← Back to Search
Spin Transport In Graphene-hBN Heterostructures In Inverted Non-local Spin Valve Devices
M. Drögeler, C. Stampfer, T. Schäpers
Published 2017 · Materials Science
Download PDFAnalyze on Scholarcy
In this thesis a novel fabrication technique for graphene non-local spin valves is presented. This technique allows high charge carrier mobilities of 20,000cm2/(Vs), spin diffusion length of more than 30 μm and spin lifetimes of more than 12ns at room temperature. In contrast to previous studies the spin lifetime is a factor of six larger. Here, the Co/MgO electrodes are fabricated first on a Si/SiO2 substrate and subsequently an exfoliated graphene flake is transferred on top of the electrodes using hexagonal boron nitride (hBN). This may lead to a more homogeneous interface compared to old fabrication methods where electrodes were grown on the inert graphene surface. First, we investigate the homogeneity of the MgO layer by conductive scanning force microscopy prior to the graphene deposition. We find that the layer is homogeneous but exhibits conducting pinholes which lower the spin injection and detection efficiency. Moreover, we investigate the spatial variation of doping and strain of the graphene flake by confocal Raman spectroscopy. We find that some regions of the device are quasi suspended between the electrodes and some are in contact to the substrate which dopes the graphene and induces uniaxial strain in the graphene flake. However, the spin transport properties are not influenced by these variations. On the other hand, we observe that the spin transport properties are deteriorated if small hBN flakes are used as solvents and dissolved polymers can get in contact to the graphene flake. Additionally, we find that the charge carrier density dependence of the spin lifetime behaves differently at low temperatures for single and bilayer graphene. While there is no change for single layer in comparison to room temperature there is an enhanced spin dephasing near the charge neutrality point for bilayer graphene. This observation shines new light on the underlying spin dephasing mechanism in graphene. Additionally, the new fabrication technique was applied to chemically synthesized graphene. Despite some difficulties in the fabrication process it shows similar spin transport properties as exfoliated graphene which is important for technological applications and mass fabrication. Finally, simulations of the device structures demonstrate the effects of sample inhomogeneities on the spin transport properties. We show that regions with an enhanced spin dephasing always influence the measurements even if these regions are only adjacent to the actually measured one. This is important for future electrode design and employed materials.
This paper references
Electronic spin transport in bilayer and single layer graphene
Tsung-Yeh Yang (2011)
Coupling graphene mechanical resonators to superconducting microwave cavities.
P. Weber (2014)
Giant tunnelling magnetoresistance at room temperature with MgO (100) tunnel barriers
S. Parkin (2004)
Raman measurements of thermal transport in suspended monolayer graphene of variable sizes in vacuum and gaseous environments.
Shanshan Chen (2011)
Tunneling path toward spintronics
G. Miao (2011)
Long-Lived Hole Spin/Valley Polarization Probed by Kerr Rotation in Monolayer WSe2.
Xinlin Song (2016)
Unconventional quantum Hall effect and Berry’s phase of 2π in bilayer graphene
K. Novoselov (2006)
Graphene as an electronic membrane
E. Kim (2008)
Città DI Torino (1824)
Coupling of electronic charge and spin at a ferromagnetic-paramagnetic metal interface.
Spin relaxation of conduction electrons in noncentrosymmetric semiconductors
M. Dyakonov (1972)
How to Define and Calculate the Degree of Spin Polarization in Ferromagnets
I. Mazin (1999)
Experimental determination of anisotropy and demagnetizing factors of single Co nanowires by magnetoresistance measurements
M. Brands (2005)
Spin Lifetimes Exceeding 12 ns in Graphene Nonlocal Spin Valve Devices.
M. Drögeler (2016)
What are “ A ” and “ B ” ?
Band Structure of Graphite
R. P. (2011)
Landau-level splitting in graphene in high magnetic fields.
Y. Zhang (2006)
Semiconductor Nanostructures: Quantum states and electronic transport
T. Ihn (2010)
Enhanced magnetoresistance in layered magnetic structures with antiferromagnetic interlayer exchange.
The influence of edge structure on the electronic properties of graphene quantum dots and nanoribbons.
Kyle A Ritter (2009)
Intrinsic and extrinsic corrugation of monolayer graphene deposited on SiO2.
V. Geringer (2009)
Role of contacts in graphene transistors: A scanning photocurrent study
T. Müller (2009)
Ballistic Transport Exceeding 28 μm in CVD Grown Graphene.
L. Banszerus (2016)
Microscopic polarization in bilayer graphene
G. M. Rutter (2011)
Raman spectroscopy as probe of nanometre-scale strain variations in graphene
C. Neumann (2015)
Tunneling criteria and breakdown for low resistive magnetic tunnel junctions
B. Oliver (2003)
Giant Rashba splitting in graphene due to hybridization with gold.
