点击次数：

COLLOQUIA & SEMINARS 2009:
 

1. (SEMINAR)"LDA+DMFT method and its application in investigation of magnetic properties", Associate Prof. Dr. Xian-Gang Wan (Nanjing University), at 4:00 pm, March 17, 2009.

1. Abstract:
   LDA+DMFT is a very useful method for correlated system. In this talk, I will discuss several application of this method: 1) An efficient method to compute magnetic exchange interactions in systems with strong correlations is introduced; 2) We calculate the many-body electronic structures of several Mott insulating oxides including undoped high Tc materials; 3) We discuss the competition between RKKY interaction and Kondo effect in PuAm alloy; 4) We study the long-range exchange interaction in high Tc materials.

2. (COLLOQUIUM)"Optical activity of chiral planar nanostructures", Prof. Dr. Yuri Svirko (University of Joensuu, Joensuu, FINLAND), at 4:00 pm, March 23, 2009.

1. Abstract:
   Advances in nano- and microscale fabrication make possible artificial materials with extraordinary optical properties such as photonic crystal slabs and waveguides with ultraslow speed of light or ¡°left-handed¡± metamaterials. Planar nanostructures, which can be easily fabricated by electron-beam lithography, are currently attracting a special interest of the research community. The important challenge in tailoring optical properties of planar nanostructures is polarization control, which would be crucial for a number of applications. The pronounced changes in the polarization state of transmitted light wave can be achieved with chiral nanogratings, e.g. by using an ordered array of chiral nanoparticles much thinner than wavelength. Optical properties of metal nanogratings are governed by surface plasmons, i.e. by collective oscillation of conduction electrons in metal nanoparticles. We demonstrated that chiral metal gratings exhibit giant optical activity with specific rotation of about 104 0†2/mm in the vicinity of the surface-plasmon resonance. Such a strong polarization effect in a thin quasi-two-dimensional object originates from the coupling of surface plasmons at the metal-dielectric and metal-vacuum interfaces of the chiral grating. However, in metal nanostructures, optical losses impose severe restrictions on photonic applications. This difficulty can be partially overcome using an all-dielectric chiral photonic crystal that surpasses metal nanogratings in terms of the rotation power and transparency. In the planar chiral photonic crystal, a dramatic enhancement of the optical activity originates from the coupling of the normally incident light wave with low-loss waveguide modes. We anticipate that the strong optical activity of chiral nanostructures will open new opportunities in polarization control for light emitters, polarization selective photo-sensors and polarization switching devices.

3. (SEMINAR)"Unsymmetric spin-orbit coupling in single-walled carbon nanotubes", Prof. Dr. Jin-Ming Dong (Nanjing University), at 10:00 am, March 31, 2009.

1. Abstract:
   The spin-orbit coupling (SOC) of single-walled carbon nanotube (SWNT) has been studied using both the first-principles and tight-binding methods. It is found that the curvature-induced ¦Ò - ¦Ð coupling in the SWNTs always causes a more strong SOC in their ¦Ð bonding states than their ¦Ð* anti-bonding ones. And a microscopic mechanism has been proposed to satisfactorily explain the experimental observation that the SOC- induced band splitting in the SWNTs is different for electrons and holes [Nature 452, 448 (2008)], which can not be accounted for by the present theories. Finally, a SOC's family behavior of the SWNTs is also found, showing that their SOC depends on both the tube's chirality and family type.

4. (SEMINAR)"Aspects of Spin Dynamics in Bulk Semiconductors and in Magnetic Multilayers", Prof. Dr. H. C. Schneider (Technische Universitaet Kaiserslautern, GERMANY) at 4:00 pm, April 1, 2009.

1. Abstract:
   I present theoretical results obtained in my group on ultrafast spin dynamics of holes and electrons in bulk GaAs. The spin-dependent carrier dynamics is computed by solving dynamical equations for the spin-density matrix containing Boltzmann-type scattering integrals, which include carrier-carrier Coulomb scattering, phonon scatterin, and impurity scattering. The influence of excitation conditions and doping on the spin dynamics and spin relaxation times is discussed. A comparison with experiments is also provided.
   If time permits, I will also discuss a macroscopic description of spin transport through magnetic multilayers, which allows one to extract a well-defined signal propagation velocity for a modulated (or switched) spin current. Our approach shows that dynamical spin transport through magnetic multilayers possesses both diffusion and wave characteristics. The latter allow one to define the signal propagation velocity and lead to deviations from a diffusive behavior for high-frequency modulation.

