Ultrafast magnetization dynamics of Mn-doped L10 FePt with spatial inhomogeneity

•Fluence-dependent measurements for different concentrations of Mn-doped FePt.•Combination of experimental techniques.•Application of different theoretical models.•Layer-sensitive ultrafast measurements.•Importance of sample preparation procedure. One of the persisting goals in the field of femtomag...

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Bibliographic Details
Published in:Journal of magnetism and magnetic materials 2020-05, Vol.502, p.166477, Article 166477
Main Authors: Liu, Yuting, Bierbrauer, Ute, Seick, Cinja, Weber, Sebastian T., Hofherr, Moritz, Schmidt, Natallia Y., Albrecht, Manfred, Steil, Daniel, Mathias, Stefan, Schneider, Hans Christian, Rethfeld, Baerbel, Stadtmüller, Benjamin, Aeschlimann, Martin
Format: Article
Language:English
Subjects:
Demagnetization
Dynamics
FePt
Ferrous alloys
Fluence
Inhomogeneity
Intermetallic compounds
Iron compounds
Kerr effects
Kerr magnetooptical effect
Magnetic alloys
Magnetic properties
Magnetism
Magnetization
Manganese
Platinum compounds
Quenching
Secondary ion mass spectrometry
Time constant
Ultrafast demagnetization
Ultrafast magnetization dynamics
Ultrafast spin dynamics
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Summary:•Fluence-dependent measurements for different concentrations of Mn-doped FePt.•Combination of experimental techniques.•Application of different theoretical models.•Layer-sensitive ultrafast measurements.•Importance of sample preparation procedure. One of the persisting goals in the field of femtomagnetism is to study and understand the light-induced ultrafast magnetization dynamics of magnetic model systems and multi-compound materials. The latter offers the intriguing opportunity to tune and control the static as well as the transient magnetic properties of the materials according to the desired field of application. Here, we focus on the ultrafast magnetization dynamics of the technologically relevant FePt alloy doped with different concentrations of manganese (Mn) atoms. We find that the demagnetization time constant τm of FePt decreases significantly upon Mn doping coinciding with a more energy efficient demagnetization process, i.e., the required laser fluence for a certain quenching of the magnetization reduces with increasing Mn concentration. Even more interesting, the characteristic demagnetization time vs. quenching curve does not reveal a single-peak curve as expected from the microscopic three-temperature model, but exhibits a double-hump signature. This peculiar behavior can be explained by the existence of a depth dependent variation of the Mn concentration in the FePt host material. It is caused by the sample preparation procedure using rapid thermal annealing as demonstrated experimentally by layer-sensitive magneto-optical Kerr effect experiments and secondary ion mass spectrometry. Our findings underline the crucial role of the sample preparation procedure for the transient magnetization dynamics of complex magnetic alloys.
ISSN:0304-8853
1873-4766
DOI:10.1016/j.jmmm.2020.166477