0000000000021958
AUTHOR
James S. Lord
Hysteresis in the spin transition regime of [Fe(NH2trz)3](NO3)2 as probed by ZF-μSR
The thermal spin transition which occurs in the polymeric chain compound [Fe(NH(2)trz)(3)](NO3)(2) above room temperature has been investigated by zero-field muon spin relaxation (mu SR) (similar to 8-402 K). The depolarization curves are best described by a Lorentzian and a Gaussian line that represent fast and slow components respectively. The spin transition is associated with a hysteresis loop of width Delta T = 34 K (T-1/2(up arrow) = 346 K and T-1/2(down arrow) = 312 K) that has been delineated by the temperature variation of the initial asymmetry parameter. Comparison of zero-field and transverse field (20 Oe) mu SR measurements shows that diamagnetic muon species occur over the enti…
Importance of Spin-Orbit Interaction for the Electron Spin Relaxation in Organic Semiconductors
Despite the great interest organic spintronics has recently attracted, there is only a partial understanding of the fundamental physics behind electron spin relaxation in organic semiconductors. Mechanisms based on hyperfine interaction have been demonstrated, but the role of the spin-orbit interaction remains elusive. Here, we report muon spin spectroscopy and time-resolved photoluminescence measurements on two series of molecular semiconductors in which the strength of the spin-orbit interaction has been systematically modified with a targeted chemical substitution of different atoms at a particular molecular site. We find that the spin-orbit interaction is a significant source of electro…
Muon spin relaxation studies of iron(II) spin crossover complexes
A series of model iron(II) spin crossover complexes have been investigated by temperature dependent muon spin relaxation (mu SR) techniques at ISIS, UK. The thermally induced spin crossover in these materials could be monitored by following the initial asymmetry parameter, a(0), in zero-field. We established that the behavior of a(0) correlates well with the shape of the spin crossover curve derived from magnetic susceptibility measurements, whether hysteretic, smooth, or abrupt. In addition, the longitudinal field dependence of a(0) not only provides information on the nature of the muonic species but also on their interactions and respective localization in the crystal lattice. Useful ins…
Spin transition in [Fe(phen)2(NCS)2] - �SR study
The reversible thermal spin transition which occurs in [Fe(phen)(2)(NCS)(2)] around T-1/2 similar to 177 K has been investigated by muon spin relaxation (muSR) (similar to10-280 K). The depolarisation curves are well described by two Lorentzian lines represent fast and slow components in the decay curves, with the initial asymmetry parameter of the fast component found to track the spin transition in [Fe(phen)2(NCS),]. Comparison of zero-field and transverse field (20 Oe) muSR measurements shows that diamagnetic muonic species occur over the entire temperature range.
Spin Crossover in Fe(II) Molecular Compounds — Mössbauer and µSR Investigations
The compound [Fe(ptz)6](C104)2 (ptz = 1-propyl-tetrazole) displays a complete and gradual spin crossover centred around 125 K as evidenced by magnetic and muon measurements over the temperature range ∼ 4.2–300 K. Although the crystal structure reveals only one crystallographic site, line broadening is observed in the Mossbauer spectra in the vicinity of the spin transition. The muon spin relaxation behaviour of this compound indicates that a structural transformation rather than dynamic processes may account for the observed spectral features. Both the Mossbauer and muon measurements are consistent with a mixture of high and low spin Fe ions in the transition region.