D. Marchenko (2012)
Ultra-broadband light trapping using nanotextured decoupled graphene multilayers
J. Anguita (2016)
J. Fabian (2007)
Contact-induced charge contributions to non-local spin transport measurements in Co/MgO/graphene devices
F. Volmer (2015)
Toward wafer scale fabrication of graphene based spin valve devices.
A. Avsar (2011)
Resonant Raman scattering in cubic and hexagonal boron nitride
S. Reich (2005)
Spintronics: Fundamentals and applications
I. Zutic (2004)
Limitations to charge carrier transport in high quality single- and bi-layer graphene
S. Engels (2015)
Spin relaxation mechanism in graphene: resonant scattering by magnetic impurities.
D. Kochan (2014)
Pinholes may mimic tunneling
D. Rabson (2001)
Electron spin diffusion and transport in graphene
P. Zhang (2011)
Wei Han (2014)
Random Strain Fluctuations as Dominant Disorder Source for High-Quality On-Substrate Graphene Devices
N. J. Couto (2014)
Correlating spin transport and electrode magnetization in a graphene spin valve: Simultaneous magnetic microscopy and non-local measurements
A. Berger (2015)
Origin of temperature dependence in tunneling magnetoresistance
J. Åkerman (2003)
Spin relaxation in single-layer graphene with tunable mobility.
W. Han (2012)
Missing atom as a source of carbon magnetism.
M. Ugeda (2010)
Criteria for ferromagnetic–insulator–ferromagnetic tunneling
J. Åkerman (2002)
Gain modulation by graphene plasmons in aperiodic lattice lasers
S. Chakraborty (2016)
Electric field-driven coherent spin reorientation of optically generated electron spin packets in InGaAs.
S. Kuhlen (2012)
Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions
S. Yuasa (2004)
Spin-orbit gap of graphene: First-principles calculations
Yugui Yao (2007)
Spin dynamics and relaxation in graphene dictated by electron-hole puddles
D. Van Tuan (2016)
Impurity-induced spin-orbit coupling in graphene.
A. H. Castro Neto (2009)
Cloning of Dirac fermions in graphene superlattices
L. Ponomarenko (2013)
Large magnetoresistance at room temperature in ferromagnetic thin film tunnel junctions.
g Factors and Spin-Lattice Relaxation of Conduction Electrons
Y. Yafet (1963)
Spin-orbit coupling in curved graphene, fullerenes, nanotubes, and nanotube caps
D. Huertas-Hernando (2006)
Contact and edge effects in graphene devices.
E. J. H. Lee (2008)
Nanosecond spin lifetimes in single- and few-layer graphene-hBN heterostructures at room temperature.
M. Drögeler (2014)
Temperature-dependent transport in suspended graphene.
K. Bolotin (2008)
Two-bit gates are universal for quantum computation.
Spin-Orbit Coupling Effects From Graphene To Graphite
S. Konschuh (2011)
Long-lived nanosecond spin relaxation and spin coherence of electrons in monolayer MoS2 and WS2
L. Yang (2015)
Boron nitride substrates for high-quality graphene electronics.
C. Dean (2010)
Spin-orbit-mediated spin relaxation in graphene.
D. Huertas-Hernando (2009)
Pseudospin-driven spin relaxation mechanism in graphene
D. Tuan (2014)
Magnetic moment formation in graphene detected by scattering of pure spin currents.
K. M. McCreary (2012)
Tunneling between ferromagnetic films
M. Julliere (1975)
How close can one approach the Dirac point in graphene experimentally?
A. Mayorov (2012)
Graphene: buckle or break.
Johan M. Carlsson (2007)
Tunneling Density of States-Experiment
J. Rowell (1969)
Enhancement of spin injection from ferromagnet to graphene with a Cu interfacial layer
Chi Zhang (2012)
Spin and pseudospins in layered transition metal dichalcogenides
X. Xu (2014)
Direct-bandgap properties and evidence for ultraviolet lasing of hexagonal boron nitride single crystal
K. Watanabe (2004)
Martin P. Catherwood (1824)
Bias-dependent D'yakonov-Perel' spin relaxation in bilayer graphene
M. Diez (2012)
Fine Structure Constant Defines Visual Transparency of Graphene
R. R. Nair (2008)
Controlling inelastic light scattering quantum pathways in graphene
C. Chen (2011)
Bloch Equations with Diffusion Terms
H. C. Torrey (1956)
A Review on Graphene-Based Gas/Vapor Sensors with Unique Properties and Potential Applications
Tao Wang (2016)
Effect of electron-beam irradiation on graphene field effect devices
I. Childres (2010)
Atomically thin MoS₂: a new direct-gap semiconductor.
