Search results for "spin state"
showing 10 items of 254 documents
Manipulation of the spin in single molecule magnets via Landau-Zener transitions
2011
We theoretically investigate the effects of a magnetic pulse on a single-molecule magnet (SMM) initially magnetized by a dc field along the easy axis of magnetization. In the Landau\char21{}Zener (LZ) scheme, it is shown that the final spin state is a function of the shape and duration of the pulse, conditioned by the decoherence time of the SMM. In the case of coherent tunneling, the asymmetric pulses are shown to reverse the direction of the magnetization, while the symmetric pulses can only decrease the value of the initial magnetization. It is also demonstrated that the application of an external variable dc field in the hard plane of magnetization provides the possibility to tune the r…
Insights on the coupling between vibronically active molecular vibrations and lattice phonons in molecular nanomagnets
2021
Spin-lattice relaxation is a key open problem to understand the spin dynamics of single-molecule magnets and molecular spin qubits. While modelling the coupling between spin states and local vibrations allows to determine the more relevant molecular vibrations for spin relaxation, this is not sufficient to explain how energy is dissipated towards the thermal bath. Herein, we employ a simple and efficient model to examine the coupling of local vibrational modes with long-wavelength longitudinal and transverse phonons in the clock-like spin qubit [Ho(W$_5$O$_{18}$)$_2$]$^{9-}$. We find that in crystals of this polyoxometalate the vibrational mode previously found to be vibronically active at …
Innentitelbild: Bidirectional Chemo‐Switching of Spin State in a Microporous Framework (Angew. Chem. 26/2009)
2009
Das chemische Schalten des Magnetismus in zwei Richtungen wurde in einem mikroporosen Koordinationspolymer mit Spin-Crossover-Einheiten beobachtet. M. Ohba, J. A. Real, S. Kitagawa und Mitarbeiter stellten in ihrer Zuschrift auf S. 4861 ff. magnetische Messungen vor, die belegen, dass die meisten Gastmolekule einen Ubergang des Netzwerks vom diamagnetischen Low-Spin- (rot) in den paramagnetischen High-Spin-Zustand (gelb) bewirken. Allein CS2 stabilisiert den Low-Spin-Zustand. Die induzierten Spinzustande werden auch nach Freisetzung der Gastspezies beibehalten.
Localization vs. Delocalization in Molecules and Clusters: Electronic and Vibronic Interactions in Mixed Valence Systems
1996
The interplay between electron delocalization and magnetic interactions play a key role in areas as diverse as solid state chemistry (bulk magnetic materials, superconductors,...) [1] and biology (iron-sulfur proteins, manganese-oxo clusters ...) [2]. In molecular inorganic chemistry these two electronic processes have been traditionally studied independently. Thus, the electron dynamics has been extensively investigated in mixedvalence dimers [3] as exemplified by the Creutz-Taube complex [(NH3)5RuII(pyrazine)RuIII(NH3)5]. In this kind of molecular complexes one extra electron is delocalized over two diamagnetic metal sites. Therefore, they constitute model systems for the study of the ele…
Chapter 23. Singlet Order in Heteronuclear Spin Systems
2020
The concept of heteronuclear Long-Lived spin States (LLSs) is introduced. In the simplest case of a pair of heteronuclei, such states are given by the singlet order of the spin pair, which can be efficiently sustained under Zero or Ultra-Low Field (ZULF) conditions. Here we describe two possible ways of detecting long-lived singlet order of heteronuclei: detection at ZULF conditions and NMR (Nuclear Magnetic Resonance) detection at high field utilising fast field-cycling. A theoretical description of the underlying spin dynamics is presented for both cases; the discussion is supported by experimental examples of LLSs in 13CH groups. The generality of these phenomena is discussed, as well as…
Light-Induced Excited Spin State Trapping in Iron(II) Complexes
1987
In the course of our studies on the thermally induced high spin (HS) ↔ low spin (LS) transition in iron(II) complexes /1/, \({\!^5{\text{T}}_2}_{\text{g}}\) ↔ \({\!^1{\text{A}}_1}_{\text{g}}\) in the approximation of Oh symmetry, we have observed in 1984 a new photophysical effect /2/: If, at sufficiently low temperature, the solid spin crossover complex is irradiated with green light into the \({\!^1{\text{A}}_1}\)→ \({\!^1{\text{T}}_1}\) ligand field absorption band, the thermodynamically stable LS state can be converted to the metastable HS state and trapped with practically infinite lifetime. We have called this unusual phenomenon “Light-Induced Excited Spin State Trapping (LIESST)”.
In Silico Molecular Engineering of Dysprosocenium-Based Complexes to Decouple Spin Energy Levels from Molecular Vibrations
2019
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 [(CpiPr5)Dy(Cp*)]+ (CpiPr5 = pentaisopropylcyclopentadienyl, Cp* = pentamethylcyclopentadienyl), which currently holds the hysteresis record (80 K), by means of a computationally affordable methodology that combines first-pri…
First observation of trapped high-field seeking ultracold neutron spin states
2011
Ultracold neutrons were stored in a volume, using a magnetic dipole field shutter. Radial confinement was provided by material walls. Low-field seeking neutrons were axially confined above the magnetic field. High-field seeking neutrons are trapped inside the magnetic field. They can systematically shift the measured neutron lifetime to lower values in experiments with magnetic confinement. ISSN:0370-2693 ISSN:0031-9163 ISSN:1873-2445
Triaxial shape with rotation around the longest principal axis inGd142
2008
The cranking model is used to describe rotational bands. We investigate the approach of using diabatic configurations and minimizing the particle-number projected energy in a mesh of both lambda, Delta and deformation parameters. We use the method to interpret recent experimental data in Gd-142 and conclude that for the highest spin states observed (I approximate to 30), the nucleus is triaxial and builds spin by rotating around the classically unfavored longest axis.
Decay properties of very-high-spin states in transitional Er nuclei aroundA=154
1986
Theγ ray continuum structures of the transitional Er isotopes withA∼154 are studied using the reaction74Ge(84Kr,xn)158−xEr atElab=340 MeV. The measurements include energy spectra, total energies, multiplicities, angular distributions and lifetimes using the DSAM method. The analysis of data confirms the previously observed two-bump structure of the continuum radiation. A meticulous subtraction of discrete contributions proves the persistence of the low-energy bump even at high spins, i.e.I>40ħ. The angular-distribution measurements assign predominant dipole structure to the bump atEγ=0.65 MeV, whereas the bump atEγ=1.3 MeV is of almost pure quadrupole character at high spins. The lifetime m…