Molecular nanomagnets hold great promise for spintronics and quantum technologies, provided that their spin memory can be preserved above liquid-nitrogen temperatures. In the past few years, the magnetic hysteresis records observed for two related dysprosocenium-type complexes have highlighted the potential of molecular engineering to decouple vibrational excitations from spin states and thereby enhance magnetic memory. Herein, we study the spin-vibrational coupling in [(Cp iPr5)­Dy­(Cp*)]+ (Cp iPr5 = pentaisopropylcyclopentadienyl, Cp* = pentamethylcyclopentadienyl), which currently holds the hysteresis record (80 K), by means of a computationally affordable methodology that combines first-principles electronic structure calculations with a phenomenological ligand field model. Our analysis is in good agreement with the previously reported state-of-the-art ab initio calculations, with the advantage of drastically reducing the computation time. We then apply the proposed methodology to three alternative dysprosocenium-type complexes, extracting physical insights that demonstrate the usefulness of this strategy to efficiently engineer and screen magnetic molecules with the potential of retaining spin information at higher temperatures.

Vibrations play a prominent role in magnetic relaxation processes of molecular spin qubits as they couple to spin states, leading to the loss of quantum information. Direct experimental determination of vibronic coupling is crucial to understand and control the spin dynamics of these nano-objects, which represent the limit of miniaturization for quantum devices. Herein, we measure the magneto-infrared properties of the molecular spin qubit system Na9[Ho­(W5O18)2]·35H2O. Our results place significant constraints on the pattern of crystal field levels and the vibrational excitations allowing us to unravel vibronic decoherence pathways in this system. We observe field-induced spectral changes near 63 and 370 cm–1 that are modeled in terms of odd-symmetry vibrations mixed with f-manifold crystal field excitations. The overall extent of vibronic coupling in Na9[Ho­(W5O18)2]·35H2O is limited by a modest coupling constant (on the order of 0.25) and a transparency window in the phonon density of states that acts to keep the intramolecular vibrations and M J levels apart. These findings advance the understanding of vibronic coupling in a molecular magnet with atomic clock transitions and suggest strategies for designing molecular spin qubits with improved coherence lifetimes.

We compare the electronic characteristics of nanowire field-effect transistors made using single pure wurtzite and pure zincblende InAs nanowires with nominally identical diameter. We compare the transfer characteristics and field-effect mobility versus temperature for these devices to better understand how differences in InAs phase govern the electronic properties of nanowire transistors.Copyright line will be provided by the publisher 1 Introduction The small volume and surface area of semiconductor nanowires enables high-quality interfaces that are difficult/impossible in bulk structures [1]. The InAs/InP [2] or Si/Ge [3] heterointerface is the classic example; however, crystal phase homointerfaces in a single semiconductor are also possible. In InAs nanowires these are the zincblende (ZB) phase observed in bulk III-Vs, and the wurtzite (WZ) phase [4]. This phase mixing is usually random and considerable effort has been invested into phase-engineered nanowires [5][6][7][8]. One key motivation is using the different band alignments [9-11] to make devices such as quantum dots [12,13]. Another is obtaining phase-pure WZ or ZB nanowires to prevent phase-interface scattering from degrading electrical performance [14,15].Studies of how nanowire crystal phase affects electrical properties are at an early stage. Dayeh et al. reported characterization at temperature T = 300 K of InAs nanowire field-effect transistors (NWFETs) made using pure ZB nanowires and WZ nanowires with small ZB segments interspersed axially (approx. 3.5 nm ZB per 28.5 nm WZ) [16]. While the mobility µ was comparable, the ZB NWFETs had higher off-current giving a poor on-off ratio I on /I off ∼ 2 compared to 10 4 for the WZ NWFETs. The difference was attributed to spontaneous

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