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Heterogeneous Optically-Detected Spin-Acoustic Resonance in Solid-State Molecular Thin-film
Authors:
Kuan-Cheng Chen,
Yongqiang Wen,
Xiaotian Xu,
Max Attwood,
Jingdong Xu,
Chen Fu,
Sami Ramadan,
Shang Yu,
Sandrine Heutz,
Mark Oxborrow
Abstract:
We report an implementation of spin-acoustic resonance in pentacene thin films integrated on a high-quality-factor (high-Q) surface acoustic wave (SAW) resonator on a lithium niobate substrate. Heterogeneous optically detected spin-acoustic resonance (HODSAR) is an optically detected spin-resonance measurement in which the resonant drive is delivered mechanically by a surface acoustic wave (SAW).…
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We report an implementation of spin-acoustic resonance in pentacene thin films integrated on a high-quality-factor (high-Q) surface acoustic wave (SAW) resonator on a lithium niobate substrate. Heterogeneous optically detected spin-acoustic resonance (HODSAR) is an optically detected spin-resonance measurement in which the resonant drive is delivered mechanically by a surface acoustic wave (SAW). By leveraging the photo-excited triplet state of pentacene at room temperature, we demonstrate coherent spin manipulation via acoustic driving under zero externally applied magnetic field. The heterogeneously integrated device, referred to as HODSAR, utilizes spin-phonon coupling to achieve mechanically driven, zero-field spin resonance, opening avenues for room-temperature mechanically addressable spin control and device integration. We show that the high-Q multimode response of the SAW resonator enables spectrally selective acoustic addressing of triplet transitions near 105 MHz. Coherent control is evidenced by Rabi oscillations, with a Rabi frequency that increases linearly with the square root of the applied RF input power over the measured drive range, consistent with driven two-level dynamics under acoustic excitation. These results establish spin-acoustic resonance in a heterogeneously integrated molecular thin-film platform and provide a quantitative basis for benchmarking mechanically mediated spin control.
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Submitted 9 February, 2026;
originally announced February 2026.
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Phase engineering of 1T$'$ and 1T CrS2 and Cr2S3 by MOCVD
Authors:
Haoyu Bai,
Gareth R. M Tainton,
Mauro Och,
Max Rimmer,
Indrajit Maity,
Filippo Mione,
Khagesh Tanwar,
Rongsheng Cai,
Joseph Parker,
Kho Zhiquan,
Ercin C Duran,
Evan Tillotson,
Sam Sullivan-Allsop,
Alexander Eggeman,
Siyuan Deng,
Dan Bromley,
Jack N. Carter-Gartside,
Alex Vanstone,
Sandrine Heutz,
Will R. Branford,
Efrén Navarro-Moratalla,
Johannes C. Lischner,
Sarah Haigh,
Cecilia Mattevi
Abstract:
Layered Cr-chalcogenides compounds offer a rich range of crystal phases with different magnetic properties some of which have been predicted only but not experimentally verified. Here we demonstrate a previously unreported crystal phase of CrS2, namely the distorted octahedral (1T$'$) structure, synthesized via metal-organic chemical vapour deposition (MOCVD). We achieved the tuneable synthesis of…
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Layered Cr-chalcogenides compounds offer a rich range of crystal phases with different magnetic properties some of which have been predicted only but not experimentally verified. Here we demonstrate a previously unreported crystal phase of CrS2, namely the distorted octahedral (1T$'$) structure, synthesized via metal-organic chemical vapour deposition (MOCVD). We achieved the tuneable synthesis of either 1T$'$ or 1T phase CrS2. The structure were identified using polarized Raman spectroscopy, density functional perturbation theory (DFPT), as well as scanning electron diffraction (4D-STEM). 4D-STEM reveals that 1T$'$ crystals grow from an originally nucleated kinetically favoured 1T phase which then transform into the thermodynamically stable 1T$'$ phase. Magneto-optic Kerr imaging reveals that the 1T$'$ CrS2 crystals have soft ferromagnetic nature at low temperature. Our MOCVD growth of complex phases of 2D CrS2 with long-range magnetic order paves the way for the scalable synthesis of 2D magnets for ultrathin magnetic memories for logic-in-memory applications and spintronics.
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Submitted 9 October, 2025; v1 submitted 9 September, 2025;
originally announced September 2025.
