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Research

Spintronics of functional materials

The focus is on studying emergent phenomena in Spintronics. More specifically, we study emergent functionalities that arise due to the manipulation of different electronic orders in diverse functional materials as exotic semicoductors, correlated oxides, topological insulators, graphene etc. We look into new approaches that utilize electric, magnetic and current control of magnetization in novel devices by combining one or more of these functional materials. Novel transport properties that arise due to correlation effects between the charge orbital and spin hold potential for future electronic devices.

Broadly, the three research directions are:

Spin transport in all-Oxide heterojunctions: We have demonstrated hot-electron transport in a strongly correlated material as LaSrMnO3. We have determined the energy dependence of the hot electron attenuation length and studied the role of strong correlation to transport in such materials. We studied this using the technique of Ballistic Electron Emission Microscope and have now expanded our research focus to studying spin transport in LSMO in oxide spin valves. We also have an active research line related to the study of hot electron transport in other correlated oxides as SrRuO­3 and BiFeO3 and are active in the study of novel (spin) transport phenomena at other heterointerfaces.

Fig. 1: (Left) Hot electron transport scheme in a LSMO/Nb:STO oxide heterointerface ; (Right) Electron transport in a vertical geometry in a Graphene/n-Si device
Fig. 1: (Left) Hot electron transport scheme in a LSMO/Nb:STO oxide heterointerface ; (Right) Electron transport in a vertical geometry in a Graphene/n-Si device

Hot electron transport across a Graphene/Silicon Schottky interface: We study vertical transport in a Graphene/Silicon Schottky interface using a new device architecture. Such studies go beyond the demonstrated lateral charge and spin transport in graphene and reveal new transport characteristics intrinsic to graphene and sheds light on the influence of extrinsic parameters to vertical transport in graphene. The current focus is on studying vertical transport in graphene using hot electrons at higher energies where transport can be markedly different from that close to the Dirac point. Additionally, we also look into transport in graphene/Silicon interfaces at the nanoscale using the unique technique of Ballistic Electron Emission Microscopy.

Spin dynamics and spin transport in topological insulator materials: Recently, a new class of material has gained attention in condensed matter: topological insulators (TIs). These materials are electrically insulating in the bulk but have a single Dirac cone linear dispersion at the surface. These surface states are topologically protected meaning that these are robust against non-magnetic impurity scattering and localization effects leading to non-dissipative transport. Due to time-reversal symmetry, the spin orientation of the charge carriers is locked to their momentum which makes this class of materials appealing for spintronic applications. Here, spins can be manipulated without the use of ferromagnetic contacts. We investigate spin transport and spin dynamics in thin films of Bi¬2Se3 and Bi2Te3 using different device schemes and seek to address the efficiency of spin injection and study spin relaxation mechanisms in these materials. Samples are obtained from national and international collaborations.

(left) Surface state dispersion inside bulk band gap of a topological insulator. (right) Spin-momentum locking of the surface states (spin orientation as indicated by red arrows)
(left) Surface state dispersion inside bulk band gap of a topological insulator. (right) Spin-momentum locking of the surface states (spin orientation as indicated by red arrows)

Bachelor/Master projects: There are a couple of exciting projects available in this topic. Please contact one of the people involved in case you are interested.

People involved in this project:

Sander Kamerbeek - PhD student

Saurabh Roy - PhD student

Roald Ruiter - PhD student

Eric de Vries - PhD student

Ewout Mallon - Master student

Tamalika Banerjee - Associate Professor

Former master and PhD students:

Subir Parui, Guarav Rana, Jan van der Ploeg, Hiwa Modarresi, Vsevolod Khikhlovskyi, Pieter Klandermans, Alim Solmaz, Bart Wit, Eline Begemann

Laatst gewijzigd:09 juli 2015 10:59