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We have developed a unique micromechanical method to extract extremely thin graphite samples. Graphite crystallites with thicknesses ranging from 10 - 100 nm and lateral size $\sim$ 2 $\mu$m are extracted from bulk. Mesoscopic graphite…

Mesoscale and Nanoscale Physics · Physics 2009-11-10 Yuanbo Zhang , Joshua P. Small , William V. Pontius , Philip Kim

This work deals with the intrinsic and extrinsic properties of the graphene layers inside the graphite structure, in particular the influence of defects and interfaces. We discuss the evidence for ballistic transport found in mesoscopic…

Materials Science · Physics 2011-10-13 J. Barzola-Quiquia , A. Ballestar , S. Dusari , P. Esquinazi

The carrier density in tens of nanometers thick graphite samples (multi-layer-graphene, MLG) has been modified by applying a gate voltage ($V_g$) perpendicular to the graphene planes. Surface potential microscopy shows inhomogeneities in…

Superconductivity · Physics 2014-02-04 A. Ballestar , P. Esquinazi , J. Barzola-Quiquia , S. Dusari , F. Bern , R. R. da Silva , Y. Kopelevich

We have studied the magnetotransport of conical and disk-shaped nanocarbon particles in magnetic fields $\left|B\right|\leq9\:\mathrm{T}$ at temperatures $2\leq T\leq300\:\mathrm{K}$ to characterize electron scattering in a three…

Mesoscale and Nanoscale Physics · Physics 2014-07-28 Jozef Černák , Geir Helgesen , Fredrik Sydow Hage , Jozef Kováč

We have measured the temperature and magnetic field dependence of the Hall coefficient ($R_{\rm H}$) in three, several micrometer long multigraphene samples of thickness between $\sim 9~$to $\sim 30$~nm in the temperature range 0.1 to 200~K…

Superconductivity · Physics 2014-11-07 P. Esquinazi , J. Krüger , J. Barzola-Quiquia , R. Schönemann , T. Herrmannsdörfer , N. García

We present a study of the magnetoresistance of highly oriented pyrolytic graphite (HOPG) as a function of the sample size. Our results show unequivocally that the magnetoresistance reduces with the sample size even for samples of hundreds…

Mesoscale and Nanoscale Physics · Physics 2015-05-13 J. C. González , M. Muñoz , N. García , J. Barzola-Quiquia , D. Spoddig , K. Schindler , P. Esquinazi

We have measured the magnetic field and temperature dependence of the resistivity of several micrometers long and heterogeneously thick graphite sample. The magnetoresistance results for fields applied nearly parallel to the graphene planes…

Strongly Correlated Electrons · Physics 2009-07-17 J. Barzola-Quiquia , P. Esquinazi

We have studied the magnetoresistance (MR) of thin highly oriented pyrolytic graphite mesoscopic samples without and with micro-constrictions of different widths between the voltage electrodes. The MR for fields parallel to the c-axis shows…

Superconductivity · Physics 2011-07-07 S. Dusari , J. Barzola-Quiquia And P. Esquinazi

In spite of 40 years of experimental studies and several theoretical proposals, an overall interpretation of the complex behavior of the magnetoresistance (MR) of multilayer graphene, i.e. graphite, at high fields ($B \lesssim 70~$T) and in…

Using a linear array of voltage electrodes with a separation of several micrometers on a $20 $nm thick and 30 $\mu$m long multigraphene sample we show that the measured resistance does not follow the usual length dependence according to…

Materials Science · Physics 2015-06-03 P. Esquinazi , J. Barzola-Quiquia , S. Dusari , N. García

Magic-angle twisted bilayer graphene is a tunable material with remarkably flat energy bands near the Fermi level, leading to fascinating transport properties and correlated states at low temperatures. However, grown pristine samples of…

Mesoscale and Nanoscale Physics · Physics 2024-03-29 Aleksander Sanjuan Ciepielewski , Jakub Tworzydło , Timo Hyart , Alexander Lau

We investigated the influence of thickness reduction on the transport properties of graphite microflakes. Using oxygen plasma etching we decreased the thickness of highly oriented pyrolytic graphite (HOPG) microflakes from $\sim 100$~nm to…

The electrical, in-plane resistance as a function of temperature $R(T)$ of bulk and mesoscopic thin graphite flakes obtained from the same batch was investigated. Samples thicker than $\sim 30$ nm show metalliclike contribution in a…

Investigations of the magnetic properties of graphenes prepared by different methods reveal that dominant ferromagnetic interactions coexist along with antiferromagnetic interactions in all the samples. Thus, all the graphene samples…

Chemical Physics · Physics 2009-04-20 H. S. S. Ramakrishna Matte , K. S. Subrahmanyam , C. N. R. Rao

Understanding magnetoresistance, the change in electrical resistance upon an external magnetic field, at the atomic level is of great interest both fundamentally and technologically. Graphene and other two-dimensional layered materials…

Thermal conduction was explored and discussed through a combined theoretical and simulation approach in this work. The thermal conductivity k of polycrystalline graphene was calculated by molecular dynamics simulations based on a hexagonal…

Materials Science · Physics 2014-06-05 Yanlei Wang , Zhigong Song , Zhiping Xu

Basal plane resistivity of expanded graphite was studied under simultaneous influence of hydrostatic pressure up to 1.8 GPa and magnetic field 0.8 T in the 77-300 K temperature region. Magnetic field induces negative magnetoresistance in…

Materials Science · Physics 2014-06-17 V. V. Slyusarev , P. I. Polyakov

The intrinsic values of the carriers mobility and density of the graphene layers inside graphite, the well known structure built on these layers in the Bernal stacking configuration, are not well known mainly because most of the research…

Materials Science · Physics 2015-05-20 S. Dusari , J. Barzola-Quiquia , P. Esquinazi , N. García

Temperature and field dependent measurements of the electrical resistance of different natural graphite samples, suggest the existence of superconductivity at room temperature in some regions of the samples. To verify whether…

Superconductivity · Physics 2018-02-02 Markus Stiller , Pablo D. Esquinazi , Jose Barzola-Quiquia , Christian E. Precker

We review experimental results, from transport to magnetization measurements, on different graphite samples, from bulk oriented graphite, thin graphite films to transmission electron microscope lamellae, that indicate the existence of…

Superconductivity · Physics 2013-12-17 Pablo Esquinazi
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