An apparatus and methods for optical switching using nanoscale optics are disclosed herein. We demonstrate that a sourcedrain bias creates a fully spinpolarized current as the 0. 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. Ultrafast manipulation of magnetic order with electrical pulses. M ii 2000 emc ataglance wednesday morning, june 21, 2000 session d. Assisted extraction of the energy level spacings and lever arms in direct current bias measurements of onedimensional quantum wires, using an image recognition routine. Moreover, we reveal a remarkable temperature insensitivity of the single photon statistics, and a g20 value at 300 k of just 0.
Spinpolarized transport calculations through the leadmultidecker moleculelead junctions predicted large biascontrolled magnetoresistive response, with the highest gmr ratio up to 2. 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. Nearly perfect spin filter based on a wire of half. 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. 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. The tilted white line highlighted by the black dashed line corresponds to the points where the spin signal changes sign. 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. The authors show that the quantization in graphene nanoconstrictions with low edge disorder is suppressed in the. The positive to negative conversion of the gmr values was also observed with. Nearly perfect spin filter based on a wire of halfmetallic 5 8. Numerous specialized hardware devices for highspeed true random number generation have been proposed in recent years 2. 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.
Devices and application that employ the multiple squid magnetometers are also provided. Allelectric and allsemiconductor spin field effect transis tors core. 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. 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. 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. An oscillation behavior of the molecular magnetic moments was observed. The optical axis of the lc is initially parallel to the connecting wires. 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. We use carbon nanotubes to fabricate quantum dots with ferromagnetic electrodes 1,2,3,21,22,23. Physica scripta, volume 2002, t101, 2002 iopscience. Spin depolarization in quantum wires polarized spontaneously in.
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. Nearly perfect spin filter based on a wire of halfmetallic 5c 5h5. Biascontrolled spin polarization in quantum wires aip publishing. 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. New ptab petition filed petition status changed petition closed petitioner added patent owner added real partyininterest added. 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. The studies of the spontaneous spin polarization in quantum wires that have been carried.
A memtj device includes an exchange biascontrolled switching element and a pinned ferromagnetic layer on an antiferromagnetic layer. 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. Most electron paramagnetic resonance epr, also known as esr or emr experimen. Allelectric allsemiconductor spin fieldeffect transistors. Biastunable electron transport in a magnetic double. Biascontrolled spin polarization in quantum wires nasaads. Earth without polarity free ebook download as pdf file. The authors show that the quantization in graphene nanoconstrictions. In this paper, the biasdependent electron transport is investigated in detail in a magnetic doublebarrier nanostructure in the presence of two bias. 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. Both electrodes are spincoated with sulfonic pi as the alignment layers and are photoaligned. College london, london wc1e 7je, united kingdom arxiv.
Conductance quantization is the quintessential feature of electronic transport in noninteracting mesoscopic systems. 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. Majority and minoritygate logic schemes based on magneto. Full text of measurement of the cmb polarization at 95 ghz. Electronic spin transport through cpfecpvn multidecker wire sandwiched between magnetic nickel ni electrodes is simulated in the linear response regime based on dft.
Ballistic spin resonance in multisubband quantum wires. Harnessing spin precession with dissipation europe pmc. An introduction to the formulation of steadystate transport. Biascontrolled spin polarization in quantum wires core. Longitudinal wave function control in single quantum dots. We investigate theoretically the donor bound spin polaronic e. An introduction to the formulation of steadystate transport through molecular junctions. 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. 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.
Pdf allelectrical injection and detection of a spinpolarized. In a wider perspective, our study demonstrates radical disruptions of the. Oct 18, 2007 after a quantum computation, the value of the qubit must be measured. Set should be able to selectively open the analytical access to the components system and bonding wires al, cu, au materials without damaging them. 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. 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. An electron spin is an example of a twolevel quantum system that may be used as a qubit in a quantum computer. Imaging the zigzag wigner crystal in confinementtunable quantum. 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. Spinpolarized transport calculations through the leadmultidecker moleculelead junctions predicted large biascontrolled. 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. Undoped gaasalgaas heterostructures have been used to fabricate quantum wires in which the average impurity separation is greater than the device size. Spin polarization and conductance in quantum wires under. 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.
