Spin-½

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

Quantum mechanics without probability amplitudes

Abstract: First steps are taken toward a formulation of quantum mechanics which avoids the use of probability amplitudes and is expressed entirely in terms of observable probabilities. Quantum states are represented not by state vectors or density matrices but by “probability tables,” which contain only the probabilities of the outcomes of certain special measurements. The rule for computing transition probabilities, normally given by the squared modulus of the inner product of two state vectors, is re-expressed in terms of probability tables. The new version of the rule is surprisingly simple, especially when one considers that the notion of complex phases, so crucial in the evaluation of inner products, is entirely absent from the representation of states used here.

Spin-torque generator engineered by natural oxidation of Cu.

Abstract: The spin Hall effect is a spin-orbit coupling phenomenon, which enables electric generation and detection of spin currents. This relativistic effect provides a way for realizing efficient spintronic devices based on electric manipulation of magnetization through spin torque. However, it has been believed that heavy metals are indispensable for the spin-torque generation. Here we show that the spin Hall effect in Cu, a light metal with weak spin-orbit coupling, is significantly enhanced through natural oxidation. We demonstrate that the spin-torque generation efficiency of a Cu/Ni81Fe19 bilayer is enhanced by over two orders of magnitude by tuning the surface oxidation, reaching the efficiency of Pt/ferromagnetic metal bilayers. This finding illustrates a crucial role of oxidation in the spin Hall effect, opening a route for engineering the spin-torque generator by oxygen control and manipulating magnetization without using heavy metals.

Observation of a Time Quasicrystal and Its Transition to a Superfluid Time Crystal.

Abstract: We report experimental realization of a quantum time quasicrystal and its transformation to a quantum time crystal We study Bose-Einstein condensation of magnons, associated with coherent spin precession, created in a flexible trap in superfluid ^{3}He-B Under a periodic drive with an oscillating magnetic field, the coherent spin precession is stabilized at a frequency smaller than that of the drive, demonstrating spontaneous breaking of discrete time translation symmetry The induced precession frequency is incommensurate with the drive, and hence, the obtained state is a time quasicrystal When the drive is turned off, the self-sustained coherent precession lives a macroscopically long time, now representing a time crystal with broken symmetry with respect to continuous time translations Additionally, the magnon condensate manifests spin superfluidity, justifying calling the obtained state a time supersolid or a time supercrystal

Effective Spin-Mixing Conductance of Heavy-Metal-Ferromagnet Interfaces.

Abstract: The effective spin-mixing conductance (G_{eff}^{↑↓}) of a heavy-metal-ferromagnet (HM-FM) interface characterizes the efficiency of the interfacial spin transport. Accurately determining G_{eff}^{↑↓} is critical to the quantitative understanding of measurements of direct and inverse spin Hall effects. G_{eff}^{↑↓} is typically ascertained from the inverse dependence of magnetic damping on the FM thickness under the assumption that spin pumping is the dominant mechanism affecting this dependence. We report that this assumption fails badly in many in-plane magnetized prototypical HM-FM systems in the nanometer-scale thickness regime. Instead, the majority of the damping is from two-magnon scattering at the FM interface, while spin-memory-loss scattering at the interface can also be significant. If these two effects are neglected, the results will be an unphysical "giant" apparent G_{eff}^{↑↓} and hence considerable underestimation of both the spin Hall ratio and the spin Hall conductivity in inverse or direct spin Hall experiments.