This work was carried out under the co-direction of Dr. Christine Boegli (DSI) and Dr. Matthieu Bailleul (DMONS).
The defense will take place on Friday, September 22th at 2:00 p.m. in the IPCMS’ Auditorium
PhD defense : Gaëtan PERCEBOIS
These works were carried out under the supervision of Dietmar Weinmann at IPCMS in the DMONS department.
The defense will take place on Friday, September 29th, 2023 at 10:00 a.m: in the IPCMS auditorium.
Seminar DON, axes 1 and 4 presented Abdelghani Laraoui
Abdelghani Laraoui (Department of Mechanical & Materials Engineering, University of Nebraska-Lincoln)
Abstract :
Magnetic microscopy based on nitrogen vacancy (NV) centers in diamond has become a versatile tool to detect magnetic fields with an unprecedented combination of spatial resolution and magnetic sensitivity, opening up new frontiers in biological [1] and condensed physics matter research [2]. In this seminar, I will present two examples of using NV magnetic microscopy in both scanning probe microscopy (SPM) and wide-field microscopy (WFM) geometries to study nanoscale magnetic phenomena in different materials. First, I will discuss NV-SPM measurements of antiferromagnetic (AFM) domains switching in Cr2O3 and B-Cr2O3 thin films and device structures [3, 4]. Cr2O3 is an archetypical AFM oxide that permits voltage-control of the Néel vector. In addition, boron doping increases Néel temperature from 307 K to 400 K and allows realizing voltage controlled Néel vector at zero applied magnetic field, a promising finding to AFM spintronics. Then, I will discuss NV-WFM measurements on individual Fe(Htrz)2(trz)](BF4)] (Fe triazole) spin-crossover (SCO) nano-rods of size varying from 20 to 1000 nm [5]. Fe triazole SCO complexes exhibit thermal switching between low spin (LS) and high spin (HS) states which are applicable in thermal sensors and molecular switches. While the bulk magnetic properties of these molecules are widely studied by bulk magnetometry techniques their properties at the individual level are missing. The stray magnetic fields produced by individual Fe-triazole nano-rods are imaged by NV magnetic microscopy as a function of temperature (up to 150 0C) and applied magnetic field (up to 3500 G). We found that in most of the nanorods the LS state is slightly paramagnetic, possibly originating from the surface oxidation and/or the greater Fe(III) presence along the nanorods’ edges [5].
References: [1] I. Fescenko, A. Laraoui, et al., Phys. Rev. App. 11, 034029 (2019). [2] A. Laraoui and K.
Ambal, Appl. Phys. Lett. 121, 060502 (2022). [3] A. Erickson, A. Laraoui, et al., RSC Adv. 13, 178-185 (2023).
[4] A. Erickson, A. Laraoui, et al., to be submitted to Nat. Mat. (2023). [5] S. Lamichhane, A. Laraoui, et al.,
ACS Nano 17, 9, 8694–8704 (2023).
Contact : Valérie Halté (valerie.halte@ipcms.unistra.fr)
Defense of Habilitation to Supervise Research : Walid BAAZIZ
Walid BAAZIZ (IPCMS / DSI)
Composition du jury :
Rapporteurs : Sophie Carenco DR, CNRS (LCMCP) – Université de Sorbonne
Gilles Patriarche DR, CNRS (C2N) – Université de Paris-Saclay
Lucian Roiban MCF, (Matéis) INSA, Lyon
Examinateurs : Corinne Petit Professeure, Université Strasbourg
Pierre Rabu DR, CNRS (IPCMS) – Université de Strasbourg
Garant : Ovidiu Ersen Professeur, Université de Strasbourg
Seminar DSI and DCMI presented by Prof. Ulrich Lorenz
Prof. Ulrich Lorenz, Ecole Polytechnique Fédérale de Lausanne (Suisse)
Abstract :
It was recognized over 40 years ago that the key to understanding the origin of the anomalous
properties of water lies in the deeply supercooled regime, from where they appear to
emanate. Most vexingly however, water crystallizes rapidly between 160 K and 232 K, which
has made any systematic characterization in this temperature range, the so-called “no man’s
land”, largely elusive. We have recently introduced a novel approach to rapidly prepare water
in no man’s land and probe it with electron diffraction before crystallization occurs. We show
that as water is cooled from room temperature to cryogenic temperature, its structure evolves
smoothly, which narrows down the range of possible explanations for the origin of the water
anomalies.
A twist on the same experimental approach allows us to use it to observe the dynamics of
proteins. Proteins provide the machinery of life; however, our understanding of their function
has remained fundamentally incomplete, as observing them in action has largely remained
elusive. Recently, my group has introduced microsecond time-resolved cryo-electron
microscopy, a novel technique enabling such observations, with near-atomic spatial and
microsecond temporal resolution. I will discuss the features of our method and present
observations of the motions of the capsid of CCMV, a plant virus, which illustrate the potential
of our technique to fundamentally advance our understanding of proteins.
Contact : Florian BANHART (florian.banhart@ipcms.unistra.fr)
PhD defense : Thomas ALLARD
These works were carried out under the supervision of Guillaume Weick at IPCMS in the DMONS department.
The defense will take place on Wednesday, September 27th, 2023 at 2:00 PM in the IPCMS auditorium.