Bias-controlled spin polarization in quantum wires pdf

An electron spin is an example of a twolevel quantum system that may be used as a qubit in a quantum computer. Full text of measurement of the cmb polarization at 95. Conductance quantization suppression in the quantum hall. Both electrodes are spin coated with sulfonic pi as the alignment layers and are photoaligned. This phenomenon is observed in quasi onedimensional conductors at zero magnetic field b, and the formation of edge states at finite magnetic fields results in wider conductance plateaus within the quantum hall regime. Majority and minoritygate logic schemes based on magneto. Paul crowell has been on the faculty of the university of minnesota since 1997 and is currently a professor of physics. The intuitive argument in favour of spontaneous spin polarization is. Spinpolarized transport calculations through the leadmultidecker moleculelead junctions predicted large biascontrolled magnetoresistive response, with the highest gmr ratio up to 2. Atomic, molecular and optical physics, volume 43, number 15.

Devices and application that employ the multiple squid magnetometers are also provided. Electrons in one dimension philosophical transactions of. The spin polarization of currents, between full spin polarization and partial spin polarization or spin degeneracy, is thus simply controlled by sourcedrain bias and splitgate voltage. When a sourcedrain bias lifts the momentum degeneracy, the dc measurements show that it is possible to achieve a unidirectional ferromagnetic order and this ordered spin array is destroyed once transport in both directions commences. Assisted extraction of the energy level spacings and lever arms in direct current bias measurements of onedimensional quantum wires, using an image recognition routine. Multiple squid magnetometers that include at least two squid loops, each of which is composed of at least two josephson junctions connected in parallel with superconducting wires, are provided. Spin filtering in fourterminal wire networks with spin. Optical nano and microsystems for bioanalytics pdf free. However, a sign change of the spin polarization with bias was predicted in. Published 7 july 2010 2010 iop publishing ltd journal of physics b. Pdf spontaneous spin polarization in quantum wires.

An introduction to the formulation of steadystate transport through molecular junctions. Biascontrolled spin polarization in quantum wires article pdf available in applied physics letters 933. Spinpolarized transport calculations through the leadmultidecker moleculelead junctions predicted large biascontrolled. Bursting of the bonds remains, before they who seek to control and to eliminate half of the. Nearly perfect spin filter based on a wire of half. The study of molecular junctions has attracted much interest in recent years. Graduate of the university of athens, greece, professor pavlos lagoudakis received his phd degree in physics from the university of southampton, uk in 2003 and conducted his postdoctoral research on optoelectronic properties of organic semiconductors at the ludwig maximilians university of. Conductance quantization is the hallmark of noninteracting confined systems. Some approaches tap quantum uncertainty, such as amplified spontaneous emission, while others use chaotic dynamics to exploit classical uncertainty, such as laser systems destabilized by optical feedback. The amplitude and the sign of the spin filter efficiency can be manipulated by choosing the contact condition e.

Biastunable electron transport in a magnetic doublebarrier. Conductance quantization is the quintessential feature of electronic transport in noninteracting mesoscopic systems. Pdf allelectrical control of spin transport in nanostructures has been the central interest and challenge of. Spin is believed to play an important role in these e ect. An oscillation behavior of the molecular magnetic moments was observed. The squid loops are fabricated such that they share a common josephson junction. The rkky coupling is proportional to the spin susceptibility n q of the conduction electrons. Pdf biascontrolled spin polarization in quantum wires. The tilted white line highlighted by the black dashed line corresponds to the points where the spin signal changes sign. Two quantum point contacts are used to respectively inject and detect spins by purely electrical means in an allsemiconductor spin transistor. We have studied theoretically the magnetotransport in a ferromagnetic resonant tunneling diode frtd, where alternating magnetic ga 1x mn x as and nonmagnetic gaas and alas layers give rise to strongly spin polarization dependent electronic transport. We have studied theoretically the magnetotransport in a ferromagnetic resonant tunneling diode frtd, where alternating magnetic ga 1x mn x as and nonmagnetic gaas and alas layers give rise to strongly spinpolarization dependent electronic transport. Assisted extraction of the energy level spacings and lever. We analyze here the possibility to change the spin polarization of an electron beam which is reflected from a barrier in the 2d plane.