5. (SEMINAR)"Transport and spin properties of the two-dimensional electron gas in GaN-based heterostructures", Prof. Dr. Bo Shen (Beijing University) at 4:00 pm, April 3, 2009.

1. Abstract:
   GaN-based heterostructures are of special interests for the fabrication of high electron mobility transistors (HEMTs) for high power, high temperature and high frequency applications. Owing to the strong spontaneous and piezoelectric polarizations in III-nitrides, the polarization-induced electric field at an AlxGa1-xN/GaN heterointerface is as high as ~ MV/cm. This leads to a significant increase of the sheet density and the narrower confinement of the two-dimensional electron gas (2DEG) in an AlxGa1-xN/GaN heterostructure in comparison with that in an AlxGa1-xAs/GaAs one. Due to the much deeper triangular quantum well and the much higher 2DEG density at AlxGa1-xN/GaN heterointerfaces, the subband structures, the transport properties of the 2DEG and other properties in AlxGa1-xN/GaN heterostructures are probably different from those in AlxGa1-xAs/GaAs ones. On the other hand, GaN-based semiconductors are the potential candidates for spintronics because of the long spin relaxation time in these materials which can persist to room temperature. Although the spin-orbit coupling parameter is thought to be small in wide band-gap semiconductors, the strong polarization-induced electric field in AlxGa1-xN/GaN heterostructures may enhance the spin-orbit interactions. Therefore, the spin properties, especially the spin-orbit interaction, of the 2DEG in GaN-based heterostructures are necessary to be further understood for their potential application in spintronics. Magneto-transport measurement is powerful to understand the transport properties of the 2DEG in semiconductor heterostructures. In this study, based on the growth of AlxGa1-xN/GaN heterostructures of high quality by means of metal organic chemical vapor deposition (MOCVD), the fine subband structures and the 2DEG occupation, the magneto-intersubband scattering (MIS) effect of the 2DEG, the effective mass of the 2DEG, and the zero-field spin splitting of the 2DEG in AlxGa1-xN/GaN heterostructures have been studied in detailed. Meanwhile, the circular photo-galvanic effect (CPGE) induced by the spin-orbit interactions of the 2DEG in AlxGa1-xN/GaN heterostructures has also been investigated.

6. (COLLOQUIUM)"Intrinsic symmetry breaking", Prof. Xin Sun (Fudan University) at 4:00 pm, April 17, 2009.
   

7. (SEMINAR)"Unconventional charge and spin density waves", Prof. Dr. Dong-Lai Feng (Fudan University) at 9:00 am, April 28, 2009.

1. Abstract:
   Charge and spin density waves (CDW and SDW) are two basic forms of order in solid, and have been one of the focus in condensed matter physics. In our study of various density wave systems, we found their microscopic mechanisms are often unconventional. In this talk I will give several examples about the rich and anomalous density waves in complex materials.
   1. The Transition Metal Dichalcogenides (TMD) compound with 2H structure is the first system in which two dimensional Charge Density Wave (CDW) is discovered. However it had puzzles people for nearly 30 years that it can be explained neither by the Fermi surface nesting scenario, nor the saddle point scenario. We measured the electronic structure of 2H-NaxTaS2 and NbSe2 and proved that the CDW is not related to the Fermi Surface but to the ¡°Fermi Patch¡± region all over the Brillion zone. This new mechanism could explain the charge instability in many strongly coupled systems
   2. Chinese scientists contribute a lot in the development of iron-arsenic based high temperature superconductor since its discovery in the year of 2008. Similar to the cuprate, there are coexistence of magnetic order and superconductivity in the iron-based systems; the mechanism of its itinerant magnetic ordering calls for further investigation. Normally itinerant magnetic ordering is induced by the Fermi surface nesting while we find in materials such as BaFe2As2 the Spin Density Wave is caused by the exchange splitting , moreover the coexistence of superconductivity and SDW is discovered in Sr0.8K0.2Fe2As2.

8. (SEMINAR)"Femtosecond ultrafast nonlinear magneto-optical study for spintronic materials", Researcher Dr. Xin-Hui Zhang (Institute of Semiconductors), at 9:00 am, May 8, 2009.

