Lucian PREJBEANU

Spintronique et Technologie des Composants

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Present position:

Executive Director of SPINTEC, UMR CEA-CNRS-UGA-G-INP

 

Summary:

Lucian has been conducting research on nanomagnetism and spintronics for more than 15 years. He holds a Physics degree from Babes Bolyai University in Cluj (Romania) and a PhD in Physics from Louis Pasteur University in Strasbourg where he pioneered the work on magnetic nanostructures. He then joined SPINTEC research laboratory in Grenoble, where he pioneered scientific work on thermally assisted MRAM, tackling the key long-standing problem of bits stable enough for long-term storage, yet still easy to write with small magnetic fields. Based on this proof-of-principle of the scientific concepts, Crocus Technology was founded in 2006 to develop and commercialize thermally assisted MRAM technology. Lucian joined Crocus Technology mid-2006 as R&D manager, where he made key contributions to the development and industrialization of thermally assisted MRAM for which he was awarded the SEE-IEEE Brillouin prize in 2012. In 2013, Lucian returns to Spintec as deputy director and became executive director as of January 1st, 2016. He holds 38 international patents on magnetic memories and has authored more than 70 scientific publications and book chapters on nanomagnetism and spintronics.

Career:

January 2016 – : Executive Director, SPINTEC

February 2013 – December 2015 : Deputy Director, SPINTEC

August 2006 – January 2013: R&D Manager, Crocus Technology

Management and expertise of magnetic materials for thermally assisted or STT-MRAMs

December 2004 – July 2006 : CEA/INAC engineer, SPINTEC, Grenoble

MRAM technology advisor for the fund raising and the creation of Crocus Technology

Magnetic logic :based on extraordinary Hall effect & using domain wall movement in magnetic

structures with perpendicular magnetization

Magnetic storage : STT based writing based from a near field nanometric tip

April 2003 – November 2004 : Postdoc CEA/INAC, SPINTEC, Grenoble

Thermally assisted MRAMs: first demonstration of the thermally assisted MRAMs with an exchange biased storage layer

March 2002 – March 2003 : Postdoc CNRS, Louis Néel laboratory & SPINTEC Grenoble

Magnetic storage: patterned media and writing by heating the dots by a near field nanometric AFM tip

November 1998 – February 2002 : PhD, IPCMS (Institut de Physique et Chimie des Matériaux de Strasbourg)

Nanomagnetism, spin electronics: domain wall magnetoresistance in nanowires & effect of dipolar

interactions on the reversal of the magnetization

October 1997 – November 1998 : R&D engineer, INCDTIM (National institut for research & development of the isotopic and molecular technologies, Cluj-Napoca, Romania

Molecular Physics : multi-fotonic dissociation of molecules in laser radiation field

March 1997 – July 1997 : Master of Science, LMGP (Laboratoire de Matériaux et de Génie Physique) - INPG Grenoble

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Refractory materials :low temperature preparation of ultra-refractory nanocompounds

March 1996 – June 1996: Bachelor of Science, Institut de recherche en physique de l’Université Babes Bolyai, Cluj Napoca, Roumanie

NdFeB permanent magnets : preparation & magnetic caracterisation

Training and diploma:

Habilitation (Grenoble INP, Grenoble) – defended in 2015

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2001 : PhD in physics – condensed matter & materials

Louis Pasteur University & Institut de Physique et Chimie des Matériaux de Strasbourg

1998 : Master of Science - condensed matter & materials

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Babes-Bolyai University, Cluj-Napoca, Romania & INPG Grenoble

1997 : Bachelor in physics - condensed matter & materials

Babes-Bolyai University, Cluj-Napoca, Romania

Publications & patents

Published over 70 papers in scientific journals & chapters in scientific books (Springer Verlag, NATO Science Series) - H-index : 18

Holds 39 patents filed, at different stages (granted, published, provisional pending)

General context of my work

The research of new approaches to making non-volatile memories has been a major activity of SPINTEC since its inception. SPINTEC research laboratory was established in 2000 to specifically work at valuation of upstream work in the areas of nanomagnetism and spintronics. The MRAM team in SPINTEC has proposed alternative MRAM technologies with improved performances (speed, scalability and power consumption) and avoiding problems like the write selectivity, power consumption, electromigration and thermal stability at high densities. Multiple approaches have been pursued in parallel:

Spintec has been amongst the pioneers in MRAM development and is recognized worldwide as such. Consequently, we have / have had multiple partnerships with laboratories, research centers and companies, through joint R&D projects (ANR, EU), as well as bilateral industry partnerships. A preferred relation exists with Crocus, which led to the onset of a 5 years “joint laboratory” signed in 2013.

Based on patents filed between 2001 and 2005, a new technology of non-volatile magnetic memories, thermally assisted has been demonstrated by Spintec. The originality of this technology stems from the specific writing process that combines a short heating pulse sent through the memory cell (few nanoseconds) with a magnetic field pulse or a spin polarized current. The very convincing results obtained by SPINTEC and LETI in the framework of the NEXT European project between 2001 and 2005 enabled the launch of a start-up Grenoble, Crocus-Technology, which has managed to raise 13.5 Million Euros from venture capitals in 2006. This transaction also received the grand prize of the ANVAR innovation in 2005 and was a finalist EU Descartes Prize in 2006.

Since the first demonstration of the TAS-MRAM concept in 2004, several improvements / variations of this technology have been proposed:

  1. The concept of heat assistance can be advantageously coupled to writing by spin-polarized current to significantly improve the thermal stability in STT-based systems. The use of spin transfer as writing means offers much better prospects for decreasing sizes than writing magnetic field. Indeed with the spin transfer, the write current decreases as the cell size while in the field writing, the write current rather tends to increase as the size decreases. However, the STT-RAM suffers from the same problem as the MRAM standards in terms of thermal stability for small sizes. TA-STT-RAM concept (Thermally Assisted Spin Transfer Torque RAM) allows to ensure higher MRAM densities while minimizing the write current. In this concept, the same current flowing through the tunnel junction makes heats by Joule effect and exerts magnetic torque by spin transfer torque phenomenon. The concept of TA-STT-RAM was developed within the framework of a bilateral agreement between CEA and Crocus and a ANR 2007 "RAMAC," (Technology Roadmap for Advanced MRAM).
  2. Recently, the joint R&D teams from Crocus in Spintec developed a self-referenced reading concept which now serves as building block for the company's products. This new concept makes the memory much more tolerant to process variations and very promising for security applications (smart cards, routers, biometrics). Technological advances have enabled obtained Crocus growing dramatically, as evidenced by one of the latest fund-raising 300M€ in 2011 enabling him to go live with one of the first full magnetic back-end fab worldwide.
  3. In addition, the research work carried out in close collaboration with SPINTEC allowed several advances at the highest international level of research on MRAM: the ultra-low power memories combining writing to the local heating spin polarized current TAS-STT of systems with perpendicular anisotropy.

 

 

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