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We study electron transport in nanostructures patterned in bilayer graphene patches grown epitaxially on SiC as a function of doping, magnetic field, and temperature. Away from charge neutrality transport is only weakly modulated by changes in carrier concentration induced by a local side-gate. At low n-type doping close to charge neutrality, electron transport resembles that in exfoliated graphene nanoribbons and is well described by tunnelling of single electrons through a network of Coulomb-blockaded islands. Under the influence of an external magnetic field, Coulomb blockade resonances fluctuate around an average energy and the gap shrinks as a function of magnetic field. At charge neutrality, however, conduction is less insensitive to external magnetic fields. In this regime we also observe a stronger suppression of the conductance below T*, which we interpret as a sign of broken interlayer symmetry or strong fluctuations in the edge/potential disorder. (C) 2017 Elsevier Ltd. All rights reserved., Funding Agencies|Engineering and Physical Sciences Research Council [EP/L020963/1]; EU [696656 - GrapheneCore 1]

Epitaxial graphene has proven itself to be the best candidate for quantum electrical resistance standards due to its wide quantum Hall plateaus with exceptionally high breakdown currents. However one key underlying mechanism, a magnetic field dependent charge transfer process, is yet to be fully understood. Here we report measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to an almost linear increase in carrier density with magnetic field. This behaviour is strong evidence for field dependent charge transfer from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels we model the densities of donor states and predict the field dependence of charge transfer in excellent agreement with experimental results, thus providing a guide towards engineering epitaxial graphene for applications such as quantum metrology., Funding Agencies|UK EPSRC; Graphene Flagship [CNECT-ICT-604391]; EMRP project GraphOhm; AFRL grant [FA9550-15-C-0067]; LNCMI-CNRS; International Collaborative Energy Technology R&D Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP); Ministry of Trade, Industry & Energy, Republic of Korea [20148520011250]

Epitaxial graphene has proven itself to be the best candidate for quantum electrical resistance standards due to its wide quantum Hall plateaus with exceptionally high breakdown currents. However one key underlying mechanism, a magnetic field dependent charge transfer process, is yet to be fully understood. Here we report measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to an almost linear increase in carrier density with magnetic field. This behaviour is strong evidence for field dependent charge transfer from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels we model the densities of donor states and predict the field dependence of charge transfer in excellent agreement with experimental results, thus providing a guide towards engineering epitaxial graphene for applications such as quantum metrology., Funding Agencies|UK EPSRC; Graphene Flagship [CNECT-ICT-604391]; EMRP project GraphOhm; AFRL grant [FA9550-15-C-0067]; LNCMI-CNRS; International Collaborative Energy Technology R&D Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP); Ministry of Trade, Industry & Energy, Republic of Korea [20148520011250]

Epitaxial graphene has proven itself to be the best candidate for quantum electrical resistance standards due to its wide quantum Hall plateaus with exceptionally high breakdown currents. However one key underlying mechanism, a magnetic field dependent charge transfer process, is yet to be fully understood. Here we report measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to an almost linear increase in carrier density with magnetic field. This behaviour is strong evidence for field dependent charge transfer from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels we model the densities of donor states and predict the field dependence of charge transfer in excellent agreement with experimental results, thus providing a guide towards engineering epitaxial graphene for applications such as quantum metrology., Funding Agencies|UK EPSRC; Graphene Flagship [CNECT-ICT-604391]; EMRP project GraphOhm; AFRL grant [FA9550-15-C-0067]; LNCMI-CNRS; International Collaborative Energy Technology R&D Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP); Ministry of Trade, Industry & Energy, Republic of Korea [20148520011250]

Epitaxial graphene has proven itself to be the best candidate for quantum electrical resistance standards due to its wide quantum Hall plateaus with exceptionally high breakdown currents. However one key underlying mechanism, a magnetic field dependent charge transfer process, is yet to be fully understood. Here we report measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to an almost linear increase in carrier density with magnetic field. This behaviour is strong evidence for field dependent charge transfer from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels we model the densities of donor states and predict the field dependence of charge transfer in excellent agreement with experimental results, thus providing a guide towards engineering epitaxial graphene for applications such as quantum metrology., Funding Agencies|UK EPSRC; Graphene Flagship [CNECT-ICT-604391]; EMRP project GraphOhm; AFRL grant [FA9550-15-C-0067]; LNCMI-CNRS; International Collaborative Energy Technology R&D Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP); Ministry of Trade, Industry & Energy, Republic of Korea [20148520011250]

