Реферат работы
«Spin resonance of electrons localized on Ge/Si quantum dots»
А. Ф. Зиновьева, А. В. Двуреченский, Н. П. Стёпина, А. С. Дерябин, А. И. Никифоров,
R. Rubinger, N. A. Sobolev, J. P. Leitao, M. C. Carmo.
Данная работа относится к новому актуальному направлению физики твёрдого тела – спинтронике, связанной с потенциальным применением спиновой степени свободы для создания устройств передачи и хранения информации, для квантовых вычислений. В работе изложены результаты исследования электронных состояний в структурах с Ge/Si квантовыми точками (КТ) методом ЭПР. Локализация электронов вблизи КТ реализована за счёт сложения деформационных полей в многослойных структурах с когерентными КТ и, как следствие, увеличения глубины потенциальной ямы для электрона в Si, окружающем Ge КТ, Обнаружен новый ЭПР-сигнал с аксиально-симметричным g-фактором (g||=1.9995, g=1.9984) и анизотропной шириной линии. Ось симметрии g-фактора совпадает с направлением роста квантовых точек. Главные значения полученного g-тензора совпадают со значениями g-тензора для электронов в Si в долине, а сам g-фактор имеет анизотропную угловую зависимость, что подтверждает локализацию электронов в напряженных областях Si вблизи Ge КТ. Минимальное значение ширины ЭПР-линии 0.8 Э наблюдается при ориентации внешнего магнитного поля вдоль оси роста квантовых точек, максимальное значение (в 4 раза больше) – в перпендикулярном направлении. Данный эффект может быть объяснен анизотропией процессов спиновой релаксации, связанной с существованием эффективного магнитного поля Бычкова-Рашба, возникающего вследствие структурной асимметрии Ge квантовой точки. До сих пор подобный эффект наблюдался только для двумерных (2D) асимметричных структур и связан с прецессионным механизмом спиновой релаксации при движении носителя в двумерном слое. В случае системы с КТ эффективное магнитное поле возникает при туннелировании носителей между квантовыми точками. В процессе туннелирования спин электрона поворачивается на малый угол, что приводит к перевороту спина после достаточного количества прыжков между КТ. Перенос заряда осуществляется преимущественно между близко расположенными КТ с сильной туннельной связью. Поскольку расположение КТ в плоскости носит случайный характер, то при каждом прыжке направление туннелирования меняется, что приводит к изменению направления эффективного магнитного поля. Частота прыжков между КТ может рассматриваться как характерная частота флуктуаций эффективного магнитного поля. Из анализа угловой зависимости ширины ЭПР-линии была получена характерная частота флуктуаций 1/с=3*1011с‑1. Данное значение и время поперечной спиновой релаксации T2=10-7c, полученное из ширины ЭПР-линии, позволили оценить величину эффективного магнитного поля HBR30 Э, что является верхним пределом данной величины.
Другие работы по теме:
Macro-microcosm substance space time quantum
I MUST DO MY DUTY During year 1999 I must pass to the peoples the novae knowledge about macro- and microcosm. Because of that in many respects will be depended on the fate civilization in the Third thousandth years. These knowledge will be passed by the brief portions in order to that specialists might arrive at a conclusion about of them truth.
Atomic Theory Essay Research Paper In ancient
Atomic Theory Essay, Research Paper In ancient Greek the word atom meant the smallest indivisible particle that could be conceived. The atom was thought of as indestructible; in fact, the Greek word for atom means “not divisible.” Knowledge about the size and make up of the atom grew very slowly as scientific theory progressed.
Covalent Bonds Essay Research Paper The first
Covalent Bonds Essay, Research Paper The first ionization energy IE1 is the energy required to remove the one electron from a gaseous atom. With this the effective nuclear charge increases and thus it takes more energy to remove the next electron. IE2 is always greater than IE1. Each subsequent electron becomes harder to remove.
Untitled Essay Research Paper Hydrogen bonds are
Untitled Essay, Research Paper Hydrogen bonds are extremely strong bonds which join molecules of relatively small mass. This peculiarity creates the unique properties associated with substances with hydrogen bonding, especially in H20. In most compounds, the polarity of its elements has a negligible effect on the dipole forces which connect them.
