Several technological issues have to be faced to realize devices working at the single molecule level. One of the main challenges consists of defining methods to fabricate electrodes to make contact with single molecules. Here, we report the realization of novel spintronic devices made of a TbPc₂ single molecule embedded between two nanometer-separated graphene electrodes, obtained by feedback-controlled electroburning. We demonstrate that this approach allows the realisation of devices working at low temperature. With these, we were able to characterize the magnetic exchange coupling between the electronic spin of the Tb³⁺ magnetic core and the current passing through the molecular system in the Coulomb blockade regime, thus showing that the use of graphene is a promising way forward in addressing single molecules.

This manuscript discusses the difficulties with magnetic position and orientation (MPO) system design and proposes a general method for finding optimal layouts. The formalism introduces a system quality measure through state separation and reduces the question “How to design an MPO system?” to a global optimization problem. The latter is then solved by combining differential evolution algorithms with magnet shape variation based on analytical computations of the field. The proposed formalism is then applied to study possible realizations of continuous three-axis joystick motion tracking, realized with just a single magnet and a single 3D magnetic field sensor. The computations show that this is possible when a specific design condition is fulfilled and that large state separations as high as $1\mathrm{mT}{/}^{\circ }$ can be achieved under realistic conditions. Finally, a comparison to state-of-the-art design methods is drawn, computation accuracy is reviewed critically, and an experimental validation is presented.

The dynamics of a quantum system in a dissipative environment presents a rich and still largely unexplored phenomenology that is relevant for the control of quantum devices. The simplest problem can be modeled as a two-level system—such as a spin—in contact with a thermal bath. Here, we present experiments in which we monitor the spin reversal in a TbPc2 single-molecule spin transistor, and we show that the application of microwave pulses can cause the spin to flip between its two lowest-lying states (|↑⟩ and |↓⟩) at a rate that increases with increasing duration and power of the pulses. This process is neither resonant nor coherent with the microwave pulses. Moreover, an asymmetry appears in the |↓⟩→|↑⟩ and |↑⟩→|↓⟩ transition probabilities, suggesting that the process occurs out of equilibrium. We explain the experimental results and provide an estimate of the local temperature increase induced by the microwave pulses by means of a model that takes into account the energy exchange between the single Tb3+ electron spin and the local environment. This work is partially supported by the MolSpin COST Action 15128, by the French National Agency of Research through the ANR-13-BS10-0001 MolQuSpin, by the European Community through the FET-Proactive Project MoQuaS (Contract No. 610449), by the German Research Foundation (DFG) through the Transregio Project No. TR88 3MET, by the Alexander von Humboldt Foundation, and by the Italian Ministry for Research (MIUR) through the FIR Grant No. RBFR13YKWX. The samples were fabricated at the NANOFAB facility of the Néel Institute. The authors acknowledge the fruitful collaboration with E. Eyraud, Y. Deschanels, D. Lepoittevin, C. Hoarau, and C. Thirion for experimental setup and software development.

Graphene nanodevices, such as ultra-narrow constrictions and nanometer-spaced gaps, are emerging as appealing candidates for various applications, ranging from advanced quantum devices to single-molecule junctions and even DNA sequencing. Here, we present the realization and characterization of nanometer-sized gaps in suspended few-layer graphene devices via feedback-controlled electroburning at room temperature. By analyzing the electrical behavior after the electroburning process, we identify two distinct regimes for the resulting devices, deriving a simple yet effective quantitative criterion to determine the complete opening of the nanogaps.

The quantitative description of electrical and magnetotransport properties of solid-state materials has been a remarkable challenge in materials science over recent decades. Recently, the discovery of a novel class of materials—the topological semimetals—has led to a growing interest in the full understanding of their magnetotransport properties. In this review, the strong interplay among topology, band structure, and carrier mobility in recently discovered high carrier mobility topological semimetals is discussed and their effect on their magnetotransport properties is outlined. Their large magnetoresistance effect, especially in the Hall transverse configuration, and a new version of a three-dimensional quantum Hall effect observed in high-mobility Weyl and Dirac semimetals are reviewed. The possibility of designing novel quantum sensors and devices based on solid-state semimetals is also examined.

A non-invasive implementation of a planar magnetoresistive sensor on top of copper interconnected power modules is proposed. This solution allows for the real-time monitoring of the electrical current flowing across the power modules. Anisotropic magnetoresistive (AMR) sensors made of Permalloy were designed through finite-difference and finite-element simulations in the so-called barber-pole configuration and microfabricated via patterning by laser lithography and thin film deposition by electron-beam evaporation. Finally, the sensor performance was tested by measuring the magnetic field generated by the electrical current in a specific range of interest.