I am a Romanian, born in Pitesti City. I have graduated the University and the Master courses in Physics at the West University of Timisoara, Romania . Between January 2004 and January 2008 I conducted my PhD studies (in experimental physics) within the group Spectroscopy of Solids and Interfaces at the Institute for Molecules and Materials, Radboud University Nijmegen, Nijmegen, The Netherlands. My main research topic was the study and the manipulation of magnetization by light. This broad research area has a strong impact on the density and writing/reading speed of information in magnetic data storage devices (HDD, MRAM - magnetic memory , Magneto-Optical disks, etc). Currently, I am a researcher at Océ Technologies, Venlo, The Netherlands.

This personal web page consists of general information about my curriculum, my personal interests, and the scientific research activity conducted in the previous years of my PhD. If the information presented on this web site is not enough and you would like to know more about me or my work please contact me. Critical observations are also very welcomed.

Thank you for visiting my web page!

Athermal all-optical femtosecond magnetization reversal in GdFeCo: A promising technique for stable magnetic storage with high data rates!

Magnetization reversal in GdFeCo by circularly polarized light is shown to occur at the femtosecond time scale. In contrast to the well-known laser-assisted magnetization reversal based on the laser heating, we here demonstrate that this femtosecond all-optical magnetization reversal takes place at low temperatures. Both of these findings make all-optical recording on rare-earth transition metal alloys a promising technique for stable magnetic storage with high data rates.

Figure: Schematic drawing of the time-resolved pump-probe experimental set-up used at Seagate, to measure the dynamics of all-optical switching on the femtosecond time scale.

This result has been published in the 14 April 2009 issue of Applied Physics Letters: Appl. Phys. Lett. 94, 152504 (2009)

All-optical Magnetic Recording with Circularly Polarized Light: 10.000 times faster compared with the actual magnetic recording in a Hard Disk Drive!

With this work it has been experimentally demonstrated controlled magnetization reversal induced by a single 40 femtosecond circularly polarized laser pulse in the magnetic alloy GdFeCo, a material relevant for data storage. No external magnetic field is required for this opto-magnetic switching, and the stable final state of the magnetization is unambiguously determined by the helicity of the laser pulse (see the Figure and movies bellow). This finding, previously believed to be fundamentally impossible (click here to read why), reveals an ultrafast and efficient pathway for writing magnetic bits at record-breaking speeds [1,2]. With the recent development of compact ultrafast laser systems and the successful incorporation of lasers in magnetic storage devices, the present demonstration of ultrafast all-optical magnetization reversal might spur the realization of a new generation of ultrafast magnetic recording devices [3-5].

[1] C. D. Stanciu et al.,  "All-Optical Magnetic Recording with Circularly Polarized Light", Phys. Rev. Lett, vol. 99, (2007) pp. 047601.
[2] C. D. Stanciu et al., "Ultrafast Interaction of the Angular Momentum of Photons with Spins in the Metallic Amorphous Alloy GdFeCo", Phys. Rev. Lett., vol.98, (2007) pp. 207401.
[3] David Gevaux, Nature Photonics 1, 494 (2007).
[4] Phil Berardelli, ScienceNOW, 28 June 2007.
[5] Phil Schewe and Ben Stein, Physics News Update, 830 #1, June 27, 2007.

Figure: Demonstration of compact all-optical recording of magnetic bits, achieved by scanning a circularly polarized laser beam across the sample and simultaneously modulating the polarization of the beam between left- and right circular.

Bellow you can download few movies demonstrating the effect of the angular momentum of the photons on the magnetization (all-optical magnetization reversal). You can observe how, by simply changing the helicity of light, the magnetization is reversed up or down (seen as white or black areas). The experiments were performed on a GdFeCo amorphous alloy at room temperature.

All-Optical Magnetization Reversal 1 (12 Mb)
All-Optical Magnetization Reversal 2 (11 Mb)
All-Optical Magnetization Reversal 3 (10 Mb) - in this movie SSI represents the research group Spectroscopy of Solids and Interfaces

This result has been published in the 27 July 2007 issue of Physical Review Letters (Vol.99, No.4): Phys. Rev. Lett. 99, 047601 (2007).

Sub-picosecond Magnetization Reversal Across Ferrimagnetic Compensation Points: Another way for breaking of what was previously believed the speed limit of magnetic recording !!! (read about the previous speed limt)

Sub-picosecond magnetization reversal is experimentally demonstrated by ultrafast heating a ferrimagnet across its compensation points, under an applied magnetic field. While the reversal is initiated by crossing the magnetization compensation temperature, the short reversal time is related to the angular momentum compensation, where the dynamics of the system is highly accelerated owning to the divergence of the gyromagnetic ratio. These results demonstrate the feasibility of sub-picosecond magnetization reversal previously believed impossible.

This result has been published in the 23 November 2007 issue of Physical Review Letters (Vol.99, No.21): Phys. Rev. Lett. 99, 217204 (2007).

(Last update - August 30, 2009)