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Femtosecond optical reflectivity measurements of lattice-mediated spin repulsions in photoexcited LaCoO3 thin films

Johan Bielecki (Institutionen för teknisk fysik, Kondenserade materiens fysik) ; A. D. Rata ; Lars Börjesson (Institutionen för teknisk fysik, Kondenserade materiens fysik)
Physical Review B. Condensed Matter and Materials Physics (1098-0121). Vol. 89 (2014), 3, p. art. no. 035129.
[Artikel, refereegranskad vetenskaplig]

We present results on the temperature dependence of ultrafast electron and lattice dynamics, measured with pump-probe transient reflectivity experiments, of an epitaxially grown LaCoO3 thin film under tensile strain. Probing spin-polarized transitions into the antibonding e(g) band provides a measure of the low-spin fraction, both as a function of temperature and time after photoexcitation. It is observed that femtosecond laser pulses destabilize the constant low-spin fraction (similar to 63%-64%) in equilibrium into a thermally activated state, driven by a subpicosecond change in spin gap Delta. From the time evolution of the low-spin fraction, it is possible to disentangle the thermal and lattice contributions to the spin state. A lattice mediated spin repulsion, identified as the governing factor determining the equilibrium spin state in thin-film LaCoO3, is observed. These results suggests that time-resolved spectroscopy is a sensitive probe of the spin state in LaCoO3 thin films, with the potential to bring forward quantitative insight into the complicated interplay between structure and spin state in LaCoO3.

Nyckelord: TRANSITIONS, MANGANITE, PULSES



Denna post skapades 2014-08-21. Senast ändrad 2015-01-21.
CPL Pubid: 201764

 

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Institutioner (Chalmers)

Institutionen för teknisk fysik, Kondenserade materiens fysik (1900-2015)

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Chalmers infrastruktur

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