Epitaxial graphene has proven itself to be the best candidate for quantum electrical resistance standards due to its wide quantum Hall plateaus with exceptionally high breakdown currents. However one key underlying mechanism, a magnetic field dependent charge transfer process, is yet to be fully understood. Here we report measurements of the quantum Hall effect in epitaxial graphene showing the widest quantum Hall plateau observed to date extending over 50 T, attributed to an almost linear increase in carrier density with magnetic field. This behaviour is strong evidence for field dependent charge transfer from charge reservoirs with exceptionally high densities of states in close proximity to the graphene. Using a realistic framework of broadened Landau levels we model the densities of donor states and predict the field dependence of charge transfer in excellent agreement with experimental results, thus providing a guide towards engineering epitaxial graphene for applications such as quantum metrology., Funding Agencies|UK EPSRC; Graphene Flagship [CNECT-ICT-604391]; EMRP project GraphOhm; AFRL grant [FA9550-15-C-0067]; LNCMI-CNRS; International Collaborative Energy Technology R&D Program of the Korean Institute of Energy Technology Evaluation and Planning (KETEP); Ministry of Trade, Industry & Energy, Republic of Korea [20148520011250]

We demonstrate quantum Hall resistance measurements with metrological accuracy in a small cryogen-free system operating at a temperature of around 3.8 K and magnetic fields below 5 T. We use this system to investigate the optimisation of graphene/SiC devices for maximum breakdown current. In addition we report the first characterisation of a cryogen-free cryogenic current comparator which enables entirely cryogen-free primary resistance metrology.

We have demonstrated quantum Hall resistance measurements with metrological accuracy in a relatively easy to use and compact cryogen-free system operating at a temperature of around 3.8 K and magnetic field below 5 T. This advance in technology is due to the unique properties of epitaxial graphene on silicon carbide (SiC) which lifts the stringent requirements for quantum hall effect seen in conventional semiconductors. This paper presents the processes involved in fabrication and characterization of metrologically viable epitaxial graphene samples.

Experimental evidence from both spin-valve and quantum transport measurements points towards unexpectedly fast spin relaxation in graphene. We report magnetotransport studies of epitaxial graphene on SiC in a vector magnetic field showing that spin relaxation, detected using weak-localization analysis, is suppressed by an in-plane magnetic field B-parallel to, and thereby proving that it is caused at least in part by spinful scatterers. A nonmonotonic dependence of the effective decoherence rate on B-parallel to reveals the intricate role of the scatterers spin dynamics in forming the interference correction to the conductivity, an effect that has gone unnoticed in earlier weak localization studies., Funding Agencies|NSERC; CFI; Quantum Matter Institute (QMI); EC Graphene Flagship [CNECT-ICT-604391]; European Metrology Research Program (EMRP) project GraphOhm; ERC Synergy Grant Hetero2D; Deutsche Forschungsgemeinschaft [GRK 1621]; Linnaeus Centre for Quantum Engineering; Swedish Research Council; Knut and Alice Wallenberg Foundation; Swedish Foundation for Strategic Research (SSF); Chalmers Area of Advance NANO

We report a study of disorder effects on epitaxial graphene in the vicinity of the Dirac point by magnetotransport. Hall effect measurements show that the carrier density increases quadratically with temperature, in good agreement with theoretical predictions which take into account intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. We deduce disorder strengths in the range 10.2-31.2 meV, depending on the sample treatment. We investigate the scattering mechanisms and estimate the impurity density to be 3.0-9.1x10(10) cm(-2) for our samples. A scattering asymmetry for electrons and holes is observed and is consistent with theoretical calculations for graphene on SiC substrates. We also show that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations., Funding Agencies|U.K. EPSRC; NMS, E.U. Graphene Flagship [CNECT-ICT-604391]; EMRP Graph Ohm; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; China Scholarship Council

