Spin injection into a ballistic semiconductor microstructure

Kravchenko, V. Ya.; Rashba, Emmanuel I.

doi:10.1103/physrevb.67.121310

Cited by 28 publications

(22 citation statements)

References 51 publications

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“…For r c which would exceed the resistance of the N and F bulk regions, the spin injection efficiency can attain P j ϳ(r c↑ Ϫr c↓ )/r c (Kravchenko and Rashba, 2003), showing, similarly to the diffusive regime, the importance of the resistive contacts to efficient spin injection. Connection with the results in the diffusive regime can be obtained (Kravchenko and Rashba, 2003) by identifying r c ϭ1/4⌺ , where the contact conductivity ⌺ was introduced in Eq. (24).…”

Section: F/n/f Junctionmentioning

confidence: 99%

“…(119) the polarization of the transmitted electrons can be estimated to exceed 90%, even with a ferromagnet only ϳ3 nm thick (van Dijken et al, 2003b). A theoretical analysis of spin injection and spin filtering in magnetic tunneling transistors was given by Rashba (2003a) who extended the approach for ballistic spin injection (Kravchenko and Rashba, 2003;Sec. II.C.2) to include the effects of hotelectron transport and inelastic scattering.…”

Section: Hot-electron Spin Transistorsmentioning

confidence: 99%

“…The studies of intermediate cases provide an interpolation scheme between the R Maxwell and R Sharvin for various ratios of a/l (Wexler, 1966;Jansen et al, 1980;de Jong, 1994;Nikolić and Allen, 1999). Following Kravchenko and Rashba (2003) the effective contact resistance r c ϭr c↑ ϩr c↓ (recall that it is defined per unit area) is obtained as…”

Section: F/n/f Junctionmentioning

confidence: 99%

“…Considering the spin injection from F into a ballistic N region in the presence of diffusive interfacial scattering, where the phase coherence is lost and the Boltzmann equation can be applied, it is instructive to reconsider the effect of contact resistance (Kravchenko and Rashba, 2003). We introduce the Sharvin resistance R Sharvin (Sharvin, 1965), arising in ballistic transport between two infinite regions connected by a contact (an orifice or a narrow and short constriction) of radius much smaller than the mean free path, aӶl.…”

Section: F/n/f Junctionmentioning

confidence: 99%

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Spintronics: Fundamentals and applications

2004

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Spintronics, or spin electronics, involves the study of active control and manipulation of spin degrees of freedom in solid-state systems. This article reviews the current status of this subject, including both recent advances and well-established results. The primary focus is on the basic physical principles underlying the generation of carrier spin polarization, spin dynamics, and spin-polarized transport in semiconductors and metals. Spin transport differs from charge transport in that spin is a nonconserved quantity in solids due to spin-orbit and hyperfine coupling. The authors discuss in detail spin decoherence mechanisms in metals and semiconductors. Various theories of spin injection and spin-polarized transport are applied to hybrid structures relevant to spin-based devices and fundamental studies of materials properties. Experimental work is reviewed with the emphasis on projected applications, in which external electric and magnetic fields and illumination by light will be used to control spin and charge dynamics to create new functionalities not feasible or ineffective with conventional electronics. CONTENTS

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Section: F/n/f Junctionmentioning

confidence: 99%

Section: Hot-electron Spin Transistorsmentioning

confidence: 99%

Section: F/n/f Junctionmentioning

confidence: 99%

Section: F/n/f Junctionmentioning

confidence: 99%

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Spintronics: Fundamentals and applications

2004

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“…However, both the metal and semiconductor become "soft" elements if the resistance of a barrier inserted between them is larger than their effective resistances. Under these conditions, spin injection is controlled by spin selectivity of the barrier, i.e., by the difference in its resistances for up-and downspin electrons.More detailed diffusive theories of spin injection confirmed this concept [42,43], and it was generalized for ballistic transport across spin valves [44,45,46] and for optimization of Schottky barriers [47]. It also explained dramatic inefficiency of low-resistance contacts, and early observations of spin injection from STM tips [48], resonant double barriers [49], and Schottky barriers [50].…”

mentioning

confidence: 73%

Restrictions on modeling spin injection by resistor networks

Rashba¹

2008

Semicond. Sci. Technol.

