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Evgeny Tsymbal Publications

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Full-Text Articles in Condensed Matter Physics

Prediction Of A Spin-Polarized Two-Dimensional Electron Gas At The Laalo3/Euo(001) Interface, Yong Wang, Manish K. Niranjan, John D. Burton, Joonhee M. An, Kirill D. Belashchenko, Evgeny Y. Tsymbal Jan 2009

Prediction Of A Spin-Polarized Two-Dimensional Electron Gas At The Laalo3/Euo(001) Interface, Yong Wang, Manish K. Niranjan, John D. Burton, Joonhee M. An, Kirill D. Belashchenko, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

First-principles calculations predict the existence of a spin-polarized two-dimensional electron gas (2DEG) at the LaO/EuO interface in a LaAlO3/EuO(001) heterostructure. This polar interface favors electron doping into the Eu-5d conduction bands resulting in a 2DEG formed at the interface.

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Universality Of The Surface Magnetoelectric Effect In Half-Metals, Chun-Gang Duan, Ce-Wen Nan, Sitaram S. Jaswal, Evgeny Y. Tsymbal Jan 2009

Universality Of The Surface Magnetoelectric Effect In Half-Metals, Chun-Gang Duan, Ce-Wen Nan, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

An electric field applied to a ferromagnetic metal produces a surface magnetoelectric effect originating from the spin-dependent screening of the electric field which results in a change in the surface magnetization of the ferromagnet.

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Prediction Of A Switchable Two-Dimensional Electron Gas At Ferroelectric Oxide Interfaces, Manish K. Niranjan, Yong Wang, Sitaram S. Jaswal, Evgeny Y. Tsymbal Jan 2009

Prediction Of A Switchable Two-Dimensional Electron Gas At Ferroelectric Oxide Interfaces, Manish K. Niranjan, Yong Wang, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

The demonstration of a quasi-two-dimensional electron gas (2DEG) in LaAlO3=SrTiO3 heterostructures has stimulated intense research activity in recent years. The 2DEG has unique properties that are promising for applications in all-oxide electronic devices. For such applications it is desirable to have the ability to control 2DEG properties by external stimulus. Here, based on first-principles calculations we predict that all-oxide heterostructures incorporating ferroelectric constituents, such as KNbO3=ATiO3 (A = Sr, Ba, Pb), allow creating a 2DEG switchable between two conduction states by ferroelectric polarization reversal. The effect occurs due to the screening charge at …

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Prediction Of Electrically Induced Magnetic Reconstruction At The Manganite/Ferroelectric Interface, John D. Burton, Evgeny Y. Tsymbal Jan 2009

Prediction Of Electrically Induced Magnetic Reconstruction At The Manganite/Ferroelectric Interface, John D. Burton, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

The control of magnetization via the application of an electric field, known as magnetoelectric coupling, is among the most fascinating and active research areas today. In addition to fundamental scientific interest, magnetoelectric effects may lead to new device concepts for data storage and processing. There are several known mechanisms for magnetoelectric coupling that include intrinsic effects in single-phase materials, strain-induced coupling in two-phase composites, and electronically driven effects at interfaces. Here we explore a different type of magnetoelectric effect at a ferromagnetic-ferroelectric interface: magnetic reconstruction induced by switching of electric polarization.

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Oxide Tunnel Junctions Supporting A Two-Dimensional Electron Gas, John D. Burton, Julian P. Velev, Evgeny Y. Tsymbal Jan 2009

Oxide Tunnel Junctions Supporting A Two-Dimensional Electron Gas, John D. Burton, Julian P. Velev, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

The discovery of a two-dimensional electron gas (2DEG) at the interface between insulating oxides has led to a well-deserved level of excitement due to possible applications as “in-plane” all-oxide nanoelectronics. Here we expand the range of possibilities to the realm of “out-of-plane” nanoelectronics by examining such all-oxide heterostructures as barriers in tunnel junctions.

