Colloquium: Graphene spectroscopy

Spectroscopic studies of electronic phenomena in graphene are reviewed. A variety of methods and techniques are surveyed, from quasiparticle spectroscopies (tunneling, photoemission) to methods probing density and current response (infrared optics, Raman) to scanning probe nanoscopy and ultrafast pump-probe experiments. Vast complimentary information derived from these investigations is shown to highlight unusual properties of Dirac quasiparticles and many-body interaction effects in the physics of graphene.Comment: 36 pages, 16 figure

Toxicology of chemically modified graphene-based materials for medical application.

This review article aims to provide an overview of chemically modified graphene, and graphene oxide (GO), and their impact on toxicology when present in biological systems. Graphene is one of the most promising nanomaterials due to unique physicochemical properties including enhanced optical, thermal, and electrically conductive behavior in addition to mechanical strength and high surface-to-volume ratio. Graphene-based nanomaterials have received much attention over the last 5 years in the biomedical field ranging from their use as polymeric conduits for nerve regeneration, carriers for targeted drug delivery and in the treatment of cancer via photo-thermal therapy. Both in vitro and in vivo biological studies of graphene-based nanomaterials help understand their relative toxicity and biocompatibility when used for biomedical applications. Several studies investigating important material properties such as surface charge, concentration, shape, size, structural defects, and chemical functional groups relate to their safety profile and influence cyto- and geno-toxicology. In this review, we highlight the most recent studies of graphene-based nanomaterials and outline their unique properties, which determine their interactions under a range of environmental conditions. The advent of graphene technology has led to many promising new opportunities for future applications in the field of electronics, biotechnology, and nanomedicine to aid in the diagnosis and treatment of a variety of debilitating diseases

Low pressure CVD of graphene on Cu thin film and reliable proximity graphene transfer for electronic applications

Graphene is a two dimensional monolayer composed of carbon atoms tightly packed into a hexagonal lattice. This single sheet sparked a great deal of interest among the research community due to its extraordinary properties which make it attractive for a wide range of applications, particularly in the micro electronics field. Currently, chemical vapor deposition (CVD) on copper foils is considered as the most promising route to synthesize graphene in terms of structural quality, thickness, uniformity and scalability [1]. However, one of the key limitations to the development of graphene-based devices emerges from the additional step required to transfer graphene from Cu foils onto specific substrates, typically dielectric materials [2, 3]. This transfer step is known to cause adverse effects on graphene quality and hinders drastically its processability. The transfer step can be circumvented by growing graphene on copper thin film pre-deposited on insulating substrates and by subsequently using this film as a sacrificial layer [4, 5]. [1] X. Li et al., Science, Vol. 324, no. 5932, pp. 1312–1314, 2009. [2] Y. Lee et al., Nano Letters, Vol. 10, no. 2, pp. 490–493, 2010. [3] R. Shi et al., Applied Physics Letters, vol. 102, no. 11, pp. 113102, 2013. [4] C.-Y. Su et al., Nano Letters, vol. 11, no. 9, pp. 3612-3616, 2011. [5] A. Ismach et al., Nano Letters, vol. 10, no. 5, pp. 1542-1548, 2010

Two-Dimensional Magnetic Tunnel Junctions: Insights from first-principles

Two-dimensional materials are promising candidates for use as tunnel barrier in atomically thin magnetic tunnel junctions (MTJs) [1]. High magneto resistance ratios have been predicted theoretically and recent progress in large scale manufacturing of these materials has paved the way to their integrations in functional devices. Yet, the experimental results available so far vary greatly depending on the integration pathways. Seeking for increased performances, it has been shown lately that direct CVD growth of tunnel barriers improves significantly the quality of the ferromagnet-2D materials interfaces [2-4]. Following these recent developments, new phenomena such as the bias induced reversal of the magneto resistance were reported [5]. Here, we show that first-principles calculations can provide direct insights into the close relation that links the interface morphology to its magneto resistive behaviour. In particular, we reports on the origin of TMR reversal in h-BN based MTJs with cobalt electrodes [5]. References [1] M. Piquemal-Banci et al., J. Phys. D. Appl. Phys. (2017), 50, 203002 [2] S. Caneva et al., Nano Lett. (2016), 16, 1250. [3] M.-B. Martin et al., Appl. Phys. Lett. (2015), 107, 012408. [4] S. Caneva et al., ACS Appl. Mater. Interfaces (2017), 9, 29973. [5] M. Piquemal-Banci et al., ACS Nano, (2018) to be published