1. Abstract:
   The ultrafast dynamics of spin and magnetization in semiconductor nanostructures and ferromagnetic semiconductor heterostructures have been under investigation by employing time-resolved ultrafast linear and nonlinear magneto-optics. In this talk, I will briefly introduce some experimental studies we are doing now or trying to do in near future. These include: 1) spin relaxation and dephasing as well as ultrafast magnetization manipulation in GaMnAs and III-V group low dimensional materials based on time-resolved Kerr rotation (TR-MOKE) and photoluminescence (TR-PL) techniques; 2) interfacial spin dynamics of spin-injection-based heterostructures such as Fe/GaAs, MnAs/GaAs, GaMnAs/GaAs, by using the magnetic field enhanced second harmonic generation technique (MSHG); 3) Spin diffusion and relaxation manipulation in III-V and IV-group two dimensional electron gas (2DEG) through control of spin-orbital coupling; studying huge anisotropic spin relaxation and searching for spin helix, based on the transient spin grating technique.

9. (COLLOQUIUM)"Towards semiconductor spintronics devices", Prof. Dr. Wei-Kun Ge (Tsinghua University and SunYat Sin University), at 4:00 pm, May 8, 2009.

1. Abstract:
   An InGaAs quantum well was made as a 2DEG (two dimensional electron gas) with structure inversion asymmetry (SIA). Rashba spin-orbit coupling in such a system was revealed by Shubnikov-de Haas (SdH) oscillation from its beating pattern. Current in the plane of the 2DEG can induce electron spin polarization oriented perpendicular to the current direction, and the spin can be detected by Kerr effect. That is a possible way of creating spin polarization in a semiconductor without either applying magnetic field, or using dilute magnetic materials.
   Such current induced electron spin polarization can be further taken as an approach to create spin source for a spintronic device. Furthermore, we have achieved converting a spin current in such a Rashba system into a measurable electric current, which is of great importance in spin detection or making the drain for a spin FET, as proposed by Datta & Das.
   Other approaches relevant to spintroincs devices by using asymmetric spin relaxation in a Rashba system, or using spin filter in a Dresslehaus system, will also be discussed.

10. (SEMINAR)"Ultrafast dynamics of an atom in femtosecond laser pulses", Prof. Dr. Jian-Min Yuan (National University of Defense Technology), at 4:00 pm, May 27, 2009.

1. Abstract:
   THz emission of atoms in intense femtosecond Gaussian-enveloped laser pulses is investigated by solving time-dependent Schrödinger and Dirac equations (TDSE). It is deduced from the one-component laser field that the excitations of electron to the continuum and high Rydberg states are essential for the THz emissions. Upon this conclusion, an alternative description of the four-photon process is proposed to explain the significant enhancement of THz emissions by mixing the fundamental and its second order harmonic laser fields. This mechanism is confirmed with the help of a short-range shallow potential model. Besides, a biased electric field is also used to destroy the symmetry of the atomic system such that three-photon processes dominate in this situation. Finally a 5THz frequency laser field is superposed on the fundamental laser field to induce the generation of second harmonics which may involve both the three-and four-photon photon process discussed in the present study.

11. (SEMINAR)"Quantum dissipation and quantum transport", Prof. Dr. Yi-Jing Yan (University of Science and Technology of Hong Kong), at 4:00 pm, June 2, 2009.

1. Abstract:
   We have recently developed a hierarchical equations-of-motion (HEOM) approach to nonperturbative and non-Markovian quantum dissipation. It is a unified and exact theory for arbitrary coupling Gaussian environments of distinct nature: bosonic versus fermionic, and canonical versus grand canonical ensembles. It admits also an arbitrary time-dependent external field driving. Two systems will be used to elaborate both the formulation and implementation aspects of the theory. In an electron transfer (ET) system, the bath environment serves as a canonical bosonic ensemble, responsible for the system decoherence and energy relaxation. In a quantum transport setup, each electrode reservoir serves as a grand canonical fermion ensemble. It is responsible not only for decoherence and energy relaxation, but also for the fermion particle (i.e., electron) transport in/out of the system. The HEOM-based quantum transport theory will be summarized, together with the calculated transient currents through model quantum dot systems.

12. (SEMINAR)"Spin transport and magnetization dynamics in conducting ferromagnets", Prof. Dr. S. F. Zhang (University of Arizona, USA), at 4:00 pm, June 26, 2009.