Assisted extraction of the energy level spacings and lever. Controlling singleparticle wave functions is a key step to understand quantum physics and to. In twodimensional semiconductor structures rashba spinorbit coupling can orient the electrons spin in two opposite directions perpendicular to the direction of motion. 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. 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. Us7649665b2 apparatus and methods for optical switching. We demonstrate triggered single photon emission at room temperature from a site controlled iiinitride quantum dot embedded in a nanowire. 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.
The amplitude and the sign of the spin filter efficiency can be manipulated by choosing the contact condition e. Pdf biascontrolled spin polarization in quantum wires. We compare the behavior of the zerobias anomaly against predictions from kondo and spin polarization models. In twodimensional semiconductor structures rashba spin orbit coupling can orient the electrons spin in two opposite directions perpendicular to the direction of motion. The rkky coupling is proportional to the spin susceptibility n q of the conduction electrons. Spin polarization in modulationdoped gaas quantum wires. Electrons in one dimension philosophical transactions of.
Published 7 july 2010 2010 iop publishing ltd journal of physics b. Jul 23, 2008 we demonstrate that a sourcedrain bias creates a fully spinpolarized current as the 0. Spin is believed to play an important role in these e ect. We investigated giant magnetoresistance gmr across cyclopentadienyliron multidecker molecules femc5h5n using the density functional theory and nonequilibrium greens function techniques. 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. Pdf allelectrical control of spin transport in nanostructures has been the central interest and challenge of. Full text of measurement of the cmb polarization at 95. 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. Allelectric and allsemiconductor spin field effect transis tors. Roomtemperature triggered single photon emission from a iii.
We demonstrate that a sourcedrain bias creates a fully spin polarized current as the 0. Conductance quantization is the hallmark of noninteracting confined systems. However, the spin polarization changes sign when the fermi level, whose position can be controlled by an external gate voltage, crosses the dirac points. Electricfield control of magnetization in biased semiconductor quantum wires and. Spin filtering in fourterminal wire networks with spin. Both electrodes are spin coated with sulfonic pi as the alignment layers and are photoaligned. Two quantum point contacts are used to respectively inject and detect spins by purely electrical means in an allsemiconductor spin transistor.
We have studied a frdt structure having a nonmagnetic quantum well between magnetic. Thus, in quantum computing, the qubits must retain their quantum information long enough to allow for their measurement after a calculation has been performed. Conductance quantization suppression in the quantum hall. We report a longitudinal wave function control in single quantum dots with a magnetic field. 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. 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.
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. Optical nano and microsystems for bioanalytics pdf free. 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. 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. Electrons injected from the confinementtunable quantum wire undergo cyclotron motion in the. Bursting of the bonds remains, before they who seek to control and to eliminate half of the. Atomic, molecular and optical physics, volume 43, number 15. Pdf spontaneous spin polarization in quantum wires. Biastunable electron transport in a magnetic doublebarrier.
Laser set for electronic component package decapsulation oriented preferably at plastic and composite packaging materials. Paul crowell has been on the faculty of the university of minnesota since 1997 and is currently a professor of physics. Pdf electricfield control of magnetization in biased semiconductor. However, a sign change of the spin polarization with bias was predicted in. 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. 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. New interaction effects in quantum point contacts at high magnetic fields. 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. Biascontrolled spin polarization in quantum wires article pdf available in applied physics letters 933. The magnetization of mn subsystems and the strength of spin exchange energy of confined electrons have been discussed. Spin filtering in fourterminal wire networks with spinorbit. Us20070081242a1 apparatus and methods for optical switching. 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.
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. The intuitive argument in favour of spontaneous spin polarization 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. 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. 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. 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. Full text of measurement of the cmb polarization at 95 ghz from quiet see other formats. Ritchie, biascontrolled spin polarization in quantum wires. 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. Majority and minority logic can be implemented by voltage controlled switching of magnetoelectric layers of magneto electric magnetic tunnel junction memtj devices. Distinct engineering architectures of spinorbit coupling are exploited for the quantum point contacts and the central semiconductor channel to achieve.
The spin fieldeffect transistor envisioned by datta. Spin polarization and exchange interaction in a diluted. The study of molecular junctions has attracted much interest in recent years. We analyze here the possibility to change the spin polarization of an electron beam which is reflected from a barrier in the 2d plane. New interaction effects in quantum point contacts at high. The squid loops are fabricated such that they share a common josephson junction. After a quantum computation, the value of the qubit must be measured. Ultrafast manipulation of magnetic order with electrical. The conditions for a spontaneous spin polarization in a quantum wire positioned in a zero magnetic.
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