Peculiarities of isotopic temperatures obtained from p+A collisions at 1 GeV

Nuclear temperatures obtained from inclusive measurements of double isotopic yield ratios of fragments produced in 1 GeV p + A collisions amount to about 4 MeV nearly independent from the target mass.Comment: 4 pages, 4 figures, to be submitted to Eur. Phys. J.

Extrapolation of neutron-rich isotope cross-sections from projectile fragmentation

Using the measured fragmentation cross sections produced from the 48Ca and 64Ni beams at 140 MeV per nucleon on 9Be and 181Ta targets, we find that the cross sections of unmeasured neutron rich nuclei can be extrapolated using a systematic trend involving the average binding energy. The extrapolated cross-sections will be very useful in planning experiments with neutron rich isotopes produced from projectile fragmentation. The proposed method is general and could be applied to other fragmentation systems including those used in other radioactive ion beam facilities.Comment: accepted for publication in Europhysics Letter

An X- and Q-band Gd 3 EPR study of a single crystal of EuAlO 3: EPR linewidth variation with temperature and low-symmetry effects

Detailed electron paramagnetic resonance (EPR) studies on a single crystal of Gd 3-doped Van-Vleck compound EuAlO 3, potentially a phosphorescent/luminescent/laser material, with the Gd 3 ion substituting for the Eu 3 ion, were carried out at X-band (9.2 GHz) over the 77400 K temperature range. They provide new physical results on magnetic properties of the Eu 3 ion in a low symmetry environment. The asymmetry exhibited by the variation of the Gd 3 EPR line positions for the orientations of the external magnetic field about the Z and X magnetic axes in the ZX plane was ascribed to the existence of low, monoclinic, site symmetry, as revealed by the significant values of the spin-Hamiltonian (SH) parameters b41 and b43, estimated by fitting all the observed EPR line positions at room temperature for the orientation of the magnetic field in the magnetic ZX plane using a least-square fitting procedure. The temperature dependence of the Gd 3 EPR linewidth is interpreted to be due to the life-time broadening, caused by dynamical exchange and dipolar interactions between the impurity Gd 3 ions and the host Eu 3 ions. © 2012 Elsevier B.V. All rights reserved

EPR study of solid solutions La1-0.33yBa0.33yMn yAl1-yO3 (y = 0.02, 0.04, 0.10)

Abstract-Solid solutions La1-0.33yBa0.33yM nyAl1-yO3 (y = 0.02, 0.04, 0.10) prepared using the ceramic technique have been investigated by the EPR method at temperatures of 77 and 300 K. By comparing with the calculated spectra, the experimental spectra have been assigned to Mn2+ ions (g = 2.04 and line width δHpp = 64 × 10-4 T at T=77K) and Mn 4+ ions (g = 1.97 and δHpp = 76 × 10 -4 T at T = 77 K) and the broad line (δHpp = 500 × 10-4 T at T = 77 K) has been attributed to clusters. The dilution of manganese ions as a result of the dissolution of La 0.67Ba0.33MnO3 in LaAlO3 has allowed one to trace the cluster formation and the spin dynamics of Mn ions. It has been established that, at room temperature, compared to the system in which the Sr2+ ion with a smaller ionic radius is the replacing element, the localized states are more stable at all three manganese concentrations (the EPR lines are more intense). The La0.67Ba0.33MnO3 clusters dissolved in LaAlO3 retain some properties of a concentrated compound even upon dilution to y = 0.02. © Pleiades Publishing, Ltd., 2010

Spin relaxation of Mn ions in rare earth manganites in paramagnetic region

Role of bottlenecked spin relaxation and proportionality between small polaron hopping conductivity and electron paramagnetic resonance (EPR) linewidth (intensity) was emphasized. This idea gave a background for several experimental and theoretical investigations and it was starting point for its further generalization on variable range hopping conductivity and its influence on EPR linewidth in rare earth manganites. © Kazan Federal University (KFU)

An X- and Q-band Gd3+ EPR study of a single crystal of EuAlO3: EPR linewidth variation with temperature and low-symmetry effects

Detailed electron paramagnetic resonance (EPR) studies on a single crystal of Gd3+-doped Van-Vleck compound EuAlO3, potentially a phosphorescent/luminescent/laser material, with the Gd3+ ion substituting for the Eu3+ ion, were carried out at X-band (9.2 GHz) over the 77–400 K temperature range. They provide new physical results on magnetic properties of the Eu3+ ion in a low symmetry environment. The asymmetry exhibited by the variation of the Gd3+ EPR line positions for the orientations of the external magnetic field about the Z and X magnetic axes in the ZX plane was ascribed to the existence of low, monoclinic, site symmetry, as revealed by the significant values of the spin-Hamiltonian (SH) parameters and , estimated by fitting all the observed EPR line positions at room temperature for the orientation of the magnetic field in the magnetic ZX plane using a least-square fitting procedure. The temperature dependence of the Gd3+ EPR linewidth is interpreted to be due to the “life-time” broadening, caused by dynamical exchange and dipolar interactions between the impurity Gd3+ ions and the host Eu3+ ions

A Review of EPR Studies on Magnetization of Nanoparticles of Dilute Magnetic Semiconductors Doped by Transition-Metal Ions

© 2015, Springer-Verlag Wien. This article reviews recent electron paramagnetic resonance (EPR) studies on the magnetic properties of nanoparticles of dilute magnetic oxide semiconductors (DMS) doped with transition-metal ions. These nanoparticles are SnO2 doped with Co2+, Fe3+, Cr3+ ions, CeO2 doped with Ni2+, Co2+ ions, and ZnO doped with Fe3+ ions. The EPR studies reveal that the method of synthesis, surface properties, and size of nanoparticles are important factors that determine the magnetic properties of DMS nanoparticles. In addition, they indicate that ferromagnetic and paramagnetic phases may coexist. The saturation magnetization, as estimated from EPR signal, depends both on the doping level of impurities and annealing temperature. Undoped DMS also exhibit ferromagnetism due to oxygen vacancies. Furthermore, the EPR spectrum depends very sensitively on the size of nanoparticle

A 236-Ghz Fe\u3csup\u3e3+\u3c/sup\u3e EPR Study of Nanoparticles of the Ferromagnetic Room-Temperature Semiconductor Sn\u3csub\u3e1-x\u3c/sub\u3eFe\u3csub\u3ex\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e (\u3cem\u3ex\u3c/em\u3e = 0.005)

High-frequency (236 GHz) electron paramagnetic resonance (EPR) studies of Fe3+ ions at 255 K are reported in a Sn1-xFexO2 powder with x = 0.005, which is a ferromagnetic semiconductor at room temperature. The observed EPR spectrum can be simulated reasonably well as the overlap of spectra due to four magnetically inequivalent high-spin (HS) Fe3+ ions (S = 5/2). The spectrum intensity is calculated, using the overlap I(BL) + (I(HS1) + I(HS2) + I(HS3) + I(HS4)) 9 x e-0.00001xB, where B is the magnetic field intensity in Gauss, I represents the intensity of an EPR line (HS1