In this article, we present a summary of the current status of the study of the transport of electrons confined to one dimension in very low disorder gaasalgaas heterostructures. A memtj device includes an exchange biascontrolled switching element and a pinned ferromagnetic layer on an antiferromagnetic layer. Roomtemperature triggered single photon emission from a iii. The first term is the lowering of the energy due to the indirect rkky exchange interaction via the spin polarization of the conduction electrons in the normal state. Semiconductor quantum dots have been investigated intensively for potential applications in solidstate quantum information processing and spintronics, such as singlephoton sources 1,2,3,4,5,6,7,8, excitonic qubits 9, spin qubits 10,11,12,14,15, and spinphoton entanglement interfaces 16,17,18. A strong bias dependence of spin polarization qualitatively di ers from the simple description of spin injection based on the equivalent resistor scheme and a linear i vcharacteristics. Ultrafast manipulation of magnetic order with electrical pulses by yang yang doctor of philosophy in materials science and engineering university of california, berkeley during the last 30 years spintronics has been a very rapidly expanding field leading to lots of. Controlling singleparticle wave functions is a key step to understand quantum physics and to. Electricfield control of magnetization in biased semiconductor quantum wires and. We demonstrate that a sourcedrain bias creates a fully spin polarized current as the 0.

We report a longitudinal wave function control in single quantum dots with a magnetic field. Ti units sicong zhu,1,2 jianming fang,1 kailun yao,1 and yanqing wu1,2, 1wuhan national high magnetic field center and school of physics. Both electrodes are spincoated with sulfonic pi as the alignment layers and are photoaligned. The spin polarization of currents, between full spin polarization and partial spin polarization or spin degeneracy, is thus simply controlled by sourcedrain bias and splitgate voltage, something of considerable value for spintronics. When a sourcedrain bias lifts the momentum degeneracy, the dc measurements show that it is possible to achieve a unidirectional ferromagnetic order and this ordered spin array is destroyed once transport in both directions. After a quantum computation, the value of the qubit must be measured. Transducers international official journal of the international frequency sensor association ifsa devoted to research and development of sensors and transducers volume 193, issue 10, october 2015 editorinchief prof. Spin polarization and exchange interaction in a diluted. We investigated giant magnetoresistance gmr across cyclopentadienyliron multidecker molecules femc5h5n using the density functional theory and nonequilibrium greens function techniques. A strong biasdependence of spinpolarization qualitatively di ers from the simple description of spin injection based on the equivalent resistor scheme and a linear i vcharacteristics. We use carbon nanotubes to fabricate quantum dots with ferromagnetic electrodes 1,2,3,21,22,23. Oct 18, 2007 after a quantum computation, the value of the qubit must be measured.

Owing to the transverse anisotropy of our ferromagnetic electrodes 24, one can obtain quantum dots with noncollinear leads by defining with ebeam lithography magnetic electrodes forming an angle, as shown in fig. Ritchie, biascontrolled spin polarization in quantum wires. Pdf electricfield control of magnetization in biased semiconductor. Spin polarization in modulationdoped gaas quantum wires. Biascontrolled spin polarization in quantum wires aip publishing. In conclusion, the spin polarization energy of a confined donor electron has been studied for different concentrations of mn ions for the finite dot of cd 1. Longitudinal wave function control in single quantum dots. An analysis of the relative contributions due to linear, quadratic, and cubic dresselhaus spinorbit terms on the energy levels, spin splitting, and spin polarization has been carried out. While the idea of using single molecules as components in nanoelectronic devices is an old one, advances in fabrication techniques led to several experimental realizations of singlemolecule junctions, with a large impact on theoretical work aiming to model and to simulate the molecular junction scenarios.

In twodimensional semiconductor structures rashba spin orbit coupling can orient the electrons spin in two opposite directions perpendicular to the direction of motion. An apparatus and methods for optical switching using nanoscale optics are disclosed herein. These states are of great interest for quantum information applications as well as fundamental physics because they decay to a ground state which is composed of a single trapped spin, and information about that spin can be obtained through the polarization of the emitted photon, as. Spin depolarization in quantum wires polarized spontaneously in.

