Magnetic and entanglement properties of molecular Cr<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mrow><mml:mn>2</mml:mn><mml:mi>n</mml:mi></mml:mrow></mml:msub></mml:math>Cu<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mrow /><mml:mn>2</mml:mn></mml:msub></mml:math>heterometallic spin rings

Lorusso, Giulia; Corradini, Valdis; Ghirri, Alberto; Biagi, Roberto; Pennino, U. del; Siloi, Ilaria; Troiani, Filippo; Timco, Grigore A.; Winpenny, R. E. P.; Affronte, Marco

doi:10.1103/physrevb.86.184424

Cited by 12 publications

(6 citation statements)

References 32 publications

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“…The XMCD signal is inherently weak relative to XAS; however with the development of lower temperature sample environments and higher applied magnetic fields, the use of L-edge XMCD for the study of paramagnetic and molecular based transition metal systems has shown a vibrant increase in recent years . The potential of XMCD has been demonstrated for the characterization of magnetic properties in molecule based magnets, in the bulk, and on surfaces. , In this study, XMCD measurements are used to provide an atomic specific measurement of magnetization, highlighting the presence of unpaired electrons within the 3d orbitals and their hybridization with ligand orbitals. Because these XMCD signals increase with applied magnetic field, we measure XMCD to high magnetic fields up to 21 T. Furthermore, DFT calculations are employed, based on the DP and MP crystal structures, to aid the analysis of our spectroscopic findings.…”

Section: Introductionmentioning

confidence: 99%

X-ray Magnetic Circular Dichroism Investigation of the Electron Transfer Phenomena Responsible for Magnetic Switching in a Cyanide-Bridged [CoFe] Chain

et al. 2013

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The cyanide-bridged [CoFe] one-dimensional chain, [Co(II)((R)-pabn)][Fe(III)(Tp)(CN)3](BF4)·MeOH·2H2O, where (R)-pabn = (R)-N2,N(2')-bis(pyridin-2-ylmethyl)-1,1'-binaphthyl-2,2'-diamine and Tp = hydrotris(pyrazolyl)borate, exhibits magnetic and electric bistabilities originating from an electron transfer coupled spin transition between Fe-CN-Co pairs. The use of L-edge X-ray absorption spectroscopy (XAS) in combination with L-edge X-ray magnetic circular dichroism (XMCD) is explored for the investigation of the electronic structure and magnetization of Co and Fe ions separately, in both diamagnetic and paramagnetic states. It has been established from susceptibility results that the switching between diamagnetic and paramagnetic phases emanates from electron transfer between low spin Fe(II) and Co(III), resulting in low spin Fe(III) (S = 1/2) and high spin Co(II) (S = 3/2). The XAS and XMCD results are consistent with the bulk susceptibility measurements, where greater detail regarding the charge transfer process is determined. The Fe-CN-Co electron transfer pathway is highlighted by a strongly XMCD dependent transition to a cyanide back bonding orbital, giving evidence for strong hybridization with Fe(III) t2g orbitals. In addition to thermally induced and photoinduced switching, [CoFe] is found to exhibit a switching by grinding induced dehydration. Analysis of XAS shows that on grinding diamagnetic [CoFe], 75% of metal ions lock into the magnetic Co(II)Fe(III) phase. Density functional theory calculations based on the [CoFe] crystal structure in the magnetic and nonmagnetic phases aid the spectroscopic results and provide a complementary insight into the electronic configuration of the [CoFe] 3d shells, quantifying the change in ligand field around Co and Fe centers on charge transfer.

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Section: Introductionmentioning

confidence: 99%

X-ray Magnetic Circular Dichroism Investigation of the Electron Transfer Phenomena Responsible for Magnetic Switching in a Cyanide-Bridged [CoFe] Chain

et al. 2013

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“…Finally, it is interesting to address the entanglement mechanism in the {Cr 10 } wheel, as an important asset for the application of these SMMs in quantum information technologies and for the interest in investigating quantum phenomena . Indeed, homometallic {Cr 8 } wheels and heterometallic {Cr 7 M} wheels have been the subject of numerous theoretical and experimental studies on different kinds of entanglement. − The {Cr 10 } case here presented is relevant, as it is essentially different from the previous homo- and heteronuclear-nuclear wheels previously considered in the literature, where AF interactions were dominant.…”