1. Abstract:
   There are quite numbers of spin-dependent phenomena developed in the last several years for transition-metal ferromagnetic metals. Among them, current-driven spin torques, spin pumping, spin electromotive force, and inhomogeneous spin damping have received considerable attention. We show that these seemingly different phenomena can be understood and formulated within a single scheme. New predictions such as inhomogeneous damping tensors are explicitly made.

13. (SEMINAR)"Imaging of energy eigenstate of Quantum dot", Prof. Dr. Zhao-Zhong Wang (Laboratoire de Photonique et de Nanostructures, CNRS, FRANCE), at 4:00 pm, August 4, 2009.

1. Abstract:
   Due to their important technological applications, such as low-threshold lasers, nanometer scaled memories or single photon sources and detectors etc, semiconductor Quantum Dots (QDs) have attracted an enormously interest in recent years. Imaging of energy eigenfunction in semicond uctor Quantum Dots (QD) by STM for cleaved InAs/GaAs QDs or uncapped InAs/GaAs QDs offers a unique opportunity to investigate the properties of QDs. In this communication, we report on cross-sectional Scanning Tunneling Microscopy and Spectroscopy and subsequent electronic wave-function imaging at low temperature (T=77 K) on cleaved In(Ga)As/GaAs QDs. The Sample, consisted of four arrays of QDs separated by 40nm highly Beryllium doped GaAs spacers, was grown by Molecular Beam Epitaxy on GaAs(100) substrate. Self assembled In(Ga)As QDs are formed by the deposition of a 2.0 ML (monolayer) of InAs at 500°C. After slicing the array of QDs by cleavage, Cross-Sectional STM experiment reveals numerous dots with different lateral base lengths but quite uniform height. Spatially resolved Scanning Tunneling Spectroscopy (STS) are subsequently measured on a series of selected individual dots with different lateral size. At positive voltage, the dI/dV spectra measured by STS exhibit a set of discrete and well-defined peaks in the unoccupied QDs state. Furthermore, differential conductance dI/dV maps display clearly the real space spatial variation of the electron wavefunctions for the successive ground state and excited states. The images, recorded at specific voltages corresponding to the QD eigenvalue, strikingly match to the well-known atomic wave-function. These experimental results have recently initiated a simulation study performed in the frame of the envelope function approximation and k.p multibands formalism to calculate the energy level and wavefunction in cleaved quantum dots.

14. (SEMINAR)"Novel Magnetoelectric Effects: Current-Driven Domain Wall Dynamics and Inverse Spin Hall Effect", Asso. Prof. Dr. G. Tatara (Department of Physics, Tokyo Metropolitan University, JAPAN), at 4:00 pm, September 4, 2009.

1. Abstract:
   Present information technology is based on electron transport and magnetism. Magnetism has been most successful in high-density storages such as hard disks. For integration of magnetic storages into electronic circuits, mechanisms are necessary to convert electric current/voltage into magnetic information and vice versa. The most common and oldest electro-magnetic coupling is the one arising from Maxwell's equations. Ampere's law or Oersted's law, discovered in the early nineteenth century, describes the magnetic field created by an electric current, and the Faraday's law provides us means to convert magnetic information into electric current or voltage. In the talk, novel magnetoelectric effects in solids are discussed. They arise from the quantum mechanical sd interaction, and have higher efficiency in small systems than the Maxwell's mechanism. The first is the current-induced magnetization switching[1], and the second is the generation of electric current by magnetization dynamics (the inverse spin Hall effect)[2-4].
   
   References:
   [1] G. Tatara, H. Kohno and J. Shibata, Phys. Rep. 468, 213 (2008).
   [2] E. Saitoh et al., Appl. Phys. Lett. 182509 (2006).
   [3] J. Ohe, A. Takeuchi and G.Tatara, Phys. Rev. Lett. 99, 266603 (2007).
   [4] A. Takeuchi,G. Tatara, J. Phys. Soc. Jpn. 77, 074701 (2008).

15. (SEMINAR)"Physics with spin in semiconductors: Two recent results", Prof. Dr. Daniel Haegele (Department of Physics and Astronomy, Ruhr-University Bochum, GERMANY), at 4:00 pm, September 8, 2009.

