Interfacial Coexistence of Superconductivity and Magnetism in NbN/Ti/MnBi2Te4 Heterostructures.
Abstract:
Magnetic/superconducting heterostructures represent a frontier in condensed matter physics, offering pathways to realize unconventional pairing mechanisms such as topological superconductivity, spin-triplet pairing, and Majorana zero modes for fault-tolerant quantum computing. In this work, we integrate the magnetic van der Waals material MnBi2Te4 (MBT) with a superconducting NbN thin film, achieving ultralow-disorder interfaces through Ti buffer layer engineering. Temperature- and field-dependent critical currents, extracted from differential resistance spectra, reveal robust coupling between the MnBi2Te4 and the superconducting order of NbN, enabling proximity-induced superconductivity within MnBi2Te4. Notably, the proximity-induced critical currents remain invariant under in-plane field rotation, in contrast to the anisotropic response observed in pristine NbN. Moreover, the hysteretic behavior observed in the interfacial magnetoresistance curves confirms the proximity-induced spin polarization at the MBT interface, which is consistent with Andreev reflection results. These findings demonstrate a platform for fabricating high-quality heterointerfaces and enable targeted exploration of exotic quantum states.Manipulation of skyrmion motion by magnetic field gradients
Abstract:
Full size CCD camera videos for https://www.nature.com/articles/s41467-018-04563-4Mode locking between helimagnetism and ferromagnetism
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.
Mapping the temperature dependent surface states of Bi2Te3 topological insulator flakes by ultra-cryogenic terahertz near-field nanoscopy
Abstract:
Topological insulators (TIs) have drawn considerable attention for next generation high sensitivity, high efficiency devices thanks to their unique metallic surface conductivity via their topologically-protected surface states (TSSs). In this study, we utilized near-field nanoimaging and nanoscale spectroscopy in the Terahertz (THz) frequency range to explore the optical response of the surface layer from Bi2Te3 TI flakes. In all cases, we observe a higher near-field optical response from the TI flakes compared to a Si substrate. This contrast increases for more surface sensitive probing, which indicates the presence of a conductive surface state. In addition, we have performed temperature dependent THz nanoscopy and demonstrate a significantly enhanced near-field contrast for the TI flake at a sample temperature of 8.9 K compared to the Si substrate. This temperature-dependent behavior provides vital insight into the underlying mechanisms behind the observed conductive surface state in TI materials.