Van Der Waals And Permanent Dipole Forces
Essay, Research Paper Van der Waals forces Act between all atoms and molecules. Van der Waals forces are caused by the formation of temporary dipoles due to constant movement of electrons. The size of the force depends on the size of the molecule. In a
Atomic Theory Essay Research Paper ChemistryA Brief
Atomic Theory Essay, Research Paper Chemistry: A Brief History of Atomic Theory February 28, 1999 In the beginning of the 1800s John Dalton, an English scientist did work some work on gases, which lead him to the creation of a complex system of symbols for all known elements at the time. He took all the information he had collected, along with the Laws of Conservation of Mass, Definite Composition and Multiple Proportions and updated Aristotle’s theory of matter with the Atomic Theory of Matter, which stated: – All matter is composed of tiny, indivisible particles called atoms. – Atoms of an element have identical properties. – Atoms of different elements have different properties. – Atoms of two or more elements can combine in constant ratios to form new substances.
Bohr At The Rutherford Lab Essay Research
Paper Bohr at the Rutherford Lab Everyone at the time imagined the atom as a “plum pudding.” That is, it was roughly the same thing throughout, with negatively charged electrons scattered about in it like raisins in a pudding. As part of an experiment with x-rays in 1909, Rutherford was shooting a beam of alpha particles at a sheet of gold foil only 1/3000 of an inch thick, and tracing the particles’ paths.
Radiographic Technique And Interpretation Essay Research Paper
Production of x-rays requires training a stream of electrons produced at a methal cathode on a metal anode. As the electrons collide with atoms in the anode, they are stopped but their energy is released in two forms–mostly heat and a very small quantity (1%) as x-rays. The area ofthe cathode where the fast moving electrons collide is called the focal spot and is in fact the source of the x-rays.
Element Essay Research Paper What is an
Element Essay, Research Paper What is an element: Simple substances that can not be broken down into simpler substances. What is an atom: smallest part of an element that can be identified as an element.
Atoms Essay Research Paper The molecular structure
Atoms Essay, Research Paper The molecular structure hypothesis – that a molecule is a collection of atoms linked by a network of bonds – was forged in the crucible of nineteenth century experimental chemistry. It has continued to serve as the principal means of ordering and classifying the observations of chemistry.
Quantum Physics Essay Research Paper While researching
Quantum Physics Essay, Research Paper While researching quantum physics, I realized that I had just finished a book that was based on quantum theory. At the time, I didn t quite realize that quantum theory and quantum physics were related except in name. Niels Bohr once said, Anyone who is not shocked by quantum theory has not understood it.
Quantum Computer Essay Research Paper A Quantum
Quantum Computer Essay, Research Paper A Quantum Computer… a future technology By the strange laws of quantum mechanics, Folger, a senior editor at Discover, notes, an electron, proton, or other subatomic particle is “in more than one place at a time,” because individual particles behave like waves, these different places are different states that an atom can exist in simultaneously.
Bonding And Elements Essay Research Paper Element
Bonding And Elements Essay, Research Paper Element ? a substance which cannot be broken down into two or more substances by any means. Only contains one type of atom. Compound ? a substance in which atoms of two or
Niels Bohr Essay Research Paper October 21
Niels Bohr Essay, Research Paper October 21, 1998 Niels Bohr Niels Bohr was born in Copenhagen, he is the son of a physiology professor, and went to school at the University of Copenhagen, this is where he got his doctorate in 1911.
Resistance And Length Of Wire Essay Research
Paper IntroductionElectric charge on an object is often called static electricity. Objects charge up because they gain or lose electrons. The electron is the smallest part of the atom. The electron
Hydroelectric Power Essay Research Paper Kevin ShahPeriod
Hydroelectric Power Essay, Research Paper Kevin Shah Period 3 Hydroelectric Power One of the earliest ways to harness power is to use the powerful flow of water. On September 30th, 1882, in Appleton, Wisconsin, the first ever dam was built. Since then, over 2,044 billion-kilowatt hours have been produced each day, worldwide.