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Surface Magnetoelectric Effect In Ferromagnetic Metal Films, Chun-Gang Duan, Julian P. Velev, Renat F. Sabirianov, Ziqiang Zhu, Junhao Chu, Sitaram S. Jaswal, Evgeny Y. Tsymbal Sep 2008

Surface Magnetoelectric Effect In Ferromagnetic Metal Films, Chun-Gang Duan, Julian P. Velev, Renat F. Sabirianov, Ziqiang Zhu, Junhao Chu, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

A surface magnetoelectric effect is revealed by density-functional calculations that are applied to ferromagnetic Fe(001), Ni(001), and Co(0001) films in the presence of an external electric field. The effect originates from spin-dependent screening of the electric field which leads to notable changes in the surface magnetization and the surface magnetocrystalline anisotropy. These results are of considerable interest in the area of electrically controlled magnetism and magnetoelectric phenomena.

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Interface Effects In Spin-Polarized Metal/Insulator Layered Structures, Julian P. Velev, Peter A. Dowben, Evgeny Y. Tsymbal, Stephen J. Jenkins, A. N. Caruso Sep 2008

Interface Effects In Spin-Polarized Metal/Insulator Layered Structures, Julian P. Velev, Peter A. Dowben, Evgeny Y. Tsymbal, Stephen J. Jenkins, A. N. Caruso

Evgeny Tsymbal Publications

Recent advances in thin-film deposition techniques, such as molecular beam epitaxy and pulsed laser deposition, have allowed for the manufacture of heterostructures with nearly atomically abrupt interfaces. Although the bulk properties of the individual heterostructure components may be well-known, often the heterostructures exhibit novel and sometimes unexpected properties due to interface effects. At heterostructure interfaces, lattice structure, stoichiometry, interface electronic structure (bonding, interface states, etc.), and symmetry all conspire to produce behavior different from the bulk constituents. This review discusses why knowledge of the electronic structure and composition at the interfaces is pivotal to the understanding of the properties of …

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Reversal Of Spin Polarization In Fe/Gaas (001) Driven By Resonant Surface States: First-Principles Calculations, Athanasios N. Chantis, Kirill D. Belashchenko, D. L. Smith, Evgeny Y. Tsymbal, Mark Van Schilfgaarde, R. C. Albers Nov 2007

Reversal Of Spin Polarization In Fe/Gaas (001) Driven By Resonant Surface States: First-Principles Calculations, Athanasios N. Chantis, Kirill D. Belashchenko, D. L. Smith, Evgeny Y. Tsymbal, Mark Van Schilfgaarde, R. C. Albers

Evgeny Tsymbal Publications

A minority-spin resonant state at the Fe/GaAs(001) interface is predicted to reverse the spin polarization with the voltage bias of electrons transmitted across this interface. Using a Green's function approach within the local spin-density approximation, we calculate the spin-dependent current in a Fe/GaAs/Cu tunnel junction as a function of the applied bias voltage. We find a change in sign of the spin polarization of tunneling electrons with bias voltage due to the interface minority-spin resonance. This result explains recent experimental data on spin injection in Fe/GaAs contacts and on tunneling magnetoresistance in Fe/GaAs/Fe magnetic tunnel junctions.

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Bias Voltage Dependence Of Tunneling Anisotropic Magnetoresistance In Magnetic Tunnel Junctions With Mgo And Al2O3 Tunnel Barriers, Li Gao, Xin Jiang, See-Hun Yang, John D. Burton, Evgeny Y. Tsymbal, Stuart S. P. Parkin Nov 2007

Bias Voltage Dependence Of Tunneling Anisotropic Magnetoresistance In Magnetic Tunnel Junctions With Mgo And Al2O3 Tunnel Barriers, Li Gao, Xin Jiang, See-Hun Yang, John D. Burton, Evgeny Y. Tsymbal, Stuart S. P. Parkin

Evgeny Tsymbal Publications

Tunneling anisotropic magnetoresistance (TAMR) is observed in tunnel junctions with transition metal electrodes as the moments are rotated from in-plane to out-of-plane in sufficiently large magnetic fields that the moments are nearly parallel to one another. A complex angular dependence of the tunneling resistance is found with twofold and fourfold components that vary strongly with bias voltage. Distinctly different TAMR behaviors are obtained for devices formed with highly textured crystalline MgO(001) and amorphous Al2O3 tunnel barriers. A tight-binding model shows that a fourfold angular dependence can be explained by the presence of an interface resonant state that …