Section: Resultsmentioning

confidence: 98%

Origin of the Unusual Ground-State Spin S = 9 in a Cr₁₀ Single-Molecule Magnet

et al. 2022

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The molecular wheel [Cr10(OMe)20(O2CCMe3)10], abbreviated {Cr10}, with an unusual intermediate total spin S = 9 and non-negligible cluster anisotropy, D/k B = −0.045(2) K, is a rare case among wheels based on an even number of 3d-metals, which usually present an antiferromagnetic (AF) ground state (S = 0). Herein, we unveil the origin of such a behavior. Angular magnetometry measurements performed on a single crystal confirmed the axial anisotropic behavior of {Cr10}. For powder samples, the temperature dependence of the susceptibility plotted as χT(T) showed an overall ferromagnetic (FM) behavior down to 1.8 K, whereas the magnetization curve M(H) did not saturate at the expected 30 μB/fu for 10 FM coupled 3/2 spin Cr3+ ions, but to a much lower value, corresponding to S = 9. In addition, the X-ray magnetic circular dichroism (XMCD) measured at high magnetic field (170 kOe) and 7.5 K showed the polarization of the cluster moment up to 23 μB/fu. The magnetic results can be rationalized within a model, including the cluster anisotropy, in which the {Cr10} wheel is formed by two semiwheels, each with four Cr3+ spins FM coupled (J FM/k B = 2.0 K), separated by two Cr3+ ions AF coupled asymmetrically (J 23/k B = J 78/k B = −2.0 K; J 34/k B = J 89/k B = −0.25 K). Inelastic neutron scattering and heat capacity allowed us to confirm this model leading to the S = 9 ground state and first excited S = 8. Single-molecule magnet behavior with an activation energy of U/k B = 4.0(5) K in the absence of applied field was observed through ac susceptibility measurements down to 0.1 K. The intriguing magnetic behavior of {Cr10} arises from the detailed asymmetry in the molecule interactions produced by small-angle distortions in the angles of the Cr–O–Cr alkoxy bridges coupling the Cr3+ ions, as demonstrated by ab initio and density functional theory calculations, while the cluster anisotropy can be correlated to the single-ion anisotropies calculated for each Cr3+ ion in the wheel.

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“…Among various rings of antiferromagnetically coupled transition-metal ions, particular attention was devoted in the last years to the more restricted class of Cr-based systems [45]. The ability of tailoring the physical properties at the synthetic level (which was extensively demonstrated in these molecules) can also be regarded as a means for inducing different forms of entanglement [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Detection of multipartite entanglement in spin rings by use of exchange energy

Siloi

Troiani

2014

Phys. Rev. A

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We investigate multipartite entanglement in rings of arbitrary spins with antiferromagnetic interactions between nearest neighbors. In particular, we show that the nondegenerate ground state of rings formed by an even number (N ) of spins is N -partite entangled, and exchange energy can thus be used as a multipartite-entanglement witness. We develop a general approach to compute the energy minima corresponding to biseparable states, and provide numerical results for a representative set of systems. Despite its global character, exchange energy also allows a spin-selective characterization of entanglement. In particular, in the presence of a magnetic defect, one can derive separability criteria for each individual spin, and use exchange energy for detecting entanglement between this and all the other spins.

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Magnetic and entanglement properties of molecular Cr2nCu2heterometallic spin rings

Cited by 12 publications

References 32 publications

X-ray Magnetic Circular Dichroism Investigation of the Electron Transfer Phenomena Responsible for Magnetic Switching in a Cyanide-Bridged [CoFe] Chain

X-ray Magnetic Circular Dichroism Investigation of the Electron Transfer Phenomena Responsible for Magnetic Switching in a Cyanide-Bridged [CoFe] Chain

Origin of the Unusual Ground-State Spin S = 9 in a Cr₁₀ Single-Molecule Magnet

Detection of multipartite entanglement in spin rings by use of exchange energy

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Magnetic and entanglement properties of molecular Cr2nCu2heterometallic spin rings

Cited by 12 publications

References 32 publications

X-ray Magnetic Circular Dichroism Investigation of the Electron Transfer Phenomena Responsible for Magnetic Switching in a Cyanide-Bridged [CoFe] Chain

X-ray Magnetic Circular Dichroism Investigation of the Electron Transfer Phenomena Responsible for Magnetic Switching in a Cyanide-Bridged [CoFe] Chain

Origin of the Unusual Ground-State Spin S = 9 in a Cr10 Single-Molecule Magnet

Detection of multipartite entanglement in spin rings by use of exchange energy

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Product

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Origin of the Unusual Ground-State Spin S = 9 in a Cr₁₀ Single-Molecule Magnet