Single molecule magnets sublimated on conducting and magnetic substrates

Single Molecule Magnets (SMMs) showing bistability and quantum phenomena are promising candidates for spintronic applications. In recent years, the study of hybrid surfaces composed of SMMs on conductive and magnetic surfaces has attracted increasing interest. In this work the preparation of hybrid surfaces made by terbium bis(phthalocyaninato) and Fe4 SMMs is reported. The surfaces were structurally and magnetically characterized by means of laboratory and large scale facility techniques. This investigation has provided interesting hints towards their application in spintronic devices and has paved the way for the magnetic characterization of Fe4 at the single molecule level

Non-locally sensing the magnetic states of nanoscale antiferromagnets with an atomic spin sensor

The ability to sense the magnetic state of individual magnetic nano-objects is a key capability for powerful applications ranging from readout of ultra-dense magnetic memory to the measurement of spins in complex structures with nanometer precision. Magnetic nano-objects require extremely sensitive sensors and detection methods. Here we create an atomic spin sensor consisting of three Fe atoms and show that it can detect nanoscale antiferromagnets through minute surface-mediated magnetic interaction. Coupling, even to an object with no net spin and having vanishing dipolar stray field, modifies the transition matrix element between two spin states of the Fe-atom-based spin sensor that changes the sensor's spin relaxation time. The sensor can detect nanoscale antiferromagnets at up to three nanometers distance and achieves an energy resolution of 10 micro-electronvolts surpassing the thermal limit of conventional scanning probe spectroscopy. This scheme permits simultaneous sensing of multiple antiferromagnets with a single spin sensor integrated onto the surface.Comment: 30 pages main text, 6 figures, Supplementary materials not inculde

UHV Deposition and Characterization of a Mononuclear Iron(III) \u3b2-diketonate Complex on Au(111)

The adsorption of the sterically hindered \u3b2-diketonate complex Fe(dpm)3, where Hdpm = dipivaloylmethane, on Au(111) was investigated by ultraviolet photoelectron spectroscopy (UPS) and scanning tunnelling microscopy (STM). The high volatility of the molecule limited the growth of the film to a few monolayers. While UPS evidenced the presence of the \u3b2-diketonate ligands on the surface, the integrity of the molecule on the surface could not be assessed. The low temperature STM images were more informative and at submonolayer coverage they showed the presence of regular domains characterized by a flat morphology and height of 480.3 nm. Along with these domains, tetra-lobed features adsorbed on the kinks of the herringbone were also observed. DFT-simulated images of the pristine molecule and its possible decomposition products allowed to assess the partial fragmentation of Fe(dpm)3 upon adsorption on the Au(111) surface. Structural features with intact molecules were only observed for the saturation coverage. An ex situ prepared thick film of the complex was also investigated by X-ray magnetic circular dichroism (XMCD) and features typical of high-spin iron(III) in octahedral environment were observed

Magnetic fingerprint of individual Fe4 molecular magnets under compression by a scanning tunnelling microscope

Single-molecule magnets (SMMs) present a promising avenue to develop spintronic technologies. Addressing individual molecules with electrical leads in SMM-based spintronic devices remains a ubiquitous challenge: interactions with metallic electrodes can drastically modify the SMM\u2019s properties by charge transfer or through changes in the molecular structure. Here, we probe electrical transport through individual Fe4 SMMs using a scanning tunnelling microscope at 0.5 K. Correlation of topographic and spectroscopic information permits identification of the spin excitation fingerprint of intact Fe4 molecules. Building from this, we find that the exchange coupling strength within the molecule\u2019s magnetic core is significantly enhanced. First-principles calculations support the conclusion that this is the result of confinement of the molecule in the two-contact junction formed by the microscope tip and the sample surface

Single molecule magnets sublimated on conducting and magnetic substrates

Single Molecule Magnets (SMMs) showing bistability and quantum phenomena are promising candidates for spintronic applications. In recent years, the study of hybrid surfaces composed of SMMs on conductive and magnetic surfaces has attracted increasing interest. In this work the preparation of hybrid surfaces made by terbium bis(phthalocyaninato) and Fe4 SMMs is reported. The surfaces were structurally and magnetically characterized by means of laboratory and large scale facility techniques. This investigation has provided interesting hints towards their application in spintronic devices and has paved the way for the magnetic characterization of Fe4 at the single molecule level