We report a study of disorder effects on epitaxial graphene in the vicinity of the Dirac point by magnetotransport. Hall effect measurements show that the carrier density increases quadratically with temperature, in good agreement with theoretical predictions which take into account intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. We deduce disorder strengths in the range 10.2-31.2 meV, depending on the sample treatment. We investigate the scattering mechanisms and estimate the impurity density to be 3.0-9.1x10(10) cm(-2) for our samples. A scattering asymmetry for electrons and holes is observed and is consistent with theoretical calculations for graphene on SiC substrates. We also show that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations., Funding Agencies|U.K. EPSRC; NMS, E.U. Graphene Flagship [CNECT-ICT-604391]; EMRP Graph Ohm; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; China Scholarship Council

We demonstrate quantum Hall resistance measurements with metrological accuracy in a small cryogen-free system operating at a temperature of around 3.8 K and magnetic fields below 5 T. Operating this system requires little experimental knowledge or laboratory infrastructure, thereby greatly advancing the proliferation of primary quantum standards for precision electrical metrology. This significant advance in technology has come about as a result of the unique properties of epitaxial graphene on SiC., Funding Agencies|NPL Proof-of-Concept fund; NMS Programme; European Union [604391]; EMRP Project GraphOhm

Experimental evidence from both spin-valve and quantum transport measurements points towards unexpectedly fast spin relaxation in graphene. We report magnetotransport studies of epitaxial graphene on SiC in a vector magnetic field showing that spin relaxation, detected using weak-localization analysis, is suppressed by an in-plane magnetic field B-parallel to, and thereby proving that it is caused at least in part by spinful scatterers. A nonmonotonic dependence of the effective decoherence rate on B-parallel to reveals the intricate role of the scatterers spin dynamics in forming the interference correction to the conductivity, an effect that has gone unnoticed in earlier weak localization studies., Funding Agencies|NSERC; CFI; Quantum Matter Institute (QMI); EC Graphene Flagship [CNECT-ICT-604391]; European Metrology Research Program (EMRP) project GraphOhm; ERC Synergy Grant Hetero2D; Deutsche Forschungsgemeinschaft [GRK 1621]; Linnaeus Centre for Quantum Engineering; Swedish Research Council; Knut and Alice Wallenberg Foundation; Swedish Foundation for Strategic Research (SSF); Chalmers Area of Advance NANO

We demonstrate quantum Hall resistance measurements with metrological accuracy in a small cryogen-free system operating at a temperature of around 3.8 K and magnetic fields below 5 T. Operating this system requires little experimental knowledge or laboratory infrastructure, thereby greatly advancing the proliferation of primary quantum standards for precision electrical metrology. This significant advance in technology has come about as a result of the unique properties of epitaxial graphene on SiC., Funding Agencies|NPL Proof-of-Concept fund; NMS Programme; European Union [604391]; EMRP Project GraphOhm

We report a study of disorder effects on epitaxial graphene in the vicinity of the Dirac point by magnetotransport. Hall effect measurements show that the carrier density increases quadratically with temperature, in good agreement with theoretical predictions which take into account intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. We deduce disorder strengths in the range 10.2-31.2 meV, depending on the sample treatment. We investigate the scattering mechanisms and estimate the impurity density to be 3.0-9.1x10(10) cm(-2) for our samples. A scattering asymmetry for electrons and holes is observed and is consistent with theoretical calculations for graphene on SiC substrates. We also show that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations., Funding Agencies|U.K. EPSRC; NMS, E.U. Graphene Flagship [CNECT-ICT-604391]; EMRP Graph Ohm; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; China Scholarship Council

Experimental evidence from both spin-valve and quantum transport measurements points towards unexpectedly fast spin relaxation in graphene. We report magnetotransport studies of epitaxial graphene on SiC in a vector magnetic field showing that spin relaxation, detected using weak-localization analysis, is suppressed by an in-plane magnetic field B-parallel to, and thereby proving that it is caused at least in part by spinful scatterers. A nonmonotonic dependence of the effective decoherence rate on B-parallel to reveals the intricate role of the scatterers spin dynamics in forming the interference correction to the conductivity, an effect that has gone unnoticed in earlier weak localization studies., Funding Agencies|NSERC; CFI; Quantum Matter Institute (QMI); EC Graphene Flagship [CNECT-ICT-604391]; European Metrology Research Program (EMRP) project GraphOhm; ERC Synergy Grant Hetero2D; Deutsche Forschungsgemeinschaft [GRK 1621]; Linnaeus Centre for Quantum Engineering; Swedish Research Council; Knut and Alice Wallenberg Foundation; Swedish Foundation for Strategic Research (SSF); Chalmers Area of Advance NANO