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Because of the technical difficulties of solving spin transport equations in inhomogeneous systems, different resistor networks are widely applied for modeling spin transport. By comparing an analytical solution for spin injection across a ferromagnet -paramagnet junction with a resistor model approach, its essential limitations stemming from inhomogeneous spin populations are clarified. PACS numbers:Conventional electronics is based on a single parameter of electron, its charge. Therefore, electronics deals only with electron trajectories. It does not involve electron spin, its internal degree of freedom. The new paradigm of spin-based electronics, or spintronics, is based on active involvement of electron spin in transport and optical phenomena, and on employing electron spin for both information processing and information storage. During the last decade, semiconductor spintronics developed into a wide and diversified field. Early review papers [1, 2] were followed by more recent surveys covering specific scientific problems and technological perspectives of this rapidly developing field [3,4,5,6,7,8,9,10,11,12,13,14,15,16,17]. There exists close connection between the recent work on electric spin manipulation in low-dimensional systems and the previous work on anomalous Hall effect [18], electric dipole spin resonance [19], optical orientation [20] and photogalvanic effect [21,22] in three-dimensional systems. Strong impetus for semiconductor spintronics was given by the discovery of giant magnetoresistance in metallic systems [23,24] and by its impressing practical applications.Spin injection from ferromagnetic sources into paramagnetic media is believed to be an important part of the new phenomena and applications in the field of the spin-polarized electron transport. The concept of a field effect spin transistor [25] served as one of the stimuli. Successful experiments on spin injection into superconductors [26] and normal metals [27] were very promising, and theoretical work supported reliability of the idea [28,29,30,31,32,33]. Successful detection of the floating potential (spin-e.m.f., electromotive force [34]) at a ferromagnetic probe became an independent confirmation of efficient spin injection. Meantime, the methods that resulted in a remarkable success in spin injection from ferromagnetic metals into paramagnetic metals turned inefficient as applied to the spin injection from ferromagnetic metals into semiconductors. Spin injection at the level of only about 1% was reported [35,36], and persuasiveness of the results was disputed [37,38]. Absence of any measurable spin-e.m.f. also indicated that the concentration of the electrically injected nonequilibrium spins was vanishingly small [39].Inefficiency of a "perfect" contact between a ferromagnetic metal and a semiconductor as a spin emitter, that seemed puzzling, found its natural explanation in the framework of the conductivity mismatch concept [40]. The next step was proposing resistive spin selective contacts, like tunnel or Schottky barriers, a...

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Perspective on field‐effect spin‐transistors

Sugahara

2006

Phys. Status Solidi (c)

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A new class of spin transistors referred to as spin metal-oxide-semiconductor field-effect transistor (spin MOSFET) is a candidate for the fundamental building block of novel integrated circuts employing spin degrees of freedom. The most attractive feature of the spin MOSFET is spin-related transport phenomena in its output characteristics, i.e., magnetization-configuration-dependent output currents. Furthermore, the spin MOSFET can exhibit excellent performance as a transistor and would have excellent compatibility with present silicon technology. These features make the spin MOSFET attractive for new nonvolatile memory and reconfigurable logic architectures that are inaccessible to ordinary transistor circuits. Transistor performance of the spin MOSFET, such as propagation delay time, switching energy, and stand-by power, is not superior to ordinary MOSFETs on device level. However, the circuit performance would be dramatically improved by introducing spin degrees of freedom into integrated circuits.1 Introduction Progress in integrated electronics is powered by the miniaturization of device (transistor) dimension and the high degree of device integration, since the size shrinkage and large-scale integration of transistors provide improvements in performance of integrated circuits including their reliability and production cost. Recently emerging system-on-chip (SOC) architectures rely on these features of integrated circuits. Metal-oxide-semiconductor field-effect transistors (MOSFETs) and complementary MOS (CMOS) devices (hereafter both are referred to as MOS devices) based on sophisticated Si technology are a fundamental building block for the main stream of integrated circuits, and they play an essential role as a 'technology driver' in integrated electronics. This is, of course, due to the excellent scalability and integration ability of MOS devices. Rapid and continuing progress in the scaled-down technology of MOS devices, that is known as Moore's law, has excluded necessities to introduce new functionality added to MOS devices, such as quantum effects and spin-related phenomena, although these functionalities could be useful to improve the performance of integrated circuits. However, the situation has been changed. Recently, the scaling of the channel length of MOS devices has already reached the physical limit of several nanometers. Therefore, scaling-independent technologies to improve device performance are indispensable. The paradigm shift from the simple device scaling to the introduction of new functionality added to MOS devices is expected as a significantly important path for future integrated electronics technology.The aim of recently emerging spin-electronics (spintronics) research is to manipulate spin degrees of freedom in solid state devices, and provide new concepts for future electronics and photonics employing spin degrees of freedom. One of the most attractive research directions is to control charge transport and spin degrees of freedom in active electronic devices, i.e., spin transist...

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Spin injection into a ballistic semiconductor microstructure

Cited by 28 publications

References 51 publications

Spintronics: Fundamentals and applications

Spintronics: Fundamentals and applications

Restrictions on modeling spin injection by resistor networks

Perspective on field‐effect spin‐transistors

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