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Defect-Mediated Properties Of Magnetic Tunnel Junctions, Julian P. Velev, Mikhail Ye. Zhuravlev, Kirill D. Belashchenko, Sitaram S. Jaswal, Evgeny Y. Tsymbal, T. Katayama, S. Yuasa Jun 2007

Defect-Mediated Properties Of Magnetic Tunnel Junctions, Julian P. Velev, Mikhail Ye. Zhuravlev, Kirill D. Belashchenko, Sitaram S. Jaswal, Evgeny Y. Tsymbal, T. Katayama, S. Yuasa

Evgeny Tsymbal Publications

Defects play an important role in the properties of metal oxides which are currently used as barrier layers in magnetic tunnel junctions (MTJs). We study the effect of O vacancies on the interlayer exchange coupling (IEC) and tunneling magnetoresistance (TMR) in Fe–MgO–Fe tunnel junctions. Measurements of IEC in fully epitaxial Fe–MgO–Fe(001) tunnel junctions show IEC is antiferromagnetic (AFM) for small MgO thickness but changes sign and then vanishes for large barrier thickness. First-principles calculations based on density functional theory demonstrate that the presence of neutral O vacancies (F-centers) in the MgO barrier can explain this behavior. Resonant tunneling …

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Interface Effects In Spin-Dependent Tunneling, Evgeny Y. Tsymbal, Kirill D. Belashchenko, Julian P. Velev, Sitaram S. Jaswal, Mark Van Schilfgaarde, Ivan I. Oleynik, Derek A. Stewart Feb 2007

Interface Effects In Spin-Dependent Tunneling, Evgeny Y. Tsymbal, Kirill D. Belashchenko, Julian P. Velev, Sitaram S. Jaswal, Mark Van Schilfgaarde, Ivan I. Oleynik, Derek A. Stewart

Evgeny Tsymbal Publications

In the past few years the phenomenon of spin dependent tunneling (SDT) in magnetic tunnel junctions (MTJs) has aroused enormous interest and has developed into a vigorous field of research. The large tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible application in random access memories and magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of SDT. One such question is the role of interfaces in MTJs and their effect on the spin polarization of the tunneling current and TMR. In this paper we consider different models which suggest that the …

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Atomic Motion In Ferromagnetic Break Junctions: Comment And Response, S.-F. Shi, David C. Ralph, Andrei Sokolov, Chunjuan Zhang, Evgeny Y. Tsymbal, Jody G. Redepenning, Bernard Doudin Jan 2007

Atomic Motion In Ferromagnetic Break Junctions: Comment And Response, S.-F. Shi, David C. Ralph, Andrei Sokolov, Chunjuan Zhang, Evgeny Y. Tsymbal, Jody G. Redepenning, Bernard Doudin

Evgeny Tsymbal Publications

Authors’ response

In their comment, Shi and Ralph emphasize that conductance of Ni point contacts produced by an electro-migration technique can occasionally exhibit two-level fluctuations (TLF), mimicking the discrete steps in the conductance of the point contacts as a function of the applied magnetic-field direction. They explain the nature of these steps in terms of atomic motion rather than intrinsic electronic effect. We emphasize in this reply that our results, obtained on a different magnetic material synthesized by a different method, do not show a

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Atomic And Electronic Structure Of Cofeb/Mgo Interface From First Principles, John D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal, O. G. Heinonen Oct 2006

Atomic And Electronic Structure Of Cofeb/Mgo Interface From First Principles, John D. Burton, Sitaram S. Jaswal, Evgeny Y. Tsymbal, O. G. Heinonen

Evgeny Tsymbal Publications

First-principles calculations of the atomic and electronic structure of crystalline CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) are performed to understand the effect of B on spin-dependent transport in these junctions. The authors find that it is energetically favorable for B atoms to reside at the crystalline CoFeB/MgO interface rather than remain in the bulk of the crystalline CoFeB electrode. The presence of B at the interfaces is detrimental to tunneling magnetoresistance (TMR) because it significantly suppresses the majority-channel conductance through states of symmetry. Preventing B segregation to the interfaces during annealing should result in an enhanced TMR in CoFeB/MgO/CoFeB MTJs.