Transistors Essay Research Paper Semiconductors have an
Transistors Essay, Research Paper Semiconductors have an electrical resistivity that is in between those of good conductors and those of good insulators. Both silicon and germanium, which are the two basic semiconductors, have four electrons in the outermost electron subshell. In formation of the lattice structure of the silicon or germanium, all the valence electrons are involved in the bonding, so the material should be an insulator.
BoseEistein Condesation Essay Research Paper Everything in
Bose-Eistein Condesation Essay, Research Paper Everything in the world around us is made up of particles. These particles can be placed into two categories called bosons and fermions. Bosons are particles that have integer spin values, such as 1, 2, 3 and so on.3 Examples of bosons are photons, which are quantum of electromagnetic radiation, phonons, which are quantum of vibrational energy, and most atoms.
Investigating The Effect Of Resistance On Wires
Essay, Research Paper I am going to be studying the resistance of wire. The purpose of this investigation is to see how length and thickness of wire affect the dependent variable, resistance. Prediction
Religion And The Changes Through The Years
Essay, Research Paper Overview: Physics of Magnetic Resonance Microscopy Magnetic resonance microscopy (MRM) is founded on the same physical principles as its clinical cousin, magnetic resonance imaging (MRI). Two crucial discoveries have made MRI possible. The 1952 Nobel Prize in Physics was awarded to Felix Bloch of Stanford and Edward M.
Nuclear Magnetic Resonance Essay Research Paper The
Nuclear Magnetic Resonance Essay, Research Paper The measurement of nuclear and electron magnetic resonance on bulk materials was made possible by Felix Bloch and Edward Purcell and in 1952 they shared the Nobel Prize in Physics for their work. Until then, magnetic resonance was a measurable phenomena in which atoms were shot through a magnet as a beam.
Photoelectric Effect Essay Research Paper Photoelectric EffectPhotoelectric
Photoelectric Effect Essay, Research Paper Photoelectric Effect Photoelectric Effect is the formation and liberation of electrically charged particles in matter, usually metals, when it is irradiated by light or other electromagnetic radiation. The term photoelectric effect designates several types of interactions.
Photosynthesis Essay Research Paper PHOTOSYNTHSIS INFORMATION The
Photosynthesis Essay, Research Paper PHOTOSYNTHSIS INFORMATION: The Nature of Light Light behaves both as a wave phenomenon and as discrete particles of energy called photons. If we look at light as a wave phenomenon, we can assign it a wavelength (the distance from one peak of the wave to the next) and an amplitude (the distance the wave oscillates from its centerline).
Untitled Essay Research Paper Yazan Fahmawi
Untitled Essay, Research Paper Yazan Fahmawi T3 IBS Chemistry Ms. Redman Historical Development of Atomic Structure The idea behind the "atom" goes back to the Ancient Greek society, where
Ratio Of Charge To Mass For The
Electron Essay, Research Paper Introduction: The object of this lab was to determine the measure of the ratio of an electron to its mass. This is done by accelerating a stream of electrons through a measured potential difference. The stream of electrons moves through a uniform magnetic field. It is perpendicular to the velocity of the electrons.
Super Conductors Essay Research Paper I INTRODUCTION
Super Conductors Essay, Research Paper I. INTRODUCTION: Superconductors An element or compound that will conduct electricity without resistance below acertain temperature is a superconductor. This applies only to direct current electricity andto limited amounts of current. Once it is set in motion the current will flow forever, in aclosed loop of superconducting material.
Electron Transport Essay Research Paper Electron Transport
Electron Transport Essay, Research Paper Electron Transport Essay Electron transport is the last phase and most important phase of cell respiration. It accounts for most of the ATP made in cell respiration. Cell respiration makes a total of thirty eight ATP?s, two from Glycolysis, two from the Krebs cycle and thirty four from electron transports.
Discovery Of The Electron Essay Research Paper
The Discovery Of The Electron The electron was discovered in 1895 by J.J. Thomson in the form of cathode rays, and was the first elementary particle to be identified. The electron is the lightest known particle which
Microscopes And Electron Micro Essay Research Paper
Microscopes and Electron Microscopy There are many different types of microscopes and each of them works in different ways and are used to magnify different things. Some examples of these are light microscopes, transmission electron microscopes and scanning electron microscopes.