5th Workshop on ab initio phonon calculations

Phonon confinement and spin-phonon coupling in tensile-strained thin EuO films

5 Dec 2019, 15:00

35m

Main lecture hall (Institute of Nuclear Physics PAN)

Talk

Speaker

Svetoslav Stankov (Laboratory for Applications of Synchrotron Radiation and Institute for Photon Science and Synchrotron Radiation, Karlsruhe Institute of Technology, Germany)

Description

Europium monoxide (EuO) is the first rare-earth semiconducting oxide known for its giant magneto-optic Kerr [1] and Faraday [2] effects, metal-to-insulator transition and anomalous Hall effect [4]. Presently, it is one of the favored candidates for applications as a spin filter in future spintronic devices due to the large exchange splitting of its conduction band [5]. Employing inelastic X-ray scattering, nuclear inelastic scattering and first-principles theory we determined the lattice dynamics of this material and discovered a giant and anisotropic spin-phonon coupling [6]. This discovery imposed an intriguing question about the manifestation of this phenomenon in thin and ultrathin films related to the proposed applications. Using $\textit{in situ}$ nuclear inelastic scattering on $^{151}$Eu we investigated the phonon density of states of EuO films with thickness between 8 nm and of 1 atomic layer. The experimental results unveiled drastic lattice dynamics modifications in the ultrathin EuO films that can be comprehensively understood by the help of first-principles theory [7].

S. S. acknowledges the financial support by the Helmholtz Association (VH-NG-625) and BMBF (05K16VK4). A.\ M.\ O.\ kindly acknowledges support by National Science Centre (NCN) under Project No.\ 2016/23/B/ST3/00839 and the Alexander von Humboldt Fellowship (Humboldt-Forschungspreis). P. P. acknowledges support by NCN under Project No. 2017/25/B/ST3/02586 and the access to ESRF financed by the Polish Ministry of Science and High Education – decision number: DIR/WK/2016/19.

Refs
[1] J. H. Greiner and G. J. Fan, Appl. Phys. Lett. {\bf 9}, 27 (1966).
[2] K. Y. Ahn, J. Appl. Phys. {\bf 41}, 1260 (1970).
[3] Y. Shapira, S. Foner and R. Aggarwal, Phys. Rev. B {\bf 8}, 2316 (1973).
[4] P. G. Steeneken {\it et al.}, Phys. Rev. Lett. {\bf 88}, 047201 (2002).
[5] R. Pradip {\it et al.}, Phys. Rev. Lett. {\bf 116}, 185501 (2016).
[6] R. Pradip {\it et al.}, Nanoscale {\bf 11}, 10968 (2019).