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Factors Enabling Delocalized Charge-Carriers in Pnictogen-Based Solar Absorbers: In-depth Investigation into CuSbSe2
Authors:
Yuchen Fu,
Hugh Lohan,
Marcello Righetto,
Yi-Teng Huang,
Seán R. Kavanagh,
Chang-Woo Cho,
Szymon J. Zelewski,
Young Won Woo,
Harry Demetriou,
Martyn A. McLachlan,
Sandrine Heutz,
Benjamin A. Piot,
David O. Scanlon,
Akshay Rao,
Laura M. Herz,
Aron Walsh,
Robert L. Z. Hoye
Abstract:
Inorganic semiconductors based on heavy pnictogen cations (Sb3+ and Bi3+) have gained significant attention as potential nontoxic and stable alternatives to lead-halide perovskites for solar cell applications. A limitation of these novel materials, which is being increasingly commonly found, is carrier localization, which substantially reduces mobilities and diffusion lengths. Herein, the layered…
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Inorganic semiconductors based on heavy pnictogen cations (Sb3+ and Bi3+) have gained significant attention as potential nontoxic and stable alternatives to lead-halide perovskites for solar cell applications. A limitation of these novel materials, which is being increasingly commonly found, is carrier localization, which substantially reduces mobilities and diffusion lengths. Herein, the layered příbramite CuSbSe2 is investigated and discovered to have delocalized free carriers, as shown through optical pump terahertz probe spectroscopy and temperature-dependent mobility measurements. Using a combination of theory and experiment, it is found that the underlying factors are: 1) weak coupling to acoustic phonons due to low deformation potentials, as lattice distortions are primarily accommodated through rigid inter-layer movement rather than straining inter-atomic bonds, and 2) weak coupling to optical phonons due to the ionic contributions to the dielectric constant being low compared to electronic contributions. This work provides important insights into how pnictogen-based semiconductors avoiding carrier localization could be identified.
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Submitted 4 January, 2024;
originally announced January 2024.
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Controlling Ferromagnetic Ground States and Solitons in Thin Films and Nanowires built from Iron Phthalocyanine Chains
Authors:
Zhenlin Wu,
Peter Robaschik,
Luke R. Fleet,
Solveig Felton,
Gabriel Aeppli,
Sandrine Heutz
Abstract:
Iron phthalocyanine (FePc) is a molecular semiconductor whose building blocks are one-dimensional ferromagnetic chains. We show that its optical and magnetic properties are controlled by the growth strategy, obtaining extremely high coercivities of over 1 T and modulating the exchange constant between 15 and 29 K through tuning the crystal phase by switching from organic molecular beam deposition,…
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Iron phthalocyanine (FePc) is a molecular semiconductor whose building blocks are one-dimensional ferromagnetic chains. We show that its optical and magnetic properties are controlled by the growth strategy, obtaining extremely high coercivities of over 1 T and modulating the exchange constant between 15 and 29 K through tuning the crystal phase by switching from organic molecular beam deposition, producing continuous thin films of nanocrystals with controlled orientations, to organic vapour phase deposition, producing ultralong nanowires. Magnetisation measurements are analysed using a suite of concepts and simply stated formulas with broad applicability to all one-dimensional ferromagnetic chains. They show that FePc is best described by a Heisenberg model with a preference for the moments to lie in the molecular planes, where the chain Hamiltonian is very similar to that for the classic inorganic magnet CsNiF3, but with ferromagnetic rather than antiferromagnetic interchain interactions. The data at large magnetic fields are well-described by the soliton picture, where the dominant (and topologically non-trivial) degrees of freedom are moving one-dimensional magnetic domain walls, which was successful for CsNiF3, and at low temperatures and fields by the super-Curie-Weiss law of 1/(T^2+theta^2) characteristic of nearly one-dimensional xy and Heisenberg ferromagnets. The ability to control the molecular orientation and ferromagnetism of FePc systems, and produce them on flexible substrates as thin films or nanowires, taken together with excellent transistor characteristics reported previously for nanowires of copper and cobalt analogues, makes them potentially useful for magneto-optical and spintronic devices.
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Submitted 16 October, 2019;
originally announced October 2019.
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Multiple Quintets via Singlet Fission in Ordered Films at Room Temperature
Authors:
Daphné Lubert-Perquel,
Enrico Salvadori,
Matthew Dyson,
Paul N. Stavrinou,
Riccardo Montis,
Hiroki Nagashima,
Yasuhiro Kobori,
Sandrine Heutz,
Christopher W. M. Kay
Abstract:
The growing interest in harnessing singlet fission for photovoltaic applications stems from the possibility of generating two excitons from a single photon. Quantum efficiencies above unity have been reported, yet the correlation between singlet fission and intermolecular geometry is poorly understood. To address this, we investigated ordered solid solutions of pentacene in p-terphenyl grown by or…
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The growing interest in harnessing singlet fission for photovoltaic applications stems from the possibility of generating two excitons from a single photon. Quantum efficiencies above unity have been reported, yet the correlation between singlet fission and intermolecular geometry is poorly understood. To address this, we investigated ordered solid solutions of pentacene in p-terphenyl grown by organic molecular beam deposition. Two classes of dimers are expected from the crystal structure - parallel and herringbone - with intrinsically distinctive electronic coupling. Using electron paramagnetic resonance spectroscopy, we provide compelling evidence for the formation of distinct quintet excitons at room temperature. These are assigned to specific pentacene pairs according to their angular dependence. This work highlights the importance of controlling the intermolecular geometry and the need to develop adequate theoretical models to account for the relationship between structure and electronic interactions in strongly-coupled, high-spin molecular systems.
