GaAs, whereas, in GaN there is a Jahn-Teller effect in which the symmetry around the impurity changes from T$_{d}$ to D$_{2d}$ or to C$_{2v}$. The large effect in GaN occurs because of the localized d$^4$ character, which is further enhanced by the distortion. The lower symmetry should be detectable experimentally in cubic GaN with low Mn concentration, and should be affected by charge compensation (reductions of holes and conversion of Mn ions to d$^5$ with no Jahn-Teller effect). Jahn-Teller effect is greatly reduced because the symmetry at each Mn site is lowered due to the Mn-Mn interaction. The tendency toward ferromagnetism is found to be stronger in GaN:Mn than in GaAs:Mn and to be only slightly reduced by charge compensation.

cond-mat.mtrl-sci↗