arXiv subjects

C. Dubourdieu

Publications and source records attributed to C. Dubourdieu.

4 recordsLinked to original sources

arXiv2023

Charge-Trapping-Induced Compensation of the Ferroelectric Polarization in FTJs: Optimal Conditions for a Synaptic Device Operation

In this work, we present a clear evidence, based on numerical simulations and experiments, that the polarization compensation due to trapped charge strongly influences the ON/ OFF ratio in Hf 0.5 Zr 0.5 O 2 (HZO)-based ferroelectric tunnel junctions (FTJs). Furthermore, we identify and explain compensation conditions that enable an optimal operation of FTJs. Our results provide both key physical insights and design guidelines for the operation of FTJs as multilevel synaptic devices.

physics.app-ph↗

arXiv2008

Optical Evidence for Mixed Phase Behavior in Manganites

Synchrotron infrared measurements were conducted over the range 100 to 8000 cm-1 on a self-doped LaxMnO3-d (x~~0.8) film. From these measurements we determined the conductivity, the effective number of free carriers, and the specific phonon modes as a function of frequency. While the metal-insulator transition temperature (TMI) and the magnetic ordering temperature (TC) approximately coincide, the free carrier density onset occurs at a significantly lower temperature (~~45 K below). This suggests that local distortions exist below TMI and TC which trap the eg conduction electrons. These regions with local distortions constitute an insulating phase which persists for temperatures significantly below TMI and TC. The initial large drop in resistivity is due to the enhanced magnetic ordering while further drops correspond to reductions in the insulating phase which increase the number of free carriers.

cond-mat.mtrl-sci↗

arXiv2007

Depressed Surface Magnetization in Thin La0.8MnO3 Films

A systematic study the magnetization in La0.8.MnO3 films of thickness varying from ultra-thin to bulk-like has been conducted. The study reveals suppression of the bulk magnetization for films up to at least 1600 A. In addition, the surface (top 50 A) of all films exhibits depressed magnetization as observed by x-ray magnetic circular dichroism (XMCD). The reduced surface magnetization is attributed to the coexistence of magnetic and nonmagnetic components of the same chemical composition.

cond-mat.str-el↗

arXiv2004

Stoner-Wohlfart model applied to bicrystal magnetoresistance hysteresis

We calculate numerically the magnetization direction as function of magnetic field in the Stoner-Wohlfart theory and are able to reproduce the shape of the low-field magnetoresistance hysteresis observed in manganite grain boundary junctions. Moreover, we show that it is necessary to include biaxial magnetocrystalline anisotropy to fully describe the grain boundary magnetoresistance in La$_{0.7}$Sr$_{0.3}$MnO$_3$/SrTiO$_3$ bicrystal tunnel junctions.

cond-mat.mtrl-sci↗