Lapo Bogani
Professor of Molecular Nanomaterials
Telephone: +44 1865 283341
The magnetic and electronic properties of materials at the nanoscale. We pay particular attention to molecular systems, and how they can lead to multifunctional quantum materials and to nanoscale electronic devices. My group is:
- Investigating the interplay betweeen spins and flowing electrons in molecular systems
- Synthetizing magnetic materials with novel quantum properties
- Developing ultra-sensitive instrumentation for the investigation of single molecules
New Postgraduate Research Projects Available
Selected Publications
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Combining Molecular Spintronics with Electron Paramagnetic Resonance: The Path Towards Single-Molecule Pulsed Spin Spectroscopy
Slota, M, Bogani, LNovember 2020|Journal article|Applied Magnetic Resonance<jats:title>Abstract</jats:title><jats:p>We provide a perspective on how single-molecule magnets can offer a platform to combine quantum transport and paramagnetic spectroscopy, so as to deliver time-resolved electron paramagnetic resonance at the single-molecule level. To this aim, we first review the main principles and recent developments of molecular spintronics, together with the possibilities and limitations offered by current approaches, where interactions between leads and single-molecule magnets are important. We then review progress on the electron quantum coherence on devices based on molecular magnets, and the pulse sequences and techniques necessary for their characterization, which might find implementation at the single-molecule level. Finally, we highlight how some of the concepts can also be implemented by including all elements into a single molecule and we propose an analogy between donor–acceptor triads, where a spin center is sandwiched between a donor and an acceptor, and quantum transport systems. We eventually discuss the possibility of probing spin coherence during or immediately after the passage of an electron transfer, based on examples of transient electron paramagnetic resonance spectroscopy on molecular materials.</jats:p> -
Dynamical nuclear decoupling of electron spins in molecular graphenoid radicals and biradicals
LOMBARDI, F, MYERS, W, Ma, J, Liu, J, Feng, X, BOGANI, LMarch 2020|Journal article|Physical Review B -
Quantum units from the topological engineering of molecular graphenoids.
Lombardi, F, Lodi, A, Ma, J, Liu, J, Slota, M, Narita, A, Myers, WK, Müllen, K, Feng, X, Bogani, LNovember 2019|Journal article|Science (New York, N.Y.)Robustly coherent spin centers that can be integrated into devices are a key ingredient of quantum technologies. Vacancies in semiconductors are excellent candidates, and theory predicts that defects in conjugated carbon materials should also display long coherence times. However, the quantum performance of carbon nanostructures has remained stunted by an inability to alter the sp2-carbon lattice with atomic precision. Here, we demonstrate that topological tailoring leads to superior quantum performance in molecular graphene nanostructures. We unravel the decoherence mechanisms, quantify nuclear and environmental effects, and observe spin-coherence times that outclass most nanomaterials. These results validate long-standing assumptions on the coherent behavior of topological defects in graphene and open up the possibility of introducing controlled quantum-coherent centers in the upcoming generation of carbon-based optoelectronic, electronic, and bioactive systems. -
Efficient heating of single-molecule junctions for thermoelectric studies at cryogenic temperatures
Gehring, P, van der Star, M, Evangeli, C, Le Roy, JJ, Bogani, L, Kolosov, OV, van der Zant, HSJAugust 2019|Journal article|APPLIED PHYSICS LETTERS -
Accurate and unequivocal determination of the crystal-field parameters of lanthanide ions via a multitechnique approach
Slota, M, Jiang, S-D, Heintze, E, Rechkemmer, Y, Dressel, M, van Slageren, J, Bogani, LApril 2019|Journal article|PHYSICAL REVIEW B -
Tailored homo- and hetero- lanthanide porphyrin dimers: a synthetic strategy for integrating multiple spintronic functionalities into a single molecule.
Le Roy, JJ, Cremers, J, Thomlinson, IA, Slota, M, Myers, WK, Horton, PH, Coles, SJ, Anderson, HL, Bogani, LDecember 2018|Journal article|Chemical scienceWe present the design, synthesis and magnetic properties of molecular magnetic systems that contain all elements necessary for spin-valve control in molecular spintronic devices in a single molecule. We investigate the static and dynamic magnetic properties and quantum spin properties of butadiyne-linked homo- and hetero-nuclear lanthanide-porphyrin dimers. A heterometallated porphyrin dimer containing both TbIII and DyIII centres is created rationally by the stepwise oxidative homocoupling of distinct lanthanide-porphyrin monomers. TbIII and DyIII mononuclear porphyrin complexes, homodimers and heterodimers all exhibit slow magnetic relaxation below 10 kelvin under a static magnetic field. The coherence times for GdIII porphyrin monomers and dimers are found to be in excess of 3.0 μs at 2 K, allowing distinct magnetic manipulations in low temperature transport experiments. -
Publisher Correction: Magnetic edge states and coherent manipulation of graphene nanoribbons.
Slota, M, Keerthi, A, Myers, WK, Tretyakov, E, Baumgarten, M, Ardavan, A, Sadeghi, H, Lambert, CJ, Narita, A, Müllen, K, Bogani, LSeptember 2018|Journal article|NatureIn Fig. 1 of this Letter, there should have been two nitrogen (N) atoms at the 1,3-positions of all the blue chemical structures (next to the oxygen atoms), rather than one at the 2-position. The figure has been corrected online, and the original incorrect figure is shown as Supplementary Information to the accompanying Amendment. -
Magnetic edge states and coherent manipulation of graphene nanoribbons.
Slota, M, Keerthi, A, Myers, WK, Tretyakov, E, Baumgarten, M, Ardavan, A, Sadeghi, H, Lambert, CJ, Narita, A, Müllen, K, Bogani, LMay 2018|Journal article|NatureGraphene, a single-layer network of carbon atoms, has outstanding electrical and mechanical properties 1 . Graphene ribbons with nanometre-scale widths2,3 (nanoribbons) should exhibit half-metallicity 4 and quantum confinement. Magnetic edges in graphene nanoribbons5,6 have been studied extensively from a theoretical standpoint because their coherent manipulation would be a milestone for spintronic 7 and quantum computing devices 8 . However, experimental investigations have been hampered because nanoribbon edges cannot be produced with atomic precision and the graphene terminations that have been proposed are chemically unstable 9 . Here we address both of these problems, by using molecular graphene nanoribbons functionalized with stable spin-bearing radical groups. We observe the predicted delocalized magnetic edge states and test theoretical models of the spin dynamics and spin-environment interactions. Comparison with a non-graphitized reference material enables us to clearly identify the characteristic behaviour of the radical-functionalized graphene nanoribbons. We quantify the parameters of spin-orbit coupling, define the interaction patterns and determine the spin decoherence channels. Even without any optimization, the spin coherence time is in the range of microseconds at room temperature, and we perform quantum inversion operations between edge and radical spins. Our approach provides a way of testing the theory of magnetism in graphene nanoribbons experimentally. The coherence times that we observe open up encouraging prospects for the use of magnetic nanoribbons in quantum spintronic devices. -
Strong Coupling of Microwave Photons to Antiferromagnetic Fluctuations in an Organic Magnet.
,Mergenthaler, M, Liu, J, Le Roy, JJ, Ares, N, Thompson, AL, Bogani, L, Luis, F, Blundell, SJ, Lancaster, T, Ardavan, A, Briggs, GAD, Leek, PJet alOctober 2017|Journal article|Physical review lettersCoupling between a crystal of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium radicals and a superconducting microwave resonator is investigated in a circuit quantum electrodynamics (circuit QED) architecture. The crystal exhibits paramagnetic behavior above 4 K, with antiferromagnetic correlations appearing below this temperature, and we demonstrate strong coupling at base temperature. The magnetic resonance acquires a field angle dependence as the crystal is cooled down, indicating anisotropy of the exchange interactions. These results show that multispin modes in organic crystals are suitable for circuit QED, offering a platform for their coherent manipulation. They also utilize the circuit QED architecture as a way to probe spin correlations at low temperature. -
Membrane-based torque magnetometer: Enhanced sensitivity by optical readout of the membrane displacement.
Blankenhorn, M, Heintze, E, Slota, M, van Slageren, J, Moores, BA, Degen, CL, Bogani, L, Dressel, MSeptember 2017|Journal article|The Review of scientific instrumentsThe design and realization of a torque magnetometer is reported that reads the deflection of a membrane by optical interferometry. The compact instrument allows for low-temperature measurements of tiny crystals less than a microgram with a significant improvement in sensitivity, signal-to-noise ratio as well as data acquisition time compared with conventional magnetometry and offers an enormous potential for further improvements and future applications in different fields. Magnetic measurements on single-molecule magnets demonstrate the applicability of the membrane-based torque magnetometer.