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It has been reported that graphite hosts room temperature superconductivity. Here we provide new results that confirm these claims on different samples of highly oriented pyrolytic graphite (HOPG) and commercial flexible graphite gaskets…

We have identified ferromagnetic- and superconducting-like magnetization hysteresis loops in highly oriented pyrolytic graphite samples below and above room temperature. We also found that both behaviors are very sensitive to…

Strongly Correlated Electrons · Physics 2007-05-23 Y. Kopelevich , P. Esquinazi , J. H. S. Torres , S. Moehlecke

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

Transport properties of a few hundreds of nanometers thick (in the graphene plane direction) lamellae of highly oriented pyrolytic graphite (HOPG) have been investigated. Current-Voltage characteristics as well as the temperature dependence…

Superconductivity · Physics 2013-02-25 A. Ballestar , J. Barzola-Quiquia , P. Esquinazi

We report the observation of proximity effect in measurements performed on highly oriented pyrolitic graphite (HOPG) samples when electrical current is injected through the superconducting electrodes placed on the sample surface few…

In the last 43 years several hints were reported suggesting the existence of granular superconductivity above room temperature in different graphite-based systems. In this paper some of the results are reviewed, giving special attention to…

This article reviews recent results of magnetotransport and magnetization measurements performed on highly oriented pyrolitic graphite (HOPG) and single crystalline Kish graphite samples. Both metal-insulator and insulator-metal transitions…

Strongly Correlated Electrons · Physics 2007-05-23 Y. Kopelevich , P. Esquinazi , J. H. S. Torres , R. R. da Silva , H. Kempa , F. Mrowka , R. Ocana

Trying to dope graphite flakes we found that the magnetization of pure, several tens of micrometers grain size graphite powder and after a simple treatment with pure water shows clear and reproducible granular superconducting behavior with…

Superconductivity · Physics 2013-07-09 T. Scheike , W. Böhlmann , P. Esquinazi , J. Barzola-Quiquia , A. Ballestar , A. Setzer

Room temperature superconductivity under normal conditions has been a major challenge of physics and material science since its very discovery. Here we report the global room-temperature superconductivity observed in cleaved highly oriented…

We have observed possible superconductivity using standard resistance vs. temperature techniques in phosphorous ion implanted Highly Oriented Pyrolytic Graphite. The onset appears to be above 100 K and quenching by an applied magnetic field…

Superconductivity · Physics 2015-05-28 Grover Larkins , Yuriy Vlasov

High resolution magnetoresistance data in highly oriented pyrolytic graphite thin samples manifest non-homogenous superconductivity with critical temperature $T_c \sim 25 $K. These data exhibit: i) hysteretic loops of resistance versus…

Superconductivity with transition temperature $T_c=1.7$ K has been reported in bilayer graphene [1,2]. The main factors, which may shed light on the mechanism of the formation of this superconductivity, are the following. Superconductivity…

Superconductivity · Physics 2018-06-22 G. E. Volovik

The transport properties of highly oriented pyrolitic graphite (HOPG) and polycrystal graphite have been studied. The electric conductivity of HOPG is several times larger than that of the polycrystal graphite. Along with the large…

Materials Science · Physics 2008-01-23 Zhiming Wang , Feng Xu , Chao Lu , He Zhang , Qingyu Xu , Jinan Zhu

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 report transport and magnetization measurements on graphitic materials that have been hydrogenated after being treated with octane. The temperature-dependent electrical resistivity shows anomalies manifested as re-entrant insulator-metal…

Superconductivity · Physics 2020-05-13 Nadina Gheorghiu , Charles R. Ebbing , Timothy J. Haugan

Surface superconductivity in rhombohedral graphite is a robust phenomenon which can exist even when higher order hoppings between the layers lift the topological protection of the surface flat band and introduce a quadratic dispersion of…

Superconductivity · Physics 2013-05-13 N. B. Kopnin , M. Ijäs , A. Harju , T. T. Heikkilä

It has been claimed that graphite hosts superconductivity at room temperature, although all efforts to isolate it have been vain. Here we report a separation method that uses magnetic field gradients to sort the superconducting from normal…

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

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 transport properties of transmission electron microscope (TEM) lamellae obtained from a pyrolytic graphite sample of grade B (SPI-II) with electrical contacts at the edges of the graphene layers. The temperature,…

Superconductivity · Physics 2015-06-23 Ana Ballestar , Pablo Esquinazi , Winfried Böhlmann
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