arXiv subjects

Eufemio Moreno-Pineda

Publications and source records attributed to Eufemio Moreno-Pineda.

4 recordsLinked to original sources

arXiv2026

Fast Nuclear Spin Read-Out in Single Molecule Magnets

Nuclear spins in 4f single-molecule magnets (SMMs) are promising qubits or qudits candidates for quantum information processing due to their relative isolation and reduced susceptibility to environmental disturbances, while their hyperfine coupling to the 4f magnetic moments enable readout and control. So far, the nuclear spin states of individual TbPc2 SMMs have been detected in transport measurements via the spin-cascade effect. Here, we demonstrate a fast, field-sweep-free readout of nuclear spin in individual 163DyPc2 (I = 5/2) and 159TbPc2 (I = 3/2) using millikelvin spin-polarized scanning tunneling microscopy. This fast readout is enabled by the hyperfine interactions, which modifies the statistics of the telegraph noise generated by reversals of the Ln3+ moment, thereby revealing the nuclear spin state. We observe nuclear spin relaxation times T1 in excess of minutes. Furthermore, we drive nuclear spin transitions using a radio-frequency field and detect the resulting nuclear magnetic resonance directly in the tunneling current. Thus our approach enables fast access to long-lived nuclear spin states in an individual molecule

cond-mat.mes-hall↗

arXiv2021

Magnetic properties of transition metal dimers probed by inelastic neutron scattering

The physical characterisation and understanding of molecular magnetic materials is one of the most important steps towards the integration of such systems in hybrid spintronic devices. Amongst the many characterisation techniques employed in such a task, Inelastic Neutron Scattering (INS) stands as one of the most powerful and sensitive tools to investigate their spin dynamics. Herein, the magnetic properties and spin dynamics of two dinuclear complexes, namely [(M(hfacac)$_2$)$_2$(bpym)] (where M = Ni$^{2+}$, Co$^{2+}$, abbreviated in the following as Ni$_2$, Co$_2$) are reported. These are model systems that could constitute fundamental units of future spintronic devices. By exploiting the highly sensitive IN5 Cold INS spectrometer, we are able to gain a deep insight into the spin dynamics of Ni$_2$ and to fully obtain the microscopic spin Hamiltonian parameters; while for Co$_2$, a multitude of INS transitions are observed demonstrating the complexity of the magnetic properties of octahedral cobalt-based systems.

cond-mat.mes-hall↗

arXiv2020

Observation of Cooperative Electronic Quantum Tunneling: Increasing Accessible Nuclear States in a Molecular Qudit

As an extension of two-level quantum bits (qubits), multilevel systems, so-called qudits, where d represents the Hilbert space dimension, have been predicted to reduce the number of iterations in quantum computation algorithms. This has been tested in the well-known [TbPc2]0 SMM, which allowed the implementation of the Grover algorithm in a single molecular unit. In the quest for molecular systems possessing an increased number of accessible nuclear spin states, we explore herein a dimeric Tb2-SMM via single crystal μ-SQUID measurements at sub-Kelvin temperatures. We observe ferromagnetic interactions between the Tb(III) ions and cooperative quantum tunneling of the electronic spins with spin ground state \textit{J} = {\pm}6. The strong hyperfine coupling with the Tb(III) nuclear spins leads to a multitude of spin reversal paths leading to seven strong hyperfine driven tunneling steps in the hysteresis loops. Our results show the possibility to read-out the Tb(III) nuclear spin states via the cooperative tunneling of the electronic spins, making the dimeric Tb2-SMM an excellent nuclear spin qudit candidate with d =16.

quant-ph↗

arXiv2017

Molecular Spin Qudits for Quantum Algorithms

Presently, one of the most ambitious technological goals is the development of devices working under the laws of quantum mechanics. One prominent target is the quantum computer, which would allow the processing of information at quantum level for purposes not achievable with even the most powerful computer resources. The large-scale implementation of quantum information would be a game changer for current technology, because it would allow unprecedented parallelised computation and secure encryption based on the principles of quantum superposition and entanglement. Currently, there are several physical platforms racing to achieve the level of performance required for the quantum hardware to step into the realm of practical quantum information applications. Several materials have been proposed to fulfil this task, ranging from quantum dots, Bose-Einstein condensates, spin impurities, superconducting circuits, molecules, amongst others. Magnetic molecules are among the list of promising building blocks, due to (i) their intrinsic monodispersity, (ii) discrete energy levels (iii) the possibility of chemical quantum state engineering, and (iv) their multilevel characteristics, leading to the so called Qudits (d > 2), amongst others. Herein we review how a molecular multilevel nuclear spin qubit (or qudit, where d = 4), known as TbPc2, gathers all the necessary requirements to perform as a molecular hardware platform with a first generation of molecular devices enabling even quantum algorithm operations.

quant-ph↗