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Interlayer Exchange Coupling In Fe/Mgo/Fe Magnetic Tunnel Junctions, T. Katayama, S. Yuasa, Julian P. Velev, M. Ye. Zhuravlev, Sitaram S. Jaswal, Evgeny Y. Tsymbal Sep 2006

Interlayer Exchange Coupling In Fe/Mgo/Fe Magnetic Tunnel Junctions, T. Katayama, S. Yuasa, Julian P. Velev, M. Ye. Zhuravlev, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

Interlayer exchange coupling (IEC) in fully epitaxial Fe/MgO/Fe (001) tunnel junctions with wedge-shaped MgO layers is measured at room temperature from the unidirectional shift of the Kerr hysteresis loop. It is found that the IEC is antiferromagnetic for small MgO thickness but changes sign at 0.8 nm. Ab initio calculations of IEC show that this behavior can be explained by the presence of O vacancies in the MgO barrier which makes IEC antiferromagnetic for thin barriers. With increasing MgO thickness the resonance contribution to IEC from localized defect states is reduced resulting in the ferromagnetic coupling typical for perfect MgO …

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Magnetic Moment Softening And Domain Wall Resistance In Ni Nanowires, John D. Burton, Renat F. Sabirianov, Sitaram S. Jaswal, Evgeny Y. Tsymbal, O. N. Mryasov Aug 2006

Magnetic Moment Softening And Domain Wall Resistance In Ni Nanowires, John D. Burton, Renat F. Sabirianov, Sitaram S. Jaswal, Evgeny Y. Tsymbal, O. N. Mryasov

Evgeny Tsymbal Publications

We perform ab initio calculations of the electronic structure and conductance of atomic-size Ni nanowires with domain walls only a few atomic lattice constants wide. We show that the hybridization between noncollinear spin states leads to a reduction of the magnetic moments in the domain wall resulting in the enhancement of the domain wall resistance. Experimental studies of the magnetic moment softening may be feasible with modern techniques such as scanning tunneling spectroscopy.

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Tunneling Across A Ferroelectric, Evgeny Y. Tsymbal, Hermann Kohlstedt Jul 2006

Tunneling Across A Ferroelectric, Evgeny Y. Tsymbal, Hermann Kohlstedt

Evgeny Tsymbal Publications

Spontaneously polarized materials through which electrons pass by tunneling may be used in novel electronic devices and may reveal new basic physics at the nanometer scale.

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Predicted Magnetoelectric Effect In Fe/Batio3 Multilayers: Ferroelectric Control Of Magnetism, Chun-Gang Duan, Sitaram S. Jaswal, Evgeny Y. Tsymbal Jul 2006

Predicted Magnetoelectric Effect In Fe/Batio3 Multilayers: Ferroelectric Control Of Magnetism, Chun-Gang Duan, Sitaram S. Jaswal, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

An unexplored physical mechanism which produces a magnetoelectric effect in ferroelectricferromagnetic multilayers is studied based on first-principles calculations. Its origin is a change in bonding at the ferroelectric-ferromagnet interface that alters the interface magnetization when the electric polarization reverses. Using Fe/BaTiO3 multilayers as a representative model, we show a sizable difference in magnetic moments of Fe and Ti atoms at the two interfaces dissimilar by the orientation of the local electric dipole moments. The predicted magnetoelectric effect opens a new direction to control magnetic properties of thin-film layered structures by electric fields.

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Spin-Dependent Tunneling In Magnetic Tunnel Junctions, Evgeny Y. Tsymbal, O. N. Mryasov, Patrick R. Leclair Jan 2003

Spin-Dependent Tunneling In Magnetic Tunnel Junctions, Evgeny Y. Tsymbal, O. N. Mryasov, Patrick R. Leclair

Evgeny Tsymbal Publications

The phenomenon of electron tunneling has been known since the advent of quantum mechanics, but continues to enrich our understanding of many fields of physics, as well as creating sub-fields on its own. Spin-dependent tunneling in magnetic tunnel junctions (MTJs) has recently aroused enormous interest and has developed in a vigorous field of research. The large tunneling magnetoresistance (TMR) observed in MTJs garnered much attention due to possible applications in non-volatile random access memories and next-generation magnetic field sensors. This led to a number of fundamental questions regarding the phenomenon of spindependent tunneling. In this review article we present an …

