Project

Topological Insulators; muon spin spectroscopy; Dirac materials; soft x-ray ARPES; Spintronic Devices; Interface Phynomena

Lead
Die Klasse der Dirac-Materialien enthält neue exotische Materialien wie topologische Isolatoren und Weyl Halbmetalle. Diese Materialien werden durch ein spezielles Verhalten ihrer Elektronen gekennzeichnet, das zuvor nicht beobachtet wurde. Dieses Verhalten eröffnet die Möglichkeit für ihre Anwendung in neuen technischen Geräte. Die Eigenschaften solcher Materialien können weiter durch Dotierung von magnetischen Elementen in ihrer chemischen Struktur abgestimmt werden und damit das Potenzial für praktische Anwendungen erweitern.
Lay summary
Das Ziel dieses Projektes ist es, Methoden zur Verfügung zu stellen, die unsere Fähigkeit, bei der Verwendung einer Kombination von Dirac Materialien vorantreiben, neue Nano-Geräte zu entwickeln, die die elektronischen und magnetischen Eigenschaften von Elektronen, oder die sogenannten Spintronik-Geräte nutzen. Zu diesem Zweck werden wir einzigartige experimentelle Methoden verwenden die nur am Paul Scherrer Institut (PSI) in der Schweiz zur Verfügung stehen. Diese Methoden ermöglichen ein besseres Verständnis der grundlegenden Eigenschaften dieser Materialien ermöglichen. Wir werden die Entwicklung der elektronischen und magnetischen Eigenschaften mit zunehmendem Gehalt an magnetischen Elemente untersuchen, um zu erfahren, wie wir können, um sie für unsere Anwendungen können abstimmen. Die komplementären experimentellen Techniken innerhalb der PSI Forschungsinfrastruktur mit Theorie sind daher die grösste Stärke unseres Kooperationsprojekt. Es wird die Position und die Sichtbarkeit der PSI und der Schweizer Wissenschaft im Allgemeinen in der heissen und hart umkämpften Feld der Spintronik Grundlagen und Anwendungen stärken.

Direct link to Lay Summary

Last update: 26.04.2016

Lead
The class of Dirac materials includes new exotic materials such as topological insulators and Weyl semimetals. These materials are characterized by a special behaviour of their electrons, which has not been observed before, and opens the possibility for their application in novel technological devices. The properties of such materials can be further tuned by incorporating magnetic elements in their chemical structure, and thus expanding the potential for practical applications.
Lay summary
The aim of this project is to provide methods that advance our ability in using a combination of Dirac materials, to engineer new nano-devices that utilize the electronic and magnetic properties of electrons, or the so called spintronic devices. For this purpose, we will use unique experimental methods, available only at the Paul Scherrer Institut (PSI) in Switzerland, that enable better understanding of the fundamental properties of these materials. We will investigate the evolution of the electronic and magnetic properties with increasing content of magnetic elements to learn how we can tune them for our applications. The complementary experimental techniques within the PSI research infrastructure combined with theory constitute the main strength of our collaborative project. It will strengthen the stand and visibility of PSI and Swiss science in general in the hot and highly competitive field of spintronics fundamentals and applications.

Direct link to Lay Summary

Last update: 26.04.2016

Active participation

Number	Title	Start	Funding scheme

The class of Dirac materials (DMs) including, apart from graphene, new exotic materials such as topological insulators (Bi2 Se3, Sb2 Te3, etc) and Weyl semimetals (NbAs, TaAs) are characterized by cones of linear electron dispersion in the vicinity of the Fermi level. Doping these materials with magnetic impurities opens a gap between the Rashba bands in otherwise time-inversion protected zero-momentum point. One of the hopes of solid-state physics in this field is to discover a system where the magnetic doping shifts this gap to the Fermi level. In this case the spin orientation becomes locked to the electron momentum, resembling the so-called Majorana fermions. With potential applications of such systems varying from magnetic transport to superconductivity, this anticipated discovery will immediately revolutionize the whole field of spintronics, pushing it from its present fundamental research domain to practical realization of spintronics devices.In this proposal, the main class of the investigated DM will be (magnetically) doped topological insulators (TIs) and their interfaces, where novel functionalities can be formed through interaction of the topologically protected surface states with impurities or different electronic states in the bulk. The focus will be on (but not limited to) the local magnetic and electronic properties of doped thin films and single crystals of TIs and Weyl semimetals, with the aim of gaining better understanding of their intriguing fundamental properties and the prospect of their spintronics applications.The DM systems will be explored with a complementary combination of low-energy muon spin relaxation (LE-µSR) and soft-X-ray ARPES (SX-ARPES) at PSI. The LE-µSR spectrometer is a worldwide unique facility which utilizes low energy (1-30 keV) spin polarized muons whose depth resolving capability coupled with high sensitivity to local magnetic fields provide a powerful tool to study local magnetic and electronic properties of buried heterostructures and impurities. The worldwide most advanced SX-ARPES facility at SLS enables direct access to a complementary aspect of buried interfaces, band dispersion resolved in electron momentum and elemental character. A multi-channel spin detector iMott enables so far unthinkable studies of spin-resolved electron dispersion in buried heterostructure and impurities systems of DMs.The complementary experimental techniques within the PSI research infrastructure combined with theory constitute the main strength of our collaborative project. It will strengthen the stand of PSI in the hot and highly competitive field of spintronics fundamentals and applications. Moreover, this will be a pioneering project combining these experimental methods, which we hope will attract potential new users for both involved facilities.