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Spin-½

About: Spin-½ is a research topic. Over the lifetime, 40423 publications have been published within this topic receiving 796639 citations.


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TL;DR: The string-net picture has been used to make artificial photons, artificial electrons, and artificial quarks and gluons in condensed-matter systems as discussed by the authors, and it has been shown that these new phases of matter have the unusual property that their collective excitations are gauge bosons and fermions.
Abstract: Recent advances in condensed-matter theory have revealed that new and exotic phases of matter can exist in spin models (or more precisely, local bosonic models) via a simple physical mechanism, known as ``string-net condensation.'' These new phases of matter have the unusual property that their collective excitations are gauge bosons and fermions. In some cases, the collective excitations can behave just like the photons, electrons, gluons, and quarks in our vacuum. This suggests that photons, electrons, and other elementary particles may have a unified origin---string-net condensation in our vacuum. In addition, the string-net picture indicates how to make artificial photons, artificial electrons, and artificial quarks and gluons in condensed-matter systems.

152 citations

Journal ArticleDOI
TL;DR: In this article, the authors discuss the collision between two particles possessing spin, such as electrons, and also between two without spin particles such as α-particles, and deduce from the symmetry properties of the wave functions a scatter-ing law differing considerably from the classical.
Abstract: It is well-known that the problem of the collision between two particles interacting according to the inverse square law is exactly soluble on the wave mechanics, and that the solution yields the same scattering laws as the classical theory. If, however, the two particles are identical, e.g. , two electrons or two α-particles, this is not necessarily the case; for the wave functions used must be antisymmetrical or symmetrical in the co-ordinates of the two particles; and this may affect the scattering laws. In this paper we shall discuss the collision between two particles possessing spin, such as electrons, and also between two particles without spin, such as α-particles. Assuming an inverse square law force between the particles, and neglecting the actual spin forces, we shall deduce from the symmetry properties of the wave functions a scatter­ing law differing considerably from the classical. We shall also mention the various methods by which the effect could be observed, and give some experi­mental evidence in its favour. The application of the exclusion principle to collision problems has been discussed by the author in a previous paper. Suppose we wish to describe the motion of two particles interacting in any field of force. We obtain a solution w (r1 r2) of the wave equation, where r1 refers to the position of the first particle, and r2 to that of the second. If we did not use antisymmetrical wave functions, we should argue that the probability that the first particle should be at r1 and the second at r 2 would be | w (r1 r2)|2, and therefore the probability that one particle should be at r1 and the other at r2 would be | w (r1 r2)|2 + | w (r2 r1)|

152 citations

Journal ArticleDOI
TL;DR: It is pointed out that persistent current measurements in a closed ring provide a conceptually simple way of detecting this fundamental length scale of the Kondo effect.
Abstract: A fundamental prediction of scaling theories of the Kondo effect is the screening of an impurity spin by a cloud of electrons spread out over a mesoscopic distance. This cloud has never been observed experimentally. Recently, aspects of the Kondo effect have been observed in experiments on quantum dots embedded in quantum wires. Since the length of the wire may be of order the size of the screening cloud, such systems provide an ideal opportunity to observe it. We point out that persistent current measurements in a closed ring provide a conceptually simple way of detecting this fundamental length scale.

152 citations

Journal ArticleDOI
TL;DR: In this article, a variational formulation of the time-dependent linear response based on the Sternheimer method is developed in order to make practical ab initio calculations of dynamical spin susceptibilities of solids.
Abstract: A variational formulation of the time-dependent linear response based on the Sternheimer method is developed in order to make practical ab initio calculations of dynamical spin susceptibilities of solids. Using gradient density functional and a muffin-tin-orbital representation, the efficiency of the approach is demonstrated by applications to selected magnetic and strongly paramagnetic metals. The results are found to be consistent with experiment and are compared with previous theoretical calculations.

151 citations

Journal ArticleDOI
TL;DR: In this paper, the authors examined the relationship between the spin exchange parameter J and the energy difference between the broken-symmetry and highest-spin states of the spin dimer on the basis of spin-Hamiltonian.
Abstract: For a general spin dimer that has different numbers of unpaired electrons at the two spin sites, we examined the relationship between the spin exchange parameter J and the energy difference between the broken-symmetry and highest-spin states of the spin dimer on the basis of the spin-Hamiltonian Ĥ=−JŜ1⋅Ŝ2. The resulting relationship was shown to be a generalization of Noodleman’s formulas derived from the broken-symmetry method within density functional theory. We proposed a new method of calculating spin exchange parameters J within density functional theory on the basis of Slater’s transition state concept. The intrachain J values of magnetic solids A2MnF5 (A=Rb, Cs, NH4, Na, Li) were calculated by using the “transition-state” and Noodleman’s methods. The J values calculated by the transition-state method are in much better quantitative agreement with experiment.

151 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202234
20212,352
20201,787
20191,748
20181,696
20171,621