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Spin Injection Into Amorphous Semiconductors, Evgeny Y. Tsymbal, V. M. Burlakov, Ivan I. Oleinik Aug 2002

Spin Injection Into Amorphous Semiconductors, Evgeny Y. Tsymbal, V. M. Burlakov, Ivan I. Oleinik

Evgeny Tsymbal Publications

Using a realistic model for the atomic and electronic structure of amorphous silicon, we explore spin injection into amorphous semiconductors. We calculate the spin-dependent conductance of magnetoresistive devices within the Landauer-Büttiker formalism including inelastic scattering. We find that reducing the density of injected carriers and increasing the spin polarization of the electrodes are favorable for spin injection, whereas inelastic scattering is detrimental, and show that the upper limit for magnetoresistance is given by Julliere's formula.

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Atomic And Electronic Structure Of Co/Srtio3/Co Tunnel Junctions, Ivan I. Oleinik, Evgeny Y. Tsymbal, David G. Pettifor Dec 2001

Atomic And Electronic Structure Of Co/Srtio3/Co Tunnel Junctions, Ivan I. Oleinik, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

First-principles density-functional calculations of the atomic and electronic structure of Co/SrTiO3 /Co (001) magnetic tunnel junctions (MTJ’s) are performed. Different interface terminations are considered and the most stable structure with the TiO2 termination is identified based on energetics of adhesion. The calculated electronic structure of the TiO2-terminated MTJ shows an exchange coupling between the interface Co and Ti atoms mediated by oxygen. This coupling induces a magnetic moment of 0.25 µB on the interface Ti atom, which is aligned antiparallel to the magnetic moment of the Co layer. We argue that this might cause an …

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Local Impurity-Assisted Conductance In Magnetic Tunnel Junctions, Evgeny Y. Tsymbal, David G. Pettifor Nov 2001

Local Impurity-Assisted Conductance In Magnetic Tunnel Junctions, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

Using a simple tight-binding model and the Kubo formula we have calculated the lateral distribution of the tunneling conductance across a magnetic tunnel junction probed by STM. We find that the presence of an isolated impurity within the barrier layer can cause a spike in the conductance distribution, which is in agreement with recent experiments. We show that the local tunneling magnetoresistance (TMR) is very sensitive to the electronic state of the impurity and to the lateral position of the tip. The latter dramatic variation in TMR could be detected by STM.

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Perspectives Of Giant Magnetoresistance, Evgeny Y. Tsymbal, David G. Pettifor Jan 2001

Perspectives Of Giant Magnetoresistance, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

Giant magnetoresistance (GMR) is one of the most fascinating discoveries in thin-film magnetism, which combines both tremendous technological potential and deep fundamental physics. Within a decade of GMR being discovered in 1988 commercial devices based on this phenomenon, such as hard-disk read-heads, magnetic field sensors and magnetic memory chips, had become available in the market. These achievements would not have been possible without a detailed understanding of the physics of GMR, which requires a quantum-mechanical insight into the electronic spin-dependent transport in magnetic structures.

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Effect Of Disorder On Perpendicular Magnetotransport In Co/Cu Multilayers, Evgeny Y. Tsymbal Aug 2000

Effect Of Disorder On Perpendicular Magnetotransport In Co/Cu Multilayers, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

We investigate the spin-dependent conductance of the Co/Cu multilayers in the current-perpendicular-tothe- plane (CPP) geometry. Using a realistic tight-binding model for the electronic band structure of the multilayer, and introducing disorder in the on-site atomic energies we calculate the conductance and giant magnetoresistance (GMR) within the quantum-mechanical linear response theory by performing averaging over random disorder configurations. By varying the thickness and the number of individual layers and the degree of disorder in the multilayers, we analyze factors influencing the CPP GMR. In particular, we show the importance of the thickness-dependent interface resistance, which depends on the mean free path …

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Theory Of Magnetostatic Coupling In Thin-Film Rectangular Magnetic Elements, Evgeny Y. Tsymbal Aug 2000

Theory Of Magnetostatic Coupling In Thin-Film Rectangular Magnetic Elements, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

A theory of magnetostatic coupling in thin-film uniformly magnetized arrays of rectangular magnetic elements is presented. Analytic expressions for the magnetostatic energy and the dipolar fields are derived. The influence of the aspect ratio and the spacing between the elements on the magnetostatic coupling is investigated. It is found that increasing the aspect ratio reduces the critical distance between the elements, above which the magnetostatic inter-element coupling can be neglected.