1. Abstract:
   In the last decade, the large field of semiconductor spin physics has proven fruitful for new interesting physics.
   In the first part of my talk I present a new approach to the old problem of Bose-Einstein-Condensation of semiconductor excitons. The new approach utilizes partly spin polarized excitons for revealing an - otherwise invisible - fingerprint of a degenerate gas of excitons and biexcitons on its route to condensation. We theoretically predict, that the photoluminescence polarization at the biexciton line turns from unpolarized before condensation to highly polarized in the case of a condensate. Preliminary measurements show indeed an onset of circular polarization at the biexciton emission line in ZnSe and GaAs quantum wells when conditions for condensation are approached at high carrier densities and low temperatures.
   In the second part of my talk I give a short heuristic derivation of anisotropic spin relaxation rates and present recent measurements of the spin relaxation tensor in bulk n-GaN.

16. (SEMINAR)"Topological insulators in Bi2Se3, Bi2Te3 and Sb2Te3 with a single Dirac cone on the surface", Researcher Dr. Xi Dai (Institute of Physics, CAS), at 4:00 pm, September 17, 2009.

1. Abstract:
   Topological insulators are new states of quantum matter in which surface states residing in the bulk insulating gap of such systems are protected by time-reversal symmetry. The study of such states was originally inspired by the robustness to scattering of conducting edge states in quantum Hall systems. Recently, such analogies have resulted in the discovery of topologically protected states in two-dimensional and three-dimensional band insulators with large spin¨Ãorbit coupling. So far, the only known three-dimensional topological insulator is BixSb1?x, which is an alloy with complex surface states. Here, we present the results of first-principles electronic structure calculations of the layered, stoichiometric crystals Sb2Te3, Sb2Se3, Bi2Te3 and Bi2Se3. Our calculations predict that Sb2Te3, Bi2Te3 and Bi2Se3 are topological insulators, whereas Sb2Se3 is not. These topological insulators have robust and simple surface states consisting of a single Dirac cone at the 0 point. In addition, we predict that Bi2Se3 has a topologically non-trivial energy gap of 0.3 eV, which is larger than the energy scale of room temperature. We further present a simple and unified continuum model that captures the salient topological features of this class of materials.

17. (SEMINAR)"Understanding molecular crystals under high pressures", Prof. Dr. Tian Cui (Jilin University) at 4:00 pm, October 27, 2009.

1. Abstract:
   In 1935, Wigner and Huntington predicted that molecular hydrogen would undergo a transition from a proton-paired insulator to a monatomic metal under sufficiently strong compression, but up to now there are no direct and convincing experimental observations of metallic hydrogen in solid form. Remarkable progress has been taken in the study of other molecular solids at high density, especially for diatomic molecular crystals and hydrogen-rich systems, which includes the observation of pressure induced metallic transition, molecular dissociation, and atomic phase. However there are still some puzzles unresolved. Here I present our recent researches on the behavior of some typical molecular solids under high pressure.

18. (SEMINAR)"Spin transport in FM/monolayer molecule nanoparticles", Prof. Dr. Di Wu (Nanjing University), at 4:00 pm, October 29, 2009.

1. Abstract:
   Spintronics has attracted much scientific and technological interest in recent years. The hybrid devices which integrate spin-dependent effect into semiconductors or organic materials are proposed. Organic materials such as small molecules and polymers are believed to have long spin coherence due to the weak spin-orbit interaction and hyperfine interaction. Recently we have studied the spin transport through molecules using self-assembled monolayers(SAMs) of molecules on half metallic Fe3O4 nanoparticles. The magnetoresistance (MR) of molecule fully covered nanoparticles is up to 7.3% at room temperature, which is more than two times larger than that of pure Fe3O4 nanoparticles. By varying the length of the molecules from about 0.8 nm to 2 nm, the resistance increases exponentially. However the MR almost keeps constant, indicating the spin scattering is weak in molecules and spin diffusion length is estimated to be much larger than 4 nm at room temperature. These results show that small molecules are promising for development of future spin-based molecular electronics. Finally, the spin transport mechanism in molecules will be discussed in this talk.

19. (SEMINAR)"Proper Scaling of the Anomalous Hall Effect", Prof. Dr. Xiao-Feng Jin (Fudan University), at 4:00 pm, November 16, 2009.

1. Abstract:
   The anomalous Hall effect is one of the most prominent phenomena existing in magnetic materials. It has remained unsolved for more than a century because its rich phenomenology defies the standard classification methodology, prompting conflicting reports claiming the dominance of various processes. Working with epitaxial films of Fe, we succeeded in independent controls of different scattering processes through temperature and layer thickness. The resulting data appropriately accounted for the role of phonons, thereby clearly exposing the fundamental flaws of the standard plot of the anomalous Hall resistivity versus longitudinal resistivity. A new scaling has been thus established that allows an unambiguous identification of the intrinsic mechanism as well as the extrinsic mechanisms of the anomalous Hall effect.