K. F. Mak (2010)
Atomic-scale control of graphene magnetism by using hydrogen atoms
H. González-Herrero (2016)
Über magnetische Beeinflussung der Polarisation der Resonanzfluoreszenz
W. Hanle (1991)
A two-dimensional spin field-effect switch
W. Yan (2016)
Long distance spin communication in chemical vapour deposited graphene
M. Kamalakar (2015)
Tunnel magnetoresistance of 604% at 300K by suppression of Ta diffusion in CoFeB∕MgO∕CoFeB pseudo-spin-valves annealed at high temperature
S. Ikeda (2008)
Spin relaxation in single-layer and bilayer graphene.
W. Han (2011)
Electronic structure of few-layer graphene: experimental demonstration of strong dependence on stacking sequence.
K. F. Mak (2010)
Atomic structure of graphene on SiO2.
M. Ishigami (2007)
Boron nitride nanotubes and nanosheets.
D. Golberg (2010)
Nanosecond spin lifetimes in bottom-up fabricated bilayer graphene spin-valves with atomic layer deposited Al$_2$O$_3$ spin injection and detection barriers
M. Drogeler (2015)
Tunneling spin injection into single layer graphene.
W. Han (2010)
Interfacial charge-spin coupling: Injection and detection of spin magnetization in metals.
Universal magnetic properties of sp3-type defects in covalently functionalized graphene
E. Santos (2012)
Hexagonal boron nitride is an indirect bandgap semiconductor
G. Cassabois (2016)
Conditions for efficient spin injection from a ferromagnetic metal into a semiconductor
A. Fert (2001)
Highly spin-polarized room-temperature tunnel injector for semiconductor spintronics using MgO(100).
X. Jiang (2005)
Determination of work function of graphene under a metal electrode and its role in contact resistance.
Seung Min Song (2012)
A new spin on magnetic memories.
A. Kent (2015)
Resonant scattering by realistic impurities in graphene.
T. Wehling (2010)
Theory of the Effect of Spin-Orbit Coupling on Magnetic Resonance in Some Semiconductors
R. Elliott (1954)
The Band Theory of Graphite
P. Wallace (1947)
The structure of suspended graphene sheets
J. Meyer (2007)
Spin precession and inverted Hanle effect in a semiconductor near a finite-roughness ferromagnetic interface
S. Dash (2011)
Electronic Structure of Multilayer Graphene
H. Min (2008)
Electronics and optoelectronics of two-dimensional transition metal dichalcogenides.
Q. Wang (2012)
Electrical detection of spin transport in lateral ferromagnet–semiconductor devices
X. Lou (2007)
Infrared active optical vibrations of graphite
R. Nemanich (1977)
Graphene-Based Flexible and Stretchable Electronics.
Houk Jang (2016)
Drude Conductivity of Dirac Fermions in Graphene
J. Horng (2011)
Spin Orbit Coupling in Graphene Induced by Heavy Adatoms with Electrons in the Outer-Shell $p$ Orbitals
L. Brey (2015)
Observation of long spin-relaxation times in bilayer graphene at room temperature.
T-Y Yang (2011)
Breakdown of the adiabatic Born-Oppenheimer approximation in graphene.
S. Pisana (2007)
One-Dimensional Electrical Contact to a Two-Dimensional Material
L. Wang (2013)
Intrinsic and Rashba spin-orbit interactions in graphene sheets
H. Min (2006)
Imaging Spin Transport in Lateral Ferromagnet/Semiconductor Structures
S. A. Crooker (2005)
State-of-the-art graphene high-frequency electronics.
Y. Wu (2012)
Novel method for the study of spin transport in conductors
R. H. Silsbee (1980)
Spin Manipulation in Graphene by Chemically Induced Pseudospin Polarization.
D. Van Tuan (2016)
Optical properties of hexagonal boron nitride
A. Zunger (1976)
Resonant Scattering by Magnetic Impurities as a Model for Spin Relaxation in Bilayer Graphene.
D. Kochan (2015)
Theory of electrical spin injection: Tunnel contacts as a solution of the conductivity mismatch problem
E. Rashba (2000)
Resistance behavior and magnetization reversal analysis of individual Co nanowires
B. Leven (2005)
Berry's Phase and Absence of Back Scattering in Carbon Nanotubes.
T. Ando (1998)
Giant tunneling magnetoresistance up to 410% at room temperature in fully epitaxial Co∕MgO∕Co magnetic tunnel junctions with bcc Co(001) electrodes
S. Yuasa (2006)
Effect of contacts on spin lifetime measurements in graphene
Evan Sosenko (2014)
Spatial Control of Laser-Induced Doping Profiles in Graphene on Hexagonal Boron Nitride.