It is shown that nearly full output spin polarization can be obtained for the 4terminal square network of specific horizontal sizes when the vertical size is large. Majority and minority logic can be implemented by voltage controlled switching of magnetoelectric layers of magneto electric magnetic tunnel junction memtj devices. Dec 22, 2014 two quantum point contacts are used to respectively inject and detect spins by purely electrical means in an allsemiconductor spin transistor. Polyimide pi is an organic insulating material with a low dielectric constant. Moreover, we reveal a remarkable temperature insensitivity of the single photon statistics, and a g20 value at 300 k of just 0. We investigate theoretically the donor bound spin polaronic e. Nearly perfect spin filter based on a wire of halfmetallic 5 8. A nanooptics apparatus for use as an optical switch includes a metallic film having a top surface, a bottom surface and a plurality of cylindrical channels containing a dielectric material, the metallic film acting as an outer electrode.

While a net spin polarization appears in all cases, the spin filtering effect is significantly enhanced when the co adatom is at the edge, where the adsorption energy is maximized and a partial suppression of edgeassociated transport channels occurs. In addition, we present intriguing new evidence that a fully spinpolarised state can be induced in a quantum wire at zero magnetic field simply by applying a large dcbias. Ultrafast manipulation of magnetic order with electrical pulses. M ii 2000 emc ataglance wednesday morning, june 21, 2000 session d. The optical axis of the lc is initially parallel to the connecting wires. An introduction to the formulation of steadystate transport. The positive to negative conversion of the gmr values was also observed with. As mentioned in the main text, a number of theoretical papers have been published, suggesting that a spin polarization does occur in qpcs and quantum wires, despite the theorem of lieb and mattis that states that the ground state of a onedimensional system is nonmagnetic. The studies of the spontaneous spin polarization in quantum wires that have been carried.

Oct 05, 2017 this allows one to switch from a parallel to antiparallel magnetization configuration of the electrodes by application of a magnetic field, thereby affecting the scattering or tunneling properties of the charge carriers. Distinct engineering architectures of spinorbit coupling are exploited for the quantum point contacts and the central semiconductor channel to achieve. Imaging the zigzag wigner crystal in confinementtunable quantum. Jul 23, 2008 we demonstrate that a sourcedrain bias creates a fully spinpolarized current as the 0. Earth without polarity free ebook download as pdf file. Most electron paramagnetic resonance epr, also known as esr or emr experimen. Us7649665b2 apparatus and methods for optical switching.

New interaction effects in quantum point contacts at high. The magnetization of mn subsystems and the strength of spin exchange energy of confined electrons have been discussed. When a sourcedrain bias lifts the momentum degeneracy, the dc measurements show that it is possible to achieve a unidirectional ferromagnetic order and this ordered spin array is destroyed. In a wider perspective, our study demonstrates radical disruptions of the. Allelectric and allsemiconductor spin field effect transis tors. However, the spin polarization changes sign when the fermi level, whose position can be controlled by an external gate voltage, crosses the dirac points. In twodimensional semiconductor structures rashba spinorbit coupling can orient the electrons spin in two opposite directions perpendicular to the direction of motion. Biascontrolled spin polarization in quantum wires core.

Although demonstrated here in graphene, this is a universal phenomenon 4, 9 11, 27 occurring in ballistic, narrow conducting systems exhibiting hardwall potential confinement such as semiconducting and metallic 2d crystals or cleavededged overgrown quantum wires 31. Spin filtering in fourterminal wire networks with spinorbit. The authors show that the quantization in graphene nanoconstrictions. Harnessing spin precession with dissipation europe pmc. We study the spin polarization and conductance in infinitely long quasi onedimensional quantum wires under various conditions in an attempt to reproduce and to explain some of the anomalous conductance features as seen in various experiments.