Single molecule magnets sublimated on conducting and magnetic substrates

Single Molecule Magnets (SMMs) showing bistability and quantum phenomena are promising candidates for spintronic applications. In recent years, the study of hybrid surfaces composed of SMMs on conductive and magnetic surfaces has attracted increasing interest. In this work the preparation of hybrid surfaces made by terbium bis(phthalocyaninato) and Fe4 SMMs is reported. The surfaces were structurally and magnetically characterized by means of laboratory and large scale facility techniques. This investigation has provided interesting hints towards their application in spintronic devices and has paved the way for the magnetic characterization of Fe4 at the single molecule level

Erratic magnetic hysteresis of TbPc2 molecular nanomagnets

Terbium(iii) bis-phthalocyaninato neutral complex, a robust and evaporable Single Molecule Magnet (SMM) with a record height of the anisotropy barrier, has recently attracted a great interest as an active unit in single molecule electronics, but at the same time its magnetic hysteresis has been found to be strongly affected when the environment is different from the crystalline phase. Here we present a systematic investigation of the magnetization dynamics in different environments, obtained by magnetic dilution, thermal treatment and sublimation of the molecules, to shed some light on the origin of the evanescence of the hysteretic behavior of this unique SMM. © 2013 The Royal Society of Chemistry

Structure, magnetic properties and thermal sublimation of fluorinated Fe4 Single-Molecule Magnets

Fluorinated tetrairon(III) Single-Molecule Magnets (SMMs) [Fe4(L1)2(dpmF6)6] (1dpmF6), [Fe4(L2)2(dpmF6)6] (2dpmF6), and [Fe4(L2)2(pta)6] (2pta) were assembled combining the tripodal ligands H3L1 = 2-hydroxymethyl-2-phenylpropane-1,3-diol and H3L2 = S-5-hydroxy-4,4-bis(hydroxymethyl)pentyl ethanethioate with fluorinated β-diketones analogues of dipivaloylmethane (Hdpm), namely 1,1,1-trifluoro-2,6,6-trimethyl-2-(trifluoromethyl)heptane-3,5-dione (HdpmF6) and pivaloyltrifluoroacetone (Hpta). The new compounds, along with [Fe4(L1)2(dpm)6] (1dpm) and [Fe4(L1)2(pta)6] (1pta), were designed in order to investigate the effect of fluorination degree on processability by thermal sublimation. The two different functional groups on the tripodal ligands, i.e. C6H5 in H3L1 and (CH2)3SAc in H3L2, are suitable for promoting physisorption and chemisorption on surfaces, respectively. Direct current magnetic data are typical for the metal-centred triangular topology of Fe4 complexes, with antiferromagnetic nearest-neighbour coupling constants in the range 16–18 cm−1 and an S = 5 ground spin state. Alternating current susceptibility measurements showed that slow magnetic relaxation persists in fluorinated compounds. When heated in high vacuum (10−7 mbar), 2dpmF6 and 2pta undergo thermal decomposition before subliming, while 1dpmF6 was found to sublimate at 497 ± 5 K in the same conditions, being the third sublimable SMM of this family after 1pta (440 ± 5 K) and 1dpm (500 ± 10 K)

Imaging conformations of holo- and apo-transferrin on the single-molecule level by low-energy electron holography

Abstract Conformational changes play a key role in the biological function of many proteins, thereby sustaining a multitude of processes essential to life. Thus, the imaging of the conformational space of proteins exhibiting such conformational changes is of great interest. Low-energy electron holography (LEEH) in combination with native electrospray ion beam deposition (ES-IBD) has recently been demonstrated to be capable of exploring the conformational space of conformationally highly variable proteins on the single-molecule level. While the previously studied conformations were induced by changes in environment, it is of relevance to assess the performance of this imaging method when applied to protein conformations inherently tied to a function-related conformational change. We show that LEEH imaging can distinguish different conformations of transferrin, the major iron transport protein in many organisms, by resolving a nanometer-scale cleft in the structure of the iron-free molecule (apo-transferrin) resulting from the conformational change associated with the iron binding/release process. This, along with a statistical analysis of the data, which evidences a degree of flexibility of the molecules, indicates that LEEH is a viable technique for imaging function-related conformational changes in individual proteins