C. Neumann (2016)
Growth of atomically smooth MgO films on graphene by molecular beam epitaxy
W. Wang (2008)
Effect of noble-metal contacts on doping and band gap of graphene
A. Varykhalov (2010)
Photoinduced doping in heterostructures of graphene and boron nitride.
L. Ju (2014)
Hofstadter’s butterfly and the fractal quantum Hall effect in moiré superlattices
C. Dean (2013)
Electric field effect tuning of electron-phonon coupling in graphene.
Jun Yan (2007)
Graphene on transition-metal dichalcogenides: A platform for proximity spin-orbit physics and optospintronics
M. Gmitra (2015)
Theory of double-resonant Raman spectra in graphene: Intensity and line shape of defect-induced and two-phonon bands
P. Venezuela (2011)
Optical separation of mechanical strain from charge doping in graphene.
J. Lee (2012)
Line shape of the Raman 2D peak of graphene in van der Waals heterostructures
C. Neumann (2016)
Theory of spin-orbit coupling in bilayer graphene
S. Konschuh (2012)
Intact Dirac Cones at Broken Sublattice Symmetry: Photoemission Study of Graphene on Ni and Co
A. Varykhalov (2012)
Graphene: Carbon in Two Dimensions
M. Katsnelson (2006)
Electron spin relaxation in graphene: The role of the substrate
C. Ertler (2009)
Reliability of normal-state current–voltage characteristics as an indicator of tunnel-junction barrier quality
B. J. Jönsson-Åkerman (2000)
P. Liu (1998)
Seguin Hen (1824)
Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices.
Giant magnetic tunneling e ect in Fe/Al2O3/Fe junction
T. Miyazaki (1995)
Hunting for monolayer boron nitride: optical and Raman signatures.
R. Gorbachev (2011)
Colloquium: The transport properties of graphene: An introduction
N. Peres (2010)
Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2.
Y. Zhang (2014)
Spin-dependent tunnelling in magnetic tunnel junctions
E. Tsymbal (2003)
Scanning tunnelling microscopy and spectroscopy of ultra-flat graphene on hexagonal boron nitride.
J. Xue (2011)
Synthesis of large-area MoS2 atomic layers with chemical vapor deposition.
Yi-Hsien Lee (2012)
Calculation of nonlocal baseline resistance in a quasi-one-dimensional wire
M. Johnson (2007)
Raman spectroscopy of electrochemically gated graphene transistors: Geometrical capacitance, electron-phonon, electron-electron, and electron-defect scattering
Guillaume Froehlicher (2015)
Spin-half paramagnetism in graphene induced by point defects
R. R. Nair (2012)
Electric Field Effect in Atomically Thin Carbon Films
K. Novoselov (2004)
Coherent spin manipulation without magnetic fields in strained semiconductors
Y. Kato (2004)
Defect-mediated spin relaxation and dephasing in graphene.
M. Lundeberg (2013)
The role of charge traps in inducing hysteresis: Capacitance–voltage measurements on top gated bilayer graphene
Gopinadhan Kalon (2011)
Quantum spin Hall effect in graphene.
C. Kane (2005)
Ultrahigh-mobility graphene devices from chemical vapor deposition on reusable copper
L. Banszerus (2015)
Band-structure topologies of graphene: Spin-orbit coupling effects from first principles
M. Gmitra (2009)
Raman spectroscopy as a versatile tool for studying the properties of graphene.
A. Ferrari (2013)
The electronic properties of graphene
A. Neto (2009)
Commensurate-incommensurate transition in graphene on hexagonal boron nitride
C. Woods (2014)
A. Kumar (1824)
Ultra-sensitive Hall sensors based on graphene encapsulated in hexagonal boron nitride
J. Dauber (2015)
Electronic analog of the electro‐optic modulator
S. Datta (1990)
Device Concepts for Graphene-Based Terahertz Photonics
A. Tredicucci (2014)
Electronic transport in two-dimensional graphene
S. Sarma (2011)
Theory of the perpendicular magnetoresistance in magnetic multilayers.
Direct observation of a widely tunable bandgap in bilayer graphene
Y. Zhang (2009)
Revisiting the measurement of the spin relaxation time in graphene-based devices
H. Idzuchi (2015)
Electron spin relaxation in graphene from a microscopic approach: Role of electron-electron interaction
Y. Zhou (2010)
Strong suppression of weak localization in graphene.
S. Morozov (2006)
Intrinsic ripples in graphene.
A. Fasolino (2007)