We demonstrate quantum Hall resistance measurements with metrological accuracy in a small cryogen-free system operating at a temperature of around 3.8 K and magnetic fields below 5 T. Operating this system requires little experimental knowledge or laboratory infrastructure, thereby greatly advancing the proliferation of primary quantum standards for precision electrical metrology. This significant advance in technology has come about as a result of the unique properties of epitaxial graphene on SiC., Funding Agencies|NPL Proof-of-Concept fund; NMS Programme; European Union [604391]; EMRP Project GraphOhm

We demonstrate quantum Hall resistance measurements with metrological accuracy in a small cryogen-free system operating at a temperature of around 3.8 K and magnetic fields below 5 T. Operating this system requires little experimental knowledge or laboratory infrastructure, thereby greatly advancing the proliferation of primary quantum standards for precision electrical metrology. This significant advance in technology has come about as a result of the unique properties of epitaxial graphene on SiC., Funding Agencies|NPL Proof-of-Concept fund; NMS Programme; European Union [604391]; EMRP Project GraphOhm

We demonstrate quantum Hall resistance measurements with metrological accuracy in a small cryogen-free system operating at a temperature of around 3.8 K and magnetic fields below 5 T. Operating this system requires little experimental knowledge or laboratory infrastructure, thereby greatly advancing the proliferation of primary quantum standards for precision electrical metrology. This significant advance in technology has come about as a result of the unique properties of epitaxial graphene on SiC., Funding Agencies|NPL Proof-of-Concept fund; NMS Programme; European Union [604391]; EMRP Project GraphOhm

Experimental evidence from both spin-valve and quantum transport measurements points towards unexpectedly fast spin relaxation in graphene. We report magnetotransport studies of epitaxial graphene on SiC in a vector magnetic field showing that spin relaxation, detected using weak-localization analysis, is suppressed by an in-plane magnetic field B-parallel to, and thereby proving that it is caused at least in part by spinful scatterers. A nonmonotonic dependence of the effective decoherence rate on B-parallel to reveals the intricate role of the scatterers spin dynamics in forming the interference correction to the conductivity, an effect that has gone unnoticed in earlier weak localization studies., Funding Agencies|NSERC; CFI; Quantum Matter Institute (QMI); EC Graphene Flagship [CNECT-ICT-604391]; European Metrology Research Program (EMRP) project GraphOhm; ERC Synergy Grant Hetero2D; Deutsche Forschungsgemeinschaft [GRK 1621]; Linnaeus Centre for Quantum Engineering; Swedish Research Council; Knut and Alice Wallenberg Foundation; Swedish Foundation for Strategic Research (SSF); Chalmers Area of Advance NANO

We report a study of disorder effects on epitaxial graphene in the vicinity of the Dirac point by magnetotransport. Hall effect measurements show that the carrier density increases quadratically with temperature, in good agreement with theoretical predictions which take into account intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. We deduce disorder strengths in the range 10.2-31.2 meV, depending on the sample treatment. We investigate the scattering mechanisms and estimate the impurity density to be 3.0-9.1x10(10) cm(-2) for our samples. A scattering asymmetry for electrons and holes is observed and is consistent with theoretical calculations for graphene on SiC substrates. We also show that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations., Funding Agencies|U.K. EPSRC; NMS, E.U. Graphene Flagship [CNECT-ICT-604391]; EMRP Graph Ohm; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; China Scholarship Council

