다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

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.

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Spintronics: Fundamentals and applications

N G van Kampen 1981 Amsterdam: North-Holland xiv + 419 pp price Dfl 180 This is a book which, at a lower price, could be expected to become an essential part of the library of every physical scientist concerned with problems involving fluctuations and stochastic processes, as well as those who just enjoy a beautifully written book. It provides an extensive graduate-level introduction which is clear, cautious, interesting and readable.

https://iopscience.iop.org/article/10.1088/0031-9112/34/4/040/pdf

Stochastic Processes in Physics and Chemistry

The density-matrix renormalization group method (DMRG) has established itself over the last decade as the leading method for the simulation of the statics and dynamics of one-dimensional strongly correlated quantum lattice systems. In the further development of the method, the realization that DMRG operates on a highly interesting class of quantum states, so-called matrix product states (MPS), has allowed a much deeper understanding of the inner structure of the DMRG method, its further potential and its limitations. In this paper, I want to give a detailed exposition of current DMRG thinking in the MPS language in order to make the advisable implementation of the family of DMRG algorithms in exclusively MPS terms transparent. I then move on to discuss some directions of potentially fruitful further algorithmic development: while DMRG is a very mature method by now, I still see potential for further improvements, as exemplified by a number of recently introduced algorithms.

/pdf/the-density-matrix-renormalization-group-in-the-age-of-6718dr7b3l.pdf

The density-matrix renormalization group in the age of matrix product states

This tutorial review gives an elementary and self-contained derivation of the standard identities OwhOxUFh eif hOxU , etc.) for abelian bosonization in 1 dimension in a system of finite size L, following and simplifying Haldane's constructive approach. As a non-trivial application, we rigorously resolve (following Furusaki) a recent controversy regarding the tunneling density of states, r dos OwU, at the site of an impurity in a Tomonaga-Luttinger liquid: we use finite-size refer- mionization to show exactly that for ga 1 its asymptotic low-energy behavior is r dos OwUw. This agrees with the results of Fabrizio & Gogolin and of Furusaki, but not with those of Oreg and Finkel'stein (probably because we capture effects not included in their mean-field treatment of the Coulomb gas that they obtained by an exact mapping; their treatment of anti-commutation rela- tions in this mapping is correct, however, contrary to recent suggestions in the literature). — The tutorial is addressed to readers with little or no prior knowledge of bosonization, who are inter- ested in seeing ''all the details‚ explicitly; it is written at the level of beginning graduate students, requiring only knowledge of second quantization, but not of field theory (which is not needed here). At the same time, we hope that experts too might find useful our explicit treatment of certain subtleties that can often be swept under the rug, but are crucial for some applications, such as the calculation of rdosOwU - these include the proper treatment of the so-called Klein factors that act as fermion-number ladder operators (and also ensure the anti-commutation of different species of fermion fields), the retention of terms of order 1=L, and a novel, rigorous formulation of finite-size refermionization of both F eiFOxU and the boson field FOxU itself.

Bosonization for beginners — refermionization for experts

Coulomb-blockade phenomena and quantum fluctuations are studied in mesoscopic metallic tunnel junctions with high charging energies. If the resistance of the barriers is large compared to the quantum resistance, transport can be described by sequential tunneling. Here we study the influence of quantum fluctuations. They are strong when the resistance is small or the temperature is very low. A real-time approach is developed that allows the diagrammatic classification of resonant tunneling processes where different electrons tunnel coherently back and forth between the leads and the metallic island. With the help of a nonperturbative resummation technique we evaluate the spectral density, which describes the charge excitations of the system. From it, physical quantities of interest such as current and average charge can be deduced. Our main conclusions are as follows: An energy renormalization leads to a logarithmic temperature dependence of the renormalized system parameters. A finite lifetime broadening can change the classical picture drastically. It gives rise to a strong flattening of the Coulomb oscillations for low resistances, but in the Coulomb-blockade regime inelastic electron cotunneling persists. The effects become important at temperatures that are accessible in experiments.

Mesoscopic quantum transport : resonant tunneling in the presence of a strong coulomb interaction

We study resonant tunneling through a single-level quantum dot in the presence of strong Coulomb repulsion beyond the perturbative regime. The level is either spin degenerate or can be split by a magnetic field. Furthermore we discuss the influence of a bosonic environment. Using a real-time diagrammatic formulation, we calculate transition rates, the spectral density, and the nonlinear I-V characteristic. The spectral density shows a multiplet of Kondo peaks split by the transport voltage and the boson frequencies and shifted by the magnetic field. This leads to zero-bias anomalies in the differential conductance, which agree well with recent experimental results for the electron transport through single-charge traps. Furthermore, we predict that the sign of the zero-bias anomaly depends on the level position relative to the Fermi level of the leads. \textcopyright{} 1996 The American Physical Society.

Resonant tunneling through ultrasmall quantum dots: Zero-bias anomalies, magnetic-field dependence, and boson-assisted transport.

We study the Fano-Kondo effect in a closed Aharonov-Bohm (AB) interferometer which contains a single-level quantum dot and predict a frequency doubling of the AB oscillations as a signature of Kondo-correlated states Using the Keldysh formalism, the Friedel sum rule, and the numerical renormalization group, we calculate the exact zero-temperature linear conductance G as a function of the AB phase phi and level position epsilon In the unitary limit, G(phi) reaches its maximum 2e(2)/h at phi = pi/2 We find a Fano-suppressed Kondo plateau for G(epsilon) similar to recent experiments

Kondo correlations and the Fano effect in closed Aharonov-Bohm interferometers.

We study resonant tunneling through a quantum dot with one degenerate level in the presence of strong Coulomb repulsion and a bosonic environment. Using a real-time diagrammatic formulation we calculate the spectral density and the nonlinear current. The former shows a multiplet of Kondo peaks split by the transport voltage and boson frequencies. This leads to zero-bias anomalies in the differential conductance, which shows a local maximum or minimum depending on the level position. We compare with recent experiments.

/pdf/zero-bias-anomalies-and-boson-assisted-tunneling-through-1b67qhkxir.pdf

Herbert Schoeller

Papers

Bosonization for beginners — refermionization for experts

Mesoscopic quantum transport : resonant tunneling in the presence of a strong coulomb interaction

Resonant tunneling through ultrasmall quantum dots: Zero-bias anomalies, magnetic-field dependence, and boson-assisted transport.

Kondo correlations and the Fano effect in closed Aharonov-Bohm interferometers.

Zero-Bias Anomalies and Boson-Assisted Tunneling Through Quantum Dots