Ultrafast optical tuning of ferromagnetism via the carrier density.
basic_science · Level V
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- Record sourced from PubMed, PMID 25832200.
- Also identified by DOI 10.1038/ncomms7724.
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Abstract
Interest in manipulating the magnetic order by ultrashort laser pulses has thrived since it was observed that such pulses can be used to alter the magnetization on a sub-picosecond timescale. Usually this involves demagnetization by laser heating or, in rare cases, a transient increase of magnetization. Here we demonstrate a mechanism that allows the magnetic order of a material to be enhanced or attenuated at will. This is possible in systems simultaneously possessing a low, tunable density of conduction band carriers and a high density of magnetic moments. In such systems, the thermalization time can be set such that adiabatic processes dominate the photoinduced change of the magnetic order--the three-temperature model for interacting thermalized electron, spin and lattice reservoirs is bypassed. In ferromagnetic Eu(1-x)Gd(x)O, we thereby demonstrate the strengthening as well as the weakening of the magnetic order by ~10% and within ≤3 ps by optically controlling the magnetic exchange interaction.