No abstract

For the purpose of recovering the intriguing electronic properties of freestanding graphene at a solid surface, graphene self-organized on a Au monolayer on Ni(111) is prepared and characterized by scanning tunneling microscopy. Angle-resolved photoemission reveals a gapless linear pi-band dispersion near K[over] as a fingerprint of strictly monolayer graphene and a Dirac crossing energy equal to the Fermi energy (EF) within 25 meV meaning charge neutrality. Spin resolution shows a Rashba effect on the pi states with a large (approximately 13 meV) spin-orbit splitting up to EF which is independent of k.

Voltage-controlled spin electronics is crucial for continued progress in information technology. It aims at reduced power consumption, increased integration density and enhanced functionality where non-volatile memory is combined with highspeed logical processing. Promising spintronic device concepts use the electric control of interface and surface magnetization. From the combination of magnetometry, spin-polarized photoemission spectroscopy, symmetry arguments and first-principles calculations, we show that the (0001) surface of magnetoelectric Cr 2 O 3 has a roughness-insensitive, electrically switchable magnetization. Using a ferromagnetic Pd/Co multilayer deposited on the (0001) surface of a Cr 2 O 3 single crystal, we achieve reversible, room-temperature isothermal switching of the exchange-bias field between positive and negative values by reversing the electric field while maintaining a permanent magnetic field. This effect reflects the switching of the bulk antiferromagnetic domain state and the interface magnetization coupled to it. The switchable exchange bias sets in exactly at the bulk Néel temperature.S pintronics strives to exploit the spin degree of freedom of electrons for an advanced generation of electronic devices 1,2 . In particular, voltage-controlled spin electronics is of vital importance to continue progress in information technology. The main objective of such an advanced technology is to reduce power consumption while enhancing processing speed, integration density and functionality in comparison with presentday complementary metal-oxide-semiconductor electronics [3][4][5][6] . Almost all existing and prototypical solid-state spintronic devices rely on tailored interface magnetism, enabling spin-selective transmission or scattering of electrons. Controlling magnetism at thin-film interfaces, preferably by purely electrical means, is a key challenge to better spintronics [7][8][9][10] . The absence of direct coupling between magnetization and electric field makes the electric control of collective magnetism in general, and surface and interface magnetism in particular, a scientific challenge. The significance of controlled interface magnetism started with the exchange-bias effect. Exchange bias is a coupling phenomenon at magnetic interfaces that manifests itself most prominently in the shift of the ferromagnetic hysteresis loop along the magnetic-field axis and is quantified by the magnitude µ 0 H EB of the shift 11 . The exchange-bias pinning of ferromagnetic thin films is employed in giant magnetoresistance and tunnelling magnetoresistance structures of magnetic-field sensors and modern magnetic read heads 12 . Electric control of exchange bias has been proposed for various spintronic applications that go beyond giant magnetoresistance and tunnelling magnetoresistance technology 5 . One approach to such voltage control requires a reversible, laterally uniform, isothermal electric tuning of the exchange-bias field at room temperature, which remains a significant challenge.Early attemp...

The software package jMRUI with Java-based graphical user interface enables user-friendly time-domain analysis of magnetic resonance spectroscopy (MRS) and spectroscopic imaging (MRSI) and HRMAS-NMR signals. Version 3.x has been distributed in more than 1200 groups or hospitals worldwide. The new version 4.x is a plug-in platform enabling the users to add their own algorithms. Moreover, it offers new functionalities compared to versions 3.x. The quantum-mechanical simulator based on NMR-SCOPE, the quantitation algorithm QUEST and the main MRSI functionalities are described. Quantitation results of signals obtained in vivo from a mouse and a human brain are given.

The kagome lattice based on 3d transition metals is a versatile platform for novel topological phases hosting symmetry-protected electronic excitations and exotic magnetic ground states. However, the paradigmatic states of the idealized two-dimensional (2D) kagome lattice -Dirac fermions and topological flat bands -have not been simultaneously observed, partly owing to the complex stacking structure of the kagome compounds studied to date. Here, we take the approach of examining FeSn, an antiferromagnetic single-layer kagome metal with spatially-decoupled kagome planes. Using polarization-and termination-dependent angleresolved photoemission spectroscopy (ARPES), we detect the momentum-space signatures of coexisting flat bands and Dirac fermions in the vicinity of the Fermi energy. Intriguingly, when complemented with bulk-sensitive de Haas-van Alphen (dHvA) measurements, our data reveal an even richer electronic structure that exhibits robust surface Dirac fermions on specific crystalline terminations. Through band structure calculations and matrix element simulations, we demonstrate that the bulk Dirac bands arise from in-plane localized Fe-3d orbitals under kagome symmetry, while the surface state realizes a rare example of fully spin-polarized 2D Dirac fermions when combined with spin-layer locking in FeSn. These results highlight FeSn as a prototypical host for the emergent excitations of the kagome lattice. The prospect to harness these excitations for novel topological phases and spintronic devices is a frontier of great promise at the confluence of topology, magnetism, and strongly-correlated electron physics.