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Oxygen-Induced Positive Spin Polarization From Fe In The Vacuum Barrier, Evgeny Y. Tsymbal, Ivan I. Oleinik, David G. Pettifor May 2000

Oxygen-Induced Positive Spin Polarization From Fe In The Vacuum Barrier, Evgeny Y. Tsymbal, Ivan I. Oleinik, David G. Pettifor

Evgeny Tsymbal Publications

Bonding at the ferromagnet–insulator interface is an important factor which influences spin polarization of the tunneling current in ferromagnetic tunnel junctions. In this article we investigate the spin-polarized electronic structure of the (001) surface of body-centered-cubic iron covered by an oxygen overlayer, as this could reflect the mechanism of bonding and spin polarization in iron/oxide tunnel junctions. The Fe/O atomic structure is optimized using the plane-wave code CASTEP within the spin-polarized generalized-gradient approximation. The electronic structure and local densities of states are calculated using the linear muffin-tin orbital method. The results show hybridization of the iron 3d orbitals with …

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Structural And Electronic Properties Of Cobalt/Alumina Tunnel Junctions From First Principles, Ivan I. Oleinik, Evgeny Y. Tsymbal, David G. Pettifor Mar 2000

Structural And Electronic Properties Of Cobalt/Alumina Tunnel Junctions From First Principles, Ivan I. Oleinik, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

A detailed first-principles study of the atomic and electronic structure of the Co/Al2O3/Co magnetic tunnel junction has been performed in order to elucidate the key features determining the spin-dependent tunneling. The atomic structure of the multilayer with the O- and Al-terminated interfaces between fcc Co(111) and crystalline α-Al2O3(0001) has been optimized using self-consistent spin-polarized calculations within densityfunctional theory and the generalized gradient approximation. We found that the relaxed atomic structure of the O-terminated interface is characterized by a rippling of the Co interfacial plane, the average Co-O bond length being 2.04 Å …

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Quantum-Well Resistivity For Perpendicular Transport In Magnetic Layered Systems, Evgeny Y. Tsymbal, David G. Pettifor Jan 2000

Quantum-Well Resistivity For Perpendicular Transport In Magnetic Layered Systems, Evgeny Y. Tsymbal, David G. Pettifor

Evgeny Tsymbal Publications

We show that quantum-well states enhance the current-perpendicular-to-planes resistivity of a metal film compared to the resistivity in the bulk at film thicknesses comparable with the mean free path due to the reduced number of conducting channels within the potential-well structure. This makes the mean free path an important parameter, which must be taken into account for the accurate treatment of results on currentperpendicular- to-plane giant magnetoresistance, rather than ignored by applying the two-current series-resistor model.

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Electronic Scattering From Co/Cu Interfaces: In-Situ Measurement And Comparison With Theory, W. E. Bailey, Shan X. Wang, Evgeny Y. Tsymbal Jan 2000

Electronic Scattering From Co/Cu Interfaces: In-Situ Measurement And Comparison With Theory, W. E. Bailey, Shan X. Wang, Evgeny Y. Tsymbal

Evgeny Tsymbal Publications

The full thickness-dependent electrical conductivity of polycrystalline NiO/Co/Cu/Co spin-valve structures was measured in situ during ion-beam deposition and compared with calculations based on realistic band structure. We have found striking features in the experimental conductivity which are unexpected from widely used semiclassical free-electron models. Addition of ∼ 1 ML Co to a NiO/Co/Cu surface causes the net film conductance to decrease; the reverse case of Cu on NiO/Co shows a strong positive curvature of the thicknessdependent conductance, indicating a reduction of the conductivity in Cu near the interface with Co. Quantitative agreement is found between the experimental thickness-dependent film conductance …

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