We use ultrafast x-ray and electron diffraction to disentangle spin-lattice coupling of granular FePt in the time domain. The reduced dimensionality of single-crystalline FePt nanoparticles leads to strong coupling of magnetic order and a highly anisotropic three-dimensional lattice motion characterized by a- and b-axis expansion and c-axis contraction. The resulting increase of the FePt lattice tetragonality, the key quantity determining the energy barrier between opposite FePt magnetization orientations, persists for tens of picoseconds. These results suggest a novel approach to laser-assisted magnetic switching in future data storage applications.
@article{arxiv.1602.04519,
title = {Beyond a phenomenological description of magnetostriction},
author = {A. H. Reid and X. Shen and P. Maldonado and T. Chase and E. Jal and P. Granitzka and K. Carva and R. K. Li and J. Li and L. Wu and T. Vecchione and T. Liu and Z. Chen and D. J. Higley and N. Hartmann and R. Coffee and J. Wu and G. L. Dakowski and W. Schlotter and H. Ohldag and Y. K. Takahashi and V. Mehta and O. Hellwig and A. Fry and Y. Zhu and J. Cao and E. E. Fullerton and J. Stöhr and P. M. Oppeneer and X. J. Wang and H. A. Dürr},
journal= {arXiv preprint arXiv:1602.04519},
year = {2017}
}