Spin Quantization in Heavy Ion Collision

We analyzed recent experimental data on the disassembly of 28Si into 7α in terms of a hybrid α-cluster model. We calculated the probability of breaking into several α-like fragments for high l-spin values for identical and non-identical spin zero nuclei. Resonant energies were found for each l-value and compared to the data and other theoretical models. Toroidal-like structures were revealed in coordinate and momentum space when averaging over many events at high l. The transition from quantum to classical mechanics is highlighted.

Quantum spin mixing in Dirac materials

The spin of the electron is nowadays replacing the charge as basic carrier of information not only in spintronics applications, but also in the emerging field of quantum information. Topological quantum materials, where spin-momentum locking is believed to lead to particularly long spin lifetimes, are regarded as a promising platform for such applications. However, spin-orbit coupling, that is essential to all topological matter, at the same time gives rise to spin mixing and decoherence as a major obstacle for quantum computing. Here, we give experimental evidence that hot-spots of spin-mixing and spin-conserving contributions of the spin-orbit operator coexist in an archetypal topological Dirac metal, and that these hot spots can have a strongly anisotropic distribution of their respective wave vectors with respect to the spin quantization direction. Our results can be understood within a theory that takes into account the decomposition of the spin-orbit Hamiltonian into spin-conserving and spin-flip terms, contributing to a better understanding of quantum decoherence in topological materials, in general.

Emergence of Nontrivial Spin Textures in Frustrated Van Der Waals Ferromagnets

In this work, first principles ground state calculations are combined with the dynamic evolution of a classical spin Hamiltonian to study the metamagnetic transitions associated with the field dependence of magnetic properties in frustrated van der Waals ferromagnets. Dynamically stabilized spin textures are obtained relative to the direction of spin quantization as stochastic solutions of the Landau–Lifshitz–Gilbert–Slonczewski equation under the flow of the spin current. By explicitly considering the spin signatures that arise from geometrical frustrations at interfaces, we may observe the emergence of a magnetic skyrmion spin texture and characterize the formation under competing internal fields. The analysis of coercivity and magnetic hysteresis reveals a dynamic switch from a soft to hard magnetic configuration when considering the spin Hall effect on the skyrmion. It is found that heavy metals in capped multilayer heterostructure stacks host field-tunable spiral skyrmions that could serve as unique channels for carrier transport. The results are discussed to show the possibility of using dynamically switchable magnetic bits to read and write data without the need for a spin transfer torque. These results offer insight to the spin transport signatures that dynamically arise from metamagnetic transitions in spintronic devices.

Spin Quantization in a Classical Model

The origins of quantum theory lie in a failure to explain certain phenomena using classical theory. But despite its adoption, quantum theory abounds with concepts described as “weird” or “spooky.” Even Feynman said that no one understands quantum theory. We revisit the Stern-Gerlach experiment that gave rise to the concept of spin and its quantization from a classical point of view. We present a simplified model of the classical electron which has two stable states which separate into two beams in the presence of an inhomogenous magnetic field.

The Nematic Character of a Hidden Ordered State revealed by Magnetic Fields.

ABSTRACTWe examine a novel phase of the underscreened Anderson lattice Model that might pertain to the ”Hidden Ordered” phase of URu2Si2. We show that the system breaks spin-rotational invariance below the critical temperature and spontaneously selects a preferred axis of spin quantization. As a result, the low temperature phase exhibits a magnetic anisotropy, where the electronic properties depend not only on the magnitude of the magnetic field but also on the orientation of the applied field relative to the axis of quantization. The results are discussed in the context of recent experimental findings on URu2Si2.

QUANTUM STATE OF A FREE SPIN-½ PARTICLE AND THE INEXTRICABLE DEPENDENCE OF SPIN AND MOMENTUM UNDER LORENTZ TRANSFORMATIONS

We revise the Dirac equation for a free particle and investigate Lorentz transformations on spinors. We study how the spin quantization axis changes under Lorentz transformations, and evince the interplay between spin and momentum in this context.