premio tesi di dottorato – 50 – PREMIO TESI DI DOTTORATO Commissione giudicatrice, anno 2014 Luigi Lotti, presidente della Commissione Tito Arecchi, Area scientifica Aldo Bompani, Area Scienze Sociali Franco Cambi, Area Umanistica Paolo Felli, Area Tecnologica Michele Arcangelo Feo, Area Umanistica Roberto Genesio, Area Tecnologica Mario Pio Marzocchi, Area Scientifica Adolfo Pazzagli, Area Biomedica Giuliano Pinto, Area Umanistica Salvatore Ruggieri, Area Biomedica Saulo Sirigatti, Area Biomedica Fiorenzo Cesare Ugolini, Area Tecnologica Vincenzo Varano, Area Scienze Sociali Graziella Vescovini, Area Umanistica Luigi Malavolti Single molecule magnets sublimated on conducting and magnetic substrates Firenze University Press 2015 Single molecule magnets sublimated on conducting and magnetic substrates / Luigi Malavolti. – Firenze : Firenze University Press, 2015. (Premio Tesi di Dottorato; 50) http://digital.casalini.it/9788866559702 ISBN 978-88-6655-969-6 (print) ISBN 978-88-6655-970-2 (online) Peer Review Process All publications are submitted to an external refereeing process under the responsibility of the FUP Editorial Board and the Scientific Committees of the individual series. The works published in the FUP catalogue are evaluated and approved by the Editorial Board of the publishing house. For a more detailed description of the refereeing process we refer to the official documents published on the website and in the online catalogue of the FUP (www.fupress.com). Firenze University Press Editorial Board G. Nigro (Co-ordinator), M.T. Bartoli, M. Boddi, R. Casalbuoni, C. Ciappei, R. Del Punta, A. Dolfi, V. Fargion, S. Ferrone, M. Garzaniti, P. Guarnieri, A. Mariani, M. Marini, A. Novelli, M.C. Torricelli, M. Verga, A. Zorzi. This work is licensed under a Creative Commons Attribution 4.0 International (CC BY 4.0: http://creativecommons.org/licenses/by/4.0/) CC 2015 Firenze University Press Università degli Studi di Firenze Firenze University Press Borgo Albizi, 28, 50122 Firenze, Italy www.fupress.com Printed in Italy A Donatella, alla mia famiglia “Beyond the horizon of the place we lived when we were young In a world of magnets and miracles Our thoughts strayed constantly and without boundary The ringing of the division bell had begun ...” “High Hopes”, Pink Floyd Index Section 1 Introduction 9 Section 2 Experimental methods 13 l Bulk magnetic characterisation 1.1 Standard magnetometry 14 1.2 Ac susceptometry 15 2 Sublimation process 17 3 Quartz Crystal Microbalance 18 4 PhotoElectron Spectroscopy (PES) 19 4.1 X-ray Photoemission Spectroscopy (XPS) 22 4.2 Ultraviolet Photoemission Spectroscopy (UPS) 25 5 X-ray Absorption Spectroscopy (XAS) 25 5.1 X-ray synchrotron radiation 26 5.2 X-ray absorption spectroscopy principles 27 5.3 X-ray Magnetic Circular Dichroism (XMCD) 28 5.4 X-ray Natural Linear Dichroism (XNLD) 31 5.5 X-ray absorption detection 31 6 DEIMOS beamline 32 7 Low Energy Ion Scattering (LEIS) 33 8 Scanning Probe Microscopies (SPM) 34 8.1 Scanning Tunnelling Microscopy (STM) 34 8.2 Tunnelling effect 35 8.3 Scanning Tunnelling Spectroscopy (STS) 39 9 Multiplatform Ultra-High Vacuum system 39 9.1 Sublimation chamber 40 9.2 XPS, UPS and LEIS chamber 40 9.3 STM Omicron system 41 Section 3 The terbium bis(phthalocyaninato) complex 43 l Introduction 43 2 Erratic magnetic hysteresis 46 Luigi Malavolti, Single molecule magnets sublimated on conducting and magnetic substrates , ISBN 978-88-6655-969-6 (print) ISBN 978-88-6655-970-2 (online) CC BY 4.0, 2015 Firenze University Press 2.1 TbPC 2 synthesis 46 2.2 Microcrystalline [TbPC 2 l0 ·CH 2 Ch 2 hysteresis 47 2.4 TbPC 2 in magnetic dilution environment 52 2.5 Evaluation of the exchange interaction 54 2.6 Magnetic Circular Dichroism ofTbPC 2 sublimated on quartz 56 3 Characterisation of thick films through low-energy implanted muons 58 4 Toward TbPC2 spintronic devices 67 4.1 Introduction 67 4.2 TbPC 2 /LSMO/STO hybrid surface 68 4.3 TbPC 2 /CO/CU(lOO) hybrid surface 72 Section 4 The Fe 4 SMM class 83 l Introduction 83 2 Thick film characterisation 86 3 Preparation and XPS characterisation of Fe4Ph deposited on Au(111) at lowcoverage 89 4 STM characterisation of Fe 4 Ph sub-monolayer on Au(111) 91 4.1 Back exposure sublimation test 94 5 STM investigation on Cu(100) surface 95 6 STM investigation on CU 2 N/CU(100) surface 97 7 STS and IETS measurements 98 Section 5 Conclusion 105 References 107 Acknowledgments 115 Single molecule magnets sublimated on conducting and magnetic substrates 8 Luigi Malavolti, Single molecule magnets sublimated on conducting and magnetic substrates , ISBN 978-88-6655-969-6 (print) ISBN 978-88-6655-970-2 (online) CC BY 4.0, 2015 Firenze University Press Single molecule magnets sublimated on conducting and magnetic substrates 10 Luigi Malavolti 11 Single molecule magnets sublimated on conducting and magnetic substrates 12 𝜒𝜒 𝜒𝜒 𝜒 𝛿𝛿𝛿𝛿 𝛿𝛿𝛿𝛿 ሺͳሻ 𝑀𝑀 𝐻𝐻 𝛿𝛿𝛿𝛿 𝑚𝑚 𝑚𝑚 𝜒 𝑚 𝛿𝛿𝛿𝛿 𝛿𝛿𝛿𝛿 ሺʹሻ 𝛿𝛿 𝑛𝑛 𝑛𝑛 𝑀𝑀 𝜒 𝑁𝑁 ∑ (−𝛿𝛿𝛿𝛿 𝑛𝑛 /𝛿𝛿𝛿𝛿) 𝑛𝑛 𝑒𝑒𝑒𝑒𝑒𝑒(−𝛿𝛿 𝑛𝑛 /𝑘𝑘𝑘𝑘) ∑ 𝑒𝑒𝑒𝑒𝑒𝑒(−𝛿𝛿 𝑛𝑛 /𝑘𝑘𝑘𝑘) 𝑛𝑛 ሺ͵ሻ 𝑇𝑇 𝑘𝑘 Luigi Malavolti, Single molecule magnets sublimated on conducting and magnetic substrates , ISBN 978-88-6655-969-6 (print) ISBN 978-88-6655-970-2 (online) CC BY 4.0, 2015 Firenze University Press − 𝛿𝛿𝛿𝛿 𝛿𝛿𝛿𝛿 ⁄ 𝛿𝛿 Single molecule magnets sublimated on conducting and magnetic substrates 14 𝜒𝜒 𝜒𝜒 𝜒 𝑀𝑀 𝑁𝑁 · 𝐻𝐻 ሺͶሻ 𝑀𝑀 𝑁𝑁 𝐵𝐵 0 Luigi Malavolti 15 𝐵𝐵 𝐵 𝐵𝐵 0 + ℎ cos 𝜔𝜔𝜔𝜔 ሺͷሻ ℎ 𝜔𝜔 𝐵𝐵 0 𝑀𝑀𝑀𝜔𝜔𝑀 𝐵 𝑀𝑀 0 + 𝜒𝜒𝑀𝜔𝜔𝑀ℎ ሺሻ 𝜒𝜒 ′ 𝜒𝜒 ′′ 𝜒𝜒𝑀𝜔𝜔𝑀 𝜒𝜒𝑀𝜔𝜔𝑀 𝐵 𝜒𝜒 ′ cos 𝜔𝜔𝜔𝜔 + 𝜒𝜒 ′′ sin 𝜔𝜔𝜔𝜔 ሺሻ 𝑀𝑀𝑀𝜔𝜔𝑀 𝐵 𝑀𝑀 0 + 𝑀𝜒𝜒 ′ cos 𝜔𝜔𝜔𝜔 + 𝜒𝜒 ′′ sin 𝜔𝜔𝜔𝜔𝑀ℎ ሺ ͅሻ 𝜏𝜏 𝜏𝜏 −1 𝜔𝜔𝜏𝜏 ≪ 1 𝜒𝜒 𝑇𝑇 𝜏𝜏 −1 𝜔𝜔𝜏𝜏 ≫ 1 𝜒𝜒 𝑆𝑆 𝜏𝜏 −1 𝜒𝜒 ′ 𝐵 𝜒𝜒 𝑇𝑇 −𝜒𝜒 𝑆𝑆 1+𝜔𝜔 2 𝜏𝜏 2 + 𝜒𝜒 𝑆𝑆 ( 9 ) 𝜒𝜒 ′′ 𝐵 𝑀𝜒𝜒 𝑇𝑇 −𝜒𝜒 𝑆𝑆 𝑀𝜔𝜔𝜏𝜏 1+𝜔𝜔 2 𝜏𝜏 2 ሺͳͲሻ Single molecule magnets sublimated on conducting and magnetic substrates 16 𝜒𝜒 ′ (𝜔𝜔) = 𝜒𝜒 𝑆𝑆 + (𝜒𝜒 𝑇𝑇 − 𝜒𝜒 𝑆𝑆 ) 1+(𝜔𝜔𝜔𝜔) 1−𝛼𝛼 sin(𝜋𝜋𝜋𝜋 𝜋 ⁄ ) 1+𝜋(𝜔𝜔𝜔𝜔) 1−𝛼𝛼 sin(𝜋𝜋𝜋𝜋 𝜋 ⁄ )+ (𝜔𝜔𝜔𝜔) 2−2𝛼𝛼 ሺͳͳሻ 𝜒𝜒 ′′ (𝜔𝜔) = (𝜒𝜒 𝑇𝑇 − 𝜒𝜒 𝑆𝑆 ) 1+(𝜔𝜔𝜔𝜔) 1−𝛼𝛼 cos(𝜋𝜋𝜋𝜋 𝜋 ⁄ ) 1+𝜋(𝜔𝜔𝜔𝜔) 1−𝛼𝛼 sin(𝜋𝜋𝜋𝜋 𝜋 ⁄ )+ (𝜔𝜔𝜔𝜔) 2−2𝛼𝛼 ሺͳʹሻ 𝛼𝛼 𝛼𝛼 ͳʹ 𝜏𝜏 𝛼𝛼 𝜏𝜏 𝛼𝛼 Luigi Malavolti 17 𝛥𝛥𝛥𝛥 = 𝐾𝐾 𝜌𝜌𝜌𝜌𝜌𝜌𝜌𝜌𝑐𝑐 tan −1 {𝑧𝑧 tan[ 𝜋𝜋𝜋𝜌𝜌𝑞𝑞−𝜌𝜌𝑐𝑐) 𝜌𝜌𝑞𝑞 ]} ሺͳ͵ሻ 𝛥𝛥𝛥𝛥 𝜌𝜌 𝑓𝑓 𝑐𝑐 𝑓𝑓 𝑞𝑞 𝐾𝐾 𝑧𝑧 Single molecule magnets sublimated on conducting and magnetic substrates 18 ℎ𝜐𝜐 𝐸𝐸 𝐾𝐾𝐾𝐾𝐾𝐾 𝐸𝐸 𝐵𝐵 𝐸𝐸 𝐵𝐵 = ℎ𝜐𝜐 𝜐 𝐸𝐸 𝐾𝐾𝐾𝐾𝐾𝐾 + 𝜙𝜙 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝜐 𝜙𝜙 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 ሺͳͶሻ 𝜙𝜙 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝜙𝜙 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝜙𝜙 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝜐 𝜙𝜙 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 Luigi Malavolti 19 𝐸𝐸 𝐾𝐾𝐾𝐾𝐾𝐾 ′ 𝐸𝐸 𝐾𝐾𝐾𝐾𝐾𝐾 𝐸𝐸 𝐾𝐾𝐾𝐾𝐾𝐾 ′ = 𝐸𝐸 𝐾𝐾𝐾𝐾𝐾𝐾 − ∆𝐸𝐸 ሺͳͷሻ Single molecule magnets sublimated on conducting and magnetic substrates 20