Professor Thorsten Hesjedal FInstP

Abstract:

Full size CCD camera videos for https://www.nature.com/articles/s41467-018-04563-4

Abstract:

Non-collinear spin textures, such as spin spirals and skyrmions, exhibit rich emergent physics in their spin dynamics. Nevertheless, the potential to utilize their distinctive spin resonance characteristics for on-chip microwave magnonic applications is rarely explored. Here we demonstrate microwave emission and mode coupling from the resonating spin spiral lattice in a Cu₂OSeO₃/Pt/NiFe heterostructure. We use time-resolved resonant elastic X-ray scattering to visualize the exact vectorial spin precession modes from the two magnetic species in real time. Our results show that the ferromagnetic NiFe layer dynamically captures the excitation modes of the conical order in helimagnet Cu₂OSeO₃. The off-resonance NiFe spin precession is phase locked to the helimagnet with a fixed offset, thereby presenting distinct chiral dynamics. This demonstrates that the magnons produced in the process—referred to as helimagnons—can wirelessly transmit spin information at gigahertz frequencies, opening new avenues for on-chip microwave magnonics.

Abstract:

<jats:p>In this perspective article, we explore some of the promising spin and topology material platforms (e.g., spins in semiconductors and superconductors, skyrmionic, topological, and two-dimensional materials) being developed for such quantum components as qubits, superconducting memories, sensing, and metrological standards, and discuss their figures of merit. Spin- and topology-related quantum phenomena have several advantages, including high coherence time, topological protection and stability, low error rate, relative ease of engineering and control, and simple initiation and readout. However, the relevant technologies are at different stages of research and development, and here, we discuss their state-of-the-art, potential applications, challenges, and solutions.</jats:p>

Abstract:

Disordered two-dimensional (2D) lattices, including hexatic and various glassy states, are observed in a wide range of 2D systems including colloidal nanoparticle assemblies and fluxon lattices. Their disordered nature determines the stability and mobility of these systems, as well as their response to the external stimuli. Here we report on the controlled creation and characterization of a disordered 2D lattice of nontopological magnetic bubbles in the noncentrosymmetric ferrimagnetic alloy Mn1.4PtSn. By analyzing the type and frequency of fundamental lattice defects, such as dislocations, the orientational correlation, as well as the induced motion of the lattice in an external field, a nonergodic glassy state, stabilized by directional application of an external field, is revealed.