20. (COLLOQUIUM)"Actively Controllable Properties of Terahertz Metamaterials and Their Applications", Dr. Hou-Tong Chen (Los Alamos National Laboratory, USA), at 4:00 pm, November 23, 2009.

1. Abstract:
   Planar metamaterials have been designed, fabricated, modeled and characterized at terahertz (THz) frequencies, which is one of the most technically challenging and least developed regime in the electromagnetic spectrum. Their resonant properties derive from the structural geometry and dimensions of the split-ring resonators serving as the metamaterial basic building blocks. By incorporating natural materials, e.g. semiconductors, as the metamaterial substrates or in the critical regions of the metamaterial elements, the metamaterial resonant properties can be dynamically or actively controlled through external stimuli, such as photoexcitation and voltage bias. We demonstrated all optical switching of THz radiation through photoexcitation of the metamaterial semiconducting substrate, e.g. intrinsic GaAs wafers or GaAs:ErAs nanoisland superlattices. In the latter case the carrier lifetime can be engineered from sub-picosecond to tens of picoseconds, which determines the ultrafast switching time of the THz radiation. More interestingly, when fabricating the planar metamaterials on a semiconducting substrate with a thin doping layer, the metamaterial resonant response can be actively switched through the application of a voltage bias, due to the voltage-controlled depletion near the split gaps. The solid-state metamaterial devices operate at room temperature and are capable of state-of-the-art performance in electrical modulation of THz intensity and phase, which are correlated and further enable a broadband modulation of impulsive THz radiation in the time domain measurements. I will also discuss other recent progress from our team in THz metamaterials and devices, including frequency agile metamaterials, metamaterial antireflection coating, and superconductor metamaterials.

21. (SEMINAR)"Terahertz Generation, Detection and phase modulation in Periodically Poled Lithium Niobate", Prof. Dr. G. H. Ma (Shanghai University), at 4:00 pm, November 27, 2009.

1. Abstract:
   In past decades, extensive efforts have been focused on terahertz wave generation, transportation and detection, little was done on control and manipulation of THz radiation. In fact, techniques to control and manipulate THz wave (for example, amplitude and phase modulation, frequency filtering etc) are also important for the practical application of THz wave in future. Ultrafast photonics group in shanghai university focused on THz wave generation and coherent control. We develop two methods to manipulate the THz wave, one is active control, and the other is passive control. In this talk, I would like to introduce our study on the THz wave active control: THz generation and phase modulation in periodically poled lithium niobate (PPLN) crystal; we demonstrate the observation of magnetic field induced THz wave phase flip in photorefractive PPLN crystal. After that, I would like to introduce our preliminary results on the passive control on THz wave: By designing proper structure, we can realize THz wave antireflection, frequency filtering etc.
   

22. (SEMINAR)"Two-dimensional electron gas with spin-orbit disorder", Prof. Dr. E. Ya. Sherman (Universidad del Pais Vasco and IKERBASQUE Basque Foundation for Science, Bilbao, SPAIN), at 4:00 pm, December 7, 2009.

1. Abstract:
   Inevitable disorder in spin-orbit coupling is an important feature of real low-dimensional electron structures. Here the spin-orbit disorder plays an important or the crucial role: (i) Si/Ge quantum wells, (ii) spin helix patterns, (iii) GaAs (011) quantum wells, and (iv) graphene.
   We study theoretically two main manifestations of the spin-orbit disorder. First one is the spin relaxation, which can occur even without momentum relaxation. We show that in a high-mobility electron gas subject to a magnetic field the spin-orbit randomness leads to a spin memory effect and to a fast Gaussian rather than a simple exponential spin relaxation.
   The other manifestation is the abilities of spin manipulation. Due to the disorder in spin-orbit coupling, a time-dependent external electric field generates a spatially random spin-dependent perturbation. Even for a very weak disorder, at typical experimental conditions the efficiency of the induced electric dipole spin resonance can be very high. In addition, spin-flip transitions lead to considerable corrections to the Drude conductivity, which can be observed experimentally. These effects can be important for possible applications in spintronics.