For a pure inas quantum dot with a shape of pyramid or truncated pyramid, the hole wave function always occupies the base because of the less confinement at base, which induces a. Physica scripta, volume 2002, t101, 2002 iopscience. The authors show that the quantization in graphene nanoconstrictions with low edge disorder is suppressed in the. Nearly perfect spin filter based on a wire of halfmetallic 5c 5h5. We demonstrate triggered single photon emission at room temperature from a site controlled iiinitride quantum dot embedded in a nanowire. The spin fieldeffect transistor envisioned by datta. New ptab petition filed petition status changed petition closed petitioner added patent owner added real partyininterest added.

Electrons injected from the confinementtunable quantum wire undergo cyclotron motion in the. We compare the behavior of the zerobias anomaly against predictions from kondo and spin polarization models. Us20070081242a1 apparatus and methods for optical switching. Mcknight land grant professor, university of minnesota 19992001, sloan foundation fellow, 19992001, mcknight presidential fellow, university of minnesota, 20042007, fellow of the american physical society, 2008. Set should be able to selectively open the analytical access to the components system and bonding wires al, cu, au materials without damaging them. Laser set for electronic component package decapsulation oriented preferably at plastic and composite packaging materials. The conditions for a spontaneous spin polarization in a quantum wire positioned in a zero magnetic. In this paper, the biasdependent electron transport is investigated in detail in a magnetic doublebarrier nanostructure in the presence of two bias. College london, london wc1e 7je, united kingdom arxiv. We demonstrate that a sourcedrain bias creates a fully spinpolarized current as the 0.

Undoped gaasalgaas heterostructures have been used to fabricate quantum wires in which the average impurity separation is greater than the device size. The conditions for a spontaneous spin polarization in a quantum wire positioned in a zero magnetic field are. Graduate of the university of athens, greece, professor pavlos lagoudakis received his phd degree in physics from the university of southampton, uk in 2003 and conducted his postdoctoral research on optoelectronic properties of organic semiconductors at the ludwig maximilians university of munich, germany. Indeed, manyif not the great majorityof the optical sensors detect only the intensity of light, while other science and technology applications have required the detection of other parameters, such as polarization or phase whose manipulation, or capture and storage are necessary in certain applications, of which holography is the best. Pdf allelectrical injection and detection of a spinpolarized.

Numerous specialized hardware devices for highspeed true random number generation have been proposed in recent years 2. Biascontrolled spin polarization in quantum wires nasaads. Ultrafast manipulation of magnetic order with electrical pulses by yang yang doctor of philosophy in materials science and engineering university of california, berkeley during the last 30 years spintronics has been a very rapidly expanding field leading to lots of new interesting physics and applications. Issn 17265479 international frequency sensor association. Mar, 2010 as mentioned in the main text, a number of theoretical papers have been published, suggesting that a spin polarization does occur in qpcs and quantum wires, despite the theorem of lieb and mattis that states that the ground state of a onedimensional system is nonmagnetic. Ultrafast manipulation of magnetic order with electrical. Spin polarization and conductance in quantum wires under. Full text of measurement of the cmb polarization at 95 ghz. Thus, in quantum computing, the qubits must retain their quantum information long enough to allow for their measurement after a calculation has been performed. Allelectric and allsemiconductor spin field effect transis tors core. Allelectric allsemiconductor spin fieldeffect transistors. Our work demonstrates that measurements of spin excitations reveal key insights on states of spin, indicating that full spin polarization is lost in the partially populated n1 landau level. Full text of measurement of the cmb polarization at 95 ghz from quiet see other formats.

Electronic spin transport through cpfecpvn multidecker wire sandwiched between magnetic nickel ni electrodes is simulated in the linear response regime based on dft. New interaction effects in quantum point contacts at high magnetic fields. The spontaneous spin polarization of a quantum point contact qpc formed by the lateral confinement of a highmobility twodimensional electron gas in a gaasalgaas split gate heterostructure is. These states are of great interest for quantum information applications as well as fundamental physics because they decay to a ground state which is composed of a single trapped spin, and information about that spin can be obtained through the polarization of the emitted photon, as shown schematically in fig. We have studied a frdt structure having a nonmagnetic quantum well between magnetic. Since spin filtering is a combined effect of spin precession and quantum interference, it is very sensitive to the structure and size of the network. Ballistic spin resonance in multisubband quantum wires.