Experimental evidence from both spin-valve and quantum transport measurements points towards unexpectedly fast spin relaxation in graphene. We report magnetotransport studies of epitaxial graphene on SiC in a vector magnetic field showing that spin relaxation, detected using weak-localization analysis, is suppressed by an in-plane magnetic field B-parallel to, and thereby proving that it is caused at least in part by spinful scatterers. A nonmonotonic dependence of the effective decoherence rate on B-parallel to reveals the intricate role of the scatterers spin dynamics in forming the interference correction to the conductivity, an effect that has gone unnoticed in earlier weak localization studies., Funding Agencies|NSERC; CFI; Quantum Matter Institute (QMI); EC Graphene Flagship [CNECT-ICT-604391]; European Metrology Research Program (EMRP) project GraphOhm; ERC Synergy Grant Hetero2D; Deutsche Forschungsgemeinschaft [GRK 1621]; Linnaeus Centre for Quantum Engineering; Swedish Research Council; Knut and Alice Wallenberg Foundation; Swedish Foundation for Strategic Research (SSF); Chalmers Area of Advance NANO

We report a study of disorder effects on epitaxial graphene in the vicinity of the Dirac point by magnetotransport. Hall effect measurements show that the carrier density increases quadratically with temperature, in good agreement with theoretical predictions which take into account intrinsic thermal excitation combined with electron-hole puddles induced by charged impurities. We deduce disorder strengths in the range 10.2-31.2 meV, depending on the sample treatment. We investigate the scattering mechanisms and estimate the impurity density to be 3.0-9.1x10(10) cm(-2) for our samples. A scattering asymmetry for electrons and holes is observed and is consistent with theoretical calculations for graphene on SiC substrates. We also show that the minimum conductivity increases with increasing disorder strength, in good agreement with quantum-mechanical numerical calculations., Funding Agencies|U.K. EPSRC; NMS, E.U. Graphene Flagship [CNECT-ICT-604391]; EMRP Graph Ohm; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Alice Wallenberg Foundation; Chalmers AoA Nano; China Scholarship Council

We demonstrate reversible carrier density control across the Dirac point (Delta n similar to 10(13) cm(-2)) in epitaxial graphene on SiC (SiC/G) via high electrostatic potential gating with ions produced by corona discharge. The method is attractive for applications where graphene with a fixed carrier density is needed, such as quantum metrology, and more generally as a simple method of gating 2DEGs formed at semiconductor interfaces and in topological insulators., Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Allice Wallenberg Foundation; Chalmers AoA Nano; NMS (UK); EMRP project GraphOhm; EMRP within EURAMET; European Union

We demonstrate reversible carrier density control across the Dirac point (Delta n similar to 10(13) cm(-2)) in epitaxial graphene on SiC (SiC/G) via high electrostatic potential gating with ions produced by corona discharge. The method is attractive for applications where graphene with a fixed carrier density is needed, such as quantum metrology, and more generally as a simple method of gating 2DEGs formed at semiconductor interfaces and in topological insulators., Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Allice Wallenberg Foundation; Chalmers AoA Nano; NMS (UK); EMRP project GraphOhm; EMRP within EURAMET; European Union

We demonstrate reversible carrier density control across the Dirac point (Delta n similar to 10(13) cm(-2)) in epitaxial graphene on SiC (SiC/G) via high electrostatic potential gating with ions produced by corona discharge. The method is attractive for applications where graphene with a fixed carrier density is needed, such as quantum metrology, and more generally as a simple method of gating 2DEGs formed at semiconductor interfaces and in topological insulators., Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Allice Wallenberg Foundation; Chalmers AoA Nano; NMS (UK); EMRP project GraphOhm; EMRP within EURAMET; European Union

We demonstrate reversible carrier density control across the Dirac point (Delta n similar to 10(13) cm(-2)) in epitaxial graphene on SiC (SiC/G) via high electrostatic potential gating with ions produced by corona discharge. The method is attractive for applications where graphene with a fixed carrier density is needed, such as quantum metrology, and more generally as a simple method of gating 2DEGs formed at semiconductor interfaces and in topological insulators., Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Allice Wallenberg Foundation; Chalmers AoA Nano; NMS (UK); EMRP project GraphOhm; EMRP within EURAMET; European Union

We demonstrate reversible carrier density control across the Dirac point (Delta n similar to 10(13) cm(-2)) in epitaxial graphene on SiC (SiC/G) via high electrostatic potential gating with ions produced by corona discharge. The method is attractive for applications where graphene with a fixed carrier density is needed, such as quantum metrology, and more generally as a simple method of gating 2DEGs formed at semiconductor interfaces and in topological insulators., Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Allice Wallenberg Foundation; Chalmers AoA Nano; NMS (UK); EMRP project GraphOhm; EMRP within EURAMET; European Union

We demonstrate reversible carrier density control across the Dirac point (Delta n similar to 10(13) cm(-2)) in epitaxial graphene on SiC (SiC/G) via high electrostatic potential gating with ions produced by corona discharge. The method is attractive for applications where graphene with a fixed carrier density is needed, such as quantum metrology, and more generally as a simple method of gating 2DEGs formed at semiconductor interfaces and in topological insulators., Funding Agencies|Graphene Flagship [CNECT-ICT-604391]; Swedish Foundation for Strategic Research (SSF); Linnaeus Centre for Quantum Engineering; Knut and Allice Wallenberg Foundation; Chalmers AoA Nano; NMS (UK); EMRP project GraphOhm; EMRP within EURAMET; European Union

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by similar to 40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T-e(4) at low temperatures and depend weakly on carrier density proportional to n(-1/2), evidence for enhancement of the energy loss rate due to disorder in CVD samples., Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU

We report the phase space defined by the quantum Hall effect breakdown in polymer gated epitaxial graphene on SiC (SiC/G) as a function of temperature, current, carrier density, and magnetic fields up to 30 T. At 2 K, breakdown currents (Ic) almost 2 orders of magnitude greater than in GaAs devices are observed. The phase boundary of the dissipationless state (ρxx=0) shows a [1-(T/Tc)2] dependence and persists up to Tc>45 K at 29 T. With magnetic field Ic was found to increase ∝B3/2 and Tc∝B2. As the Fermi energy approaches the Dirac point, the ν=2 quantized Hall plateau appears continuously from fields as low as 1 T up to at least 19 T due to a strong magnetic field dependence of the carrier density., Funding Agencies|EuroMagNET II||EU|228043|U.K. EPSRC||EU Project ConceptGraphene||NPL Strategic Research Programme

We report the phase space defined by the quantum Hall effect breakdown in polymer gated epitaxial graphene on SiC (SiC/G) as a function of temperature, current, carrier density, and magnetic fields up to 30 T. At 2 K, breakdown currents (Ic) almost 2 orders of magnitude greater than in GaAs devices are observed. The phase boundary of the dissipationless state (ρxx=0) shows a [1-(T/Tc)2] dependence and persists up to Tc>45 K at 29 T. With magnetic field Ic was found to increase ∝B3/2 and Tc∝B2. As the Fermi energy approaches the Dirac point, the ν=2 quantized Hall plateau appears continuously from fields as low as 1 T up to at least 19 T due to a strong magnetic field dependence of the carrier density., Funding Agencies|EuroMagNET II||EU|228043|U.K. EPSRC||EU Project ConceptGraphene||NPL Strategic Research Programme

We have performed low-temperature magnetotransport measurements on monolayer epitaxial graphene under microwave radiation and extracted the radiation-induced effective temperatures, energy relaxation, and the dephasing times. We established that the response of the graphene sample is entirely bolometric at least up to 170 GHz. Dynamic dephasing, i.e., the time-reversal symmetry breaking effect of the ac electromagnetic field rather than mediated by heating, may become significant in the terahertz frequency range and in samples with longer phase coherence time., Funding Agencies|Swedish Research Council||Foundation for Strategic Research||EPSRC|EP/K016822/1|EU FP7 STREP ConceptGraphene

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by similar to 40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T-e(4) at low temperatures and depend weakly on carrier density proportional to n(-1/2), evidence for enhancement of the energy loss rate due to disorder in CVD samples., Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU

We report the phase space defined by the quantum Hall effect breakdown in polymer gated epitaxial graphene on SiC (SiC/G) as a function of temperature, current, carrier density, and magnetic fields up to 30 T. At 2 K, breakdown currents (Ic) almost 2 orders of magnitude greater than in GaAs devices are observed. The phase boundary of the dissipationless state (ρxx=0) shows a [1-(T/Tc)2] dependence and persists up to Tc>45 K at 29 T. With magnetic field Ic was found to increase ∝B3/2 and Tc∝B2. As the Fermi energy approaches the Dirac point, the ν=2 quantized Hall plateau appears continuously from fields as low as 1 T up to at least 19 T due to a strong magnetic field dependence of the carrier density., Funding Agencies|EuroMagNET II||EU|228043|U.K. EPSRC||EU Project ConceptGraphene||NPL Strategic Research Programme

We have performed low-temperature magnetotransport measurements on monolayer epitaxial graphene under microwave radiation and extracted the radiation-induced effective temperatures, energy relaxation, and the dephasing times. We established that the response of the graphene sample is entirely bolometric at least up to 170 GHz. Dynamic dephasing, i.e., the time-reversal symmetry breaking effect of the ac electromagnetic field rather than mediated by heating, may become significant in the terahertz frequency range and in samples with longer phase coherence time., Funding Agencies|Swedish Research Council||Foundation for Strategic Research||EPSRC|EP/K016822/1|EU FP7 STREP ConceptGraphene

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by similar to 40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T-e(4) at low temperatures and depend weakly on carrier density proportional to n(-1/2), evidence for enhancement of the energy loss rate due to disorder in CVD samples., Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU

We report the phase space defined by the quantum Hall effect breakdown in polymer gated epitaxial graphene on SiC (SiC/G) as a function of temperature, current, carrier density, and magnetic fields up to 30 T. At 2 K, breakdown currents (Ic) almost 2 orders of magnitude greater than in GaAs devices are observed. The phase boundary of the dissipationless state (ρxx=0) shows a [1-(T/Tc)2] dependence and persists up to Tc>45 K at 29 T. With magnetic field Ic was found to increase ∝B3/2 and Tc∝B2. As the Fermi energy approaches the Dirac point, the ν=2 quantized Hall plateau appears continuously from fields as low as 1 T up to at least 19 T due to a strong magnetic field dependence of the carrier density., Funding Agencies|EuroMagNET II||EU|228043|U.K. EPSRC||EU Project ConceptGraphene||NPL Strategic Research Programme

We have performed low-temperature magnetotransport measurements on monolayer epitaxial graphene under microwave radiation and extracted the radiation-induced effective temperatures, energy relaxation, and the dephasing times. We established that the response of the graphene sample is entirely bolometric at least up to 170 GHz. Dynamic dephasing, i.e., the time-reversal symmetry breaking effect of the ac electromagnetic field rather than mediated by heating, may become significant in the terahertz frequency range and in samples with longer phase coherence time., Funding Agencies|Swedish Research Council||Foundation for Strategic Research||EPSRC|EP/K016822/1|EU FP7 STREP ConceptGraphene

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by similar to 40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T-e(4) at low temperatures and depend weakly on carrier density proportional to n(-1/2), evidence for enhancement of the energy loss rate due to disorder in CVD samples., Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by similar to 40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T-e(4) at low temperatures and depend weakly on carrier density proportional to n(-1/2), evidence for enhancement of the energy loss rate due to disorder in CVD samples., Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU

We have performed low-temperature magnetotransport measurements on monolayer epitaxial graphene under microwave radiation and extracted the radiation-induced effective temperatures, energy relaxation, and the dephasing times. We established that the response of the graphene sample is entirely bolometric at least up to 170 GHz. Dynamic dephasing, i.e., the time-reversal symmetry breaking effect of the ac electromagnetic field rather than mediated by heating, may become significant in the terahertz frequency range and in samples with longer phase coherence time., Funding Agencies|Swedish Research Council||Foundation for Strategic Research||EPSRC|EP/K016822/1|EU FP7 STREP ConceptGraphene

We have performed low-temperature magnetotransport measurements on monolayer epitaxial graphene under microwave radiation and extracted the radiation-induced effective temperatures, energy relaxation, and the dephasing times. We established that the response of the graphene sample is entirely bolometric at least up to 170 GHz. Dynamic dephasing, i.e., the time-reversal symmetry breaking effect of the ac electromagnetic field rather than mediated by heating, may become significant in the terahertz frequency range and in samples with longer phase coherence time., Funding Agencies|Swedish Research Council||Foundation for Strategic Research||EPSRC|EP/K016822/1|EU FP7 STREP ConceptGraphene

Energy loss rates for hot carriers in graphene have been measured using graphene produced by epitaxial growth on SiC, exfoliation, and chemical vapor deposition (CVD). It is shown that the temperature dependence of the energy loss rates measured with high-field damped Shubnikov-de Haas oscillations and the temperature dependence of the weak localization peak close to zero field correlate well, with the high-field measurements understating the energy loss rates by similar to 40% compared to the low-field results. The energy loss rates for all graphene samples follow a universal scaling of T-e(4) at low temperatures and depend weakly on carrier density proportional to n(-1/2), evidence for enhancement of the energy loss rate due to disorder in CVD samples., Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU

Weak localization in graphene is studied as a function of carrier density in the range from 1 x 10(11) cm(-2) to 1.43 x 10(13) cm(-2) using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyze the dependence of the scattering lengths L-phi, L-i, and L-* on carrier density. We find no significant carrier dependence for L-phi, a weak decrease for L-i with increasing carrier density just beyond a large standard error, and a n(-1/4) dependence for L-*. We demonstrate that currents as low as 0.01 nA are required in smaller devices to avoid hot-electron artifacts in measurements of the quantum corrections to conductivity. DOI: 10.1103/PhysRevB.86.235441, Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU FP7 STREP ConceptGraphene

Weak localization in graphene is studied as a function of carrier density in the range from 1 x 10(11) cm(-2) to 1.43 x 10(13) cm(-2) using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyze the dependence of the scattering lengths L-phi, L-i, and L-* on carrier density. We find no significant carrier dependence for L-phi, a weak decrease for L-i with increasing carrier density just beyond a large standard error, and a n(-1/4) dependence for L-*. We demonstrate that currents as low as 0.01 nA are required in smaller devices to avoid hot-electron artifacts in measurements of the quantum corrections to conductivity. DOI: 10.1103/PhysRevB.86.235441, Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU FP7 STREP ConceptGraphene

Weak localization in graphene is studied as a function of carrier density in the range from 1 x 10(11) cm(-2) to 1.43 x 10(13) cm(-2) using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyze the dependence of the scattering lengths L-phi, L-i, and L-* on carrier density. We find no significant carrier dependence for L-phi, a weak decrease for L-i with increasing carrier density just beyond a large standard error, and a n(-1/4) dependence for L-*. We demonstrate that currents as low as 0.01 nA are required in smaller devices to avoid hot-electron artifacts in measurements of the quantum corrections to conductivity. DOI: 10.1103/PhysRevB.86.235441, Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU FP7 STREP ConceptGraphene

Weak localization in graphene is studied as a function of carrier density in the range from 1 x 10(11) cm(-2) to 1.43 x 10(13) cm(-2) using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyze the dependence of the scattering lengths L-phi, L-i, and L-* on carrier density. We find no significant carrier dependence for L-phi, a weak decrease for L-i with increasing carrier density just beyond a large standard error, and a n(-1/4) dependence for L-*. We demonstrate that currents as low as 0.01 nA are required in smaller devices to avoid hot-electron artifacts in measurements of the quantum corrections to conductivity. DOI: 10.1103/PhysRevB.86.235441, Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU FP7 STREP ConceptGraphene

Weak localization in graphene is studied as a function of carrier density in the range from 1 x 10(11) cm(-2) to 1.43 x 10(13) cm(-2) using devices produced by epitaxial growth onto SiC and CVD growth on thin metal film. The magnetic field dependent weak localization is found to be well fitted by theory, which is then used to analyze the dependence of the scattering lengths L-phi, L-i, and L-* on carrier density. We find no significant carrier dependence for L-phi, a weak decrease for L-i with increasing carrier density just beyond a large standard error, and a n(-1/4) dependence for L-*. We demonstrate that currents as low as 0.01 nA are required in smaller devices to avoid hot-electron artifacts in measurements of the quantum corrections to conductivity. DOI: 10.1103/PhysRevB.86.235441, Funding Agencies|UK EPSRC||Swedish Research Council||Foundation for Strategic Research||UK National Measurement Office||EU FP7 STREP ConceptGraphene