Université de Fribourg

Temporal mapping of photochemical reactions and molecular excited states with carbon specificity

Wang, K. ; Murahari, P. ; Yokoyama, K. ; Lord, J. S. ; Pratt, F. L. ; He, J. ; Schulz, Leander ; Willis, M. ; Anthony, J. E. ; Morley, N. A. ; Nuccio, Laura ; Misquitta, A. ; Dunstan, D. J. ; Shimomura, K. ; Watanabe, I. ; Zhang, S. ; Heathcote, P. ; Drew, Alan J.

In: Nature Materials, 2017, vol. 16, no. 4, p. 467–473

Photochemical reactions are essential to a large number of important industrial and biological processes. A method for monitoring photochemical reaction kinetics and the dynamics of molecular excitations with spatial resolution within the active molecule would allow a rigorous exploration of the pathway and mechanism of photophysical and photochemical processes. Here we demonstrate that...

Université de Fribourg

Future directions of μSR—laser excitation

Yokoyama, K. ; Murahari, P. ; Heathcote, P. ; Nuccio, Laura ; Lord, J. S. ; Morley, N. A. ; Drew, Alan J.

In: Physica Scripta, 2014, vol. 88, no. 6, p. 068511

We discuss the general principles of laser-excited muon pump–probe spin spectroscopy (photo-μSR), including the historical origins of the technique, and discuss the overall experimental method. We review examples of past work using this technique, then discuss the future upgrade of the HiFi spectrometer with a high-power laser system. In particular, we note that performing photo-μSR...

Université de Fribourg

Engineering spin propagation across a hybrid organic/inorganic interface using a polar layer

Schulz, Leander ; Nuccio, L. ; Willis, M. ; Desai, P. ; Shakya, P. ; Kreouzis, T. ; Malik, Vivek Kumar ; Bernhard, Christian ; Pratt, F. L. ; Morley, N. A. ; Suter, A. ; Nieuwenhuys, G. J. ; Prokscha, T. ; Morenzoni, E. ; Gillin, W. P. ; Drew, Alan J.

In: Nature Materials, 2011, vol. 10, p. 39–44

Spintronics has shown a remarkable and rapid development, for example from the initial discovery of giant magnetoresistance in spin valves (Baibich, M. N. et al. Giant magnetoresistance of (001)Fe/(001)Cr magnetic superlattices. Phys. Rev. Lett. 61, 2472–2475, 1988) to their ubiquity in hard-disk read heads in a relatively short time. However, the ability to fully harness electron spin as...

Université de Fribourg

Direct measurement of the electronic spin diffusion length in a fully functional organic spin valve by low-energy muon spin rotation

Drew, Alan J. ; Hoppler, Julian ; Schulz, Leander ; Pratt, F. L. ; Desai, P. ; Shakya, P. ; Kreouzis, T. ; Gillin, W. P. ; Suter, A. ; Morley, N. A. ; Malik, Vivek Kumar ; Dubroka, Adam ; Kim, Kyung Wan ; Bouyanfif, Houssny ; Bourqui, Francis ; Bernhard, Christian ; Scheuermann, R. ; Nieuwenhuys, G. J. ; Prokscha, T. ; Morenzoni, E.

In: Nature Materials, 2009, vol. 8, p. 109 - 114

Electronic devices that use the spin degree of freedom hold unique prospects for future technology. The performance of these 'spintronic' devices relies heavily on the efficient transfer of spin polarization across different layers and interfaces. This complex transfer process depends on individual material properties and also, most importantly, on the structural and electronic properties of the...

Université de Fribourg

Intrinsic Mobility Limit for Anisotropic Electron Transport in Alq₃

Drew, Alan J. ; Pratt, F. L. ; Hoppler, Justin ; Schulz, Leander ; Malik, Vivek Kumar ; Morley, N. A. ; Desai, P. ; Shakya, P. ; Kreouzis, T. ; Gillin, W. P. ; Kim, Kyung Wan ; Dubroka, Adam ; Scheuermann, R.

In: Physical Review Letters, 2008, vol. 100, p. 116601

Muon spin relaxation has been used to probe the charge carrier motion in the molecular conductor Alq₃ (tris[8-hydroxy-quinoline] aluminum). At 290 K, the magnetic field dependence of the muon spin relaxation corresponds to that expected for highly anisotropic intermolecular electron hopping. Intermolecular mobility in the fast hopping direction has been found to be 0.23±0.03 cm² V⁻¹ s⁻¹...