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Submitted 3 January, 2018; v1 submitted 2 January, 2018;
originally announced January 2018.
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Ultralong Copper Phthalocyanine Nanowires with New Crystal Structure and Broad Optical Absorption
Authors:
Hai Wang,
Soumaya Mauthoor,
Salahud Din,
Jules A. Gardener,
Rio Chang,
Marc Warner,
Gabriel Aeppli,
David W. McComb,
Mary P. Ryan,
Wei Wu,
Andrew J. Fisher,
A. Marshall Stoneham,
Sandrine Heutz
Abstract:
The development of molecular nanostructures plays a major role in emerging organic electronic applications, as it leads to improved performance and is compatible with our increasing need for miniaturisation. In particular, nanowires have been obtained from solution or vapour phase and have displayed high conductivity, or large interfacial areas in solar cells. In all cases however, the crystal str…
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The development of molecular nanostructures plays a major role in emerging organic electronic applications, as it leads to improved performance and is compatible with our increasing need for miniaturisation. In particular, nanowires have been obtained from solution or vapour phase and have displayed high conductivity, or large interfacial areas in solar cells. In all cases however, the crystal structure remains as in films or bulk, and the exploitation of wires requires extensive post-growth manipulation as their orientations are random. Here we report copper phthalocyanine (CuPc) nanowires with diameters of 10-100 nm, high directionality and unprecedented aspect ratios. We demonstrate that they adopt a new crystal phase, designated eta-CuPc, where the molecules stack along the long axis. The resulting high electronic overlap along the centimetre length stacks achieved in our wires mediates antiferromagnetic couplings and broadens the optical absorption spectrum. The ability to fabricate ultralong, flexible metal phthalocyanine nanowires opens new possibilities for applications of these simple molecules.
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Submitted 9 December, 2010;
originally announced December 2010.
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A Novel Route for the Inclusion of Metal Dopants in Silicon
Authors:
Jules A. Gardener,
Irving Liaw,
Gabriel Aeppli,
Ian W. Boyd,
Richard J. Chater,
Tim S. Jones,
David S. McPhail,
Gopinathan Sankar,
A. Marshall Stoneham,
Marcin Sikora,
Geoff Thornton,
Sandrine Heutz
Abstract:
We report a new method to introduce metal atoms into silicon wafers, using negligible thermal budget. Molecular thin films are irradiated with ultra-violet (UV) light releasing metal species into the semiconductor substrate. Secondary ion mass spectrometry (SIMS) and X-ray absorption spectroscopy (XAS) show that Mn is incorporated into Si as an interstitial dopant. We propose that our method can f…
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We report a new method to introduce metal atoms into silicon wafers, using negligible thermal budget. Molecular thin films are irradiated with ultra-violet (UV) light releasing metal species into the semiconductor substrate. Secondary ion mass spectrometry (SIMS) and X-ray absorption spectroscopy (XAS) show that Mn is incorporated into Si as an interstitial dopant. We propose that our method can form the basis of a generic low-cost, low-temperature technology that could lead to the creation of ordered dopant arrays.
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Submitted 8 March, 2010;
originally announced March 2010.
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Molecular Thin Films: a New Type of Magnetic Switch
Authors:
S. M. Heutz,
C. Mitra,
W. Wu,
A. J. Fisher,
A. Kerridge,
A. M. Stoneham,
A. H. Harker,
J. Gardener,
Hsiang-Han Tseng,
T. S. Jones,
C. Renner,
G. Aeppli
Abstract:
The design and fabrication of materials that exhibit both semiconducting and magnetic properties for spintronics and quantum computing has proven difficult. Important starting points are high-purity thin films as well as fundamental theoretical understanding of the magnetism. Here we show that small molecules have great potential in this area, due to ease of insertion of localised spins in organ…
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The design and fabrication of materials that exhibit both semiconducting and magnetic properties for spintronics and quantum computing has proven difficult. Important starting points are high-purity thin films as well as fundamental theoretical understanding of the magnetism. Here we show that small molecules have great potential in this area, due to ease of insertion of localised spins in organic frameworks and both chemical and structural purity. In particular, we demonstrate that archetypal molecular semiconductors, namely the metal phthalocyanines (Pc), can be readily fabricated as thin film quantum antiferromagnets, important precursors to a solid state quantum computer. Their magnetic state can be switched via fabrication steps which modify the film structure, offering practical routes into information processing. Theoretical calculations show that a new mechanism, which is the molecular analogue of the interactions between magnetic ions in metals, is responsible for the magnetic states. Our combination of theory and experiments opens the field of organic thin film magnetic engineering.
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Submitted 5 May, 2008;
originally announced May 2008.