Ilaria Bergenti

Spin routes in organic semiconductors

Organic semiconductors are characterized by a very low spin-orbit interaction, which, together with their chemical flexibility and relatively low production costs, makes them an ideal materials system for spintronics applications. The first experiments on spin injection and transport occurred only a few years ago, and since then considerable progress has been made in improving performance as well as in understanding the mechanisms affecting spin-related phenomena. Nevertheless, several challenges remain in both device performance and fundamental understanding before organic semiconductors can compete with inorganic semiconductors or metals in the development of realistic spintronics applications. In this article we summarize the main experimental results and their connections with devices such as light-emitting diodes and electronic memory devices, and we outline the scientific and technological issues that make organic spintronics a young but exciting field.

Unravelling the role of the interface for spin injection into organic semiconductors

Organic semiconductors are attractive candidates for spintronics applications because of their long spin lifetimes. But few studies have investigated how to optimize the injection of spin into these materials. A new study suggests that the metal/organic interface is key.

Electrically Programmable Magnetoresistance in Multifunctional Organic-Based Spin Valve Devices

5] In this paper we show that an electrically controlled magne-toresistance can be easily achieved in organic devices by com-bining magnetic bistability (spin valve) and electrical memory effects into an interacting multifunctional implementation. Electrical resistive switching effects in organic-based devices have recently received widespread attention

The role of aluminum oxide buffer layer in organic spin-valves performance

The electronic structures of the 8-hydroxyquinoline-aluminum (Alq(3))/Al2O3/Co interfaces were studied by photoelectron spectroscopy. A strong interface dipole was observed, which leads to a reduct ...

A Single-Device Universal Logic Gate Based on a Magnetically Enhanced Memristor

Memristors are one of the most promising candidates for future information and communications technology (ICT) architectures. Two experimental proofs of concept are presented based on the intermixing of spintronic and memristive effects into a single device, a magnetically enhanced memristor (MEM). By exploiting the interaction between the memristance and the giant magnetoresistance (GMR), a universal implication (IMP) logic gate based on a single MEM device is realized.

Multi-modal sensing in spin crossover compounds

We exploited the solvatochromic spin-state switching in a spin crossover (SCO) compound based on the FeII complex and the simultaneous change of spectroscopic properties for selective multimodal sensing of methanol and ethanol. We demonstrate that sensing capabilities are due to the inclusion of methanol or ethanol molecules into the crystalline structure, which tailors simultaneously the transition temperature, colour, birefringence and vibrational modes. We exploited this capability by integrating a neutral compound, switchable at room temperature, into a micrometric TAG sensitive to the colour and birefringence. The system was characterised by optical microscopy, magnetic susceptibility, Raman spectroscopy and X-ray diffraction.

Understanding the role of tunneling barriers in organic spin valves by hard x-ray photoelectron spectroscopy

We present an ex situ, nondestructive chemical characterization of deeply buried organic-inorganic interfaces using hard x-ray photoelectron spectroscopy. Co/Alq3 and Co/AlOx/Alq3 interfaces were studied in order to determine the role of a thin (1–2 nm) AlOx interdiffusion barrier in organic spin valves. Interfacial Alq3, 15 nm below the surface, exhibits strong sensitivity to the electronic structure of the interfacial region and to the presence of the AlOx. In addition to reducing Co–Alq3 interdiffusion, we find that the barrier prevents charge donation from the Co to the interfacial Alq3, thus preventing the formation of Alq3 anions within the interface region.

Hanle effect missing in a prototypical organic spintronic device

We investigate spin precession (Hanle effect) in the prototypical organic spintronic giant magnetoresistance device La0.7Sr0.3MnO3/tris(8-hydroxyquinoline)/AlOx/Co. The Hanle effect is not observed in measurements taken by sweeping a magnetic field at different angles from the plane of the device. As possible explanations we discuss the tilting out of plane of the magnetization of the electrodes, exceptionally high mobility, or hot spots. Our results call for a greater understanding of spin injection and transport in such devices.

Electroluminescence and magnetoresistance of the organic light-emitting diode with a La0.7Sr0.3MnO3 anode

Electroluminescence (EL) with brightness up to 300 cd m2 is observed from organic light-emitting diodes fabricated on oxygen-treated La0.7 Sr0.3 Mn O 3 anodes. An external magnetic field of 150 mT ...

Electrochemical preparation of cobalt tips for scanning tunneling microscopy

Here we describe a straightforward electrochemical method for fabricating sharp cobalt tips. Such tips are particularly useful for those scanning tunneling microscopy (STM) experiments where the focus is on magnetic properties of the surface and the spin polarized (SP) tunneling current is the relevant property, such as in SPSTM and SP scanning tunneling spectroscopy.