M. Kopecky | Searcharxiv

arXiv2026

Limitations of Debye-Waller lattice temperature extraction under electronic excitation

Ultrafast diffraction is the cutting-edge technique to extract the atomic temperature at femtosecond timescales, and further related quantities - in particular, electron-phonon coupling strength at elevated electronic temperatures. The present work demonstrates limitations of such an analysis, emphasizing the importance of careful evaluation of the evolution of the Debye temperature. It is shown that, due to the sensitivity of the Debye-Waller analysis to this parameter, neglecting its changes under electronic excitation may lead to significant deviations of the atomic temperature extracted from its true values.

cond-mat.mtrl-sci↗

arXiv2010

Detection of stacking faults breaking the [110]/[1-10] symmetry in ferromagnetic semiconductors (Ga,Mn)As and (Ga,Mn)(As,P)

We report high resolution x-ray diffraction measurements of (Ga,Mn)As and (Ga,Mn)(As,P) epilayers. We observe a structural anisotropy in the form of stacking faults which are present in the (111) and (11-1) planes and absent in the (-111) and (1-11) planes. The stacking faults produce no macroscopic strain. They occupy 0.01 - 0.1 per cent of the epilayer volume. Full-potential density functional calculations evidence an attraction of Mn_Ga impurities to the stacking faults. We argue that the enhanced Mn density along the common [1-10] direction of the stacking fault planes produces sufficiently strong [110]/[1-10] symmetry breaking mechanism to account for the in-plane uniaxial magnetocrystalline anisotropy of these ferromagnetic semiconductors.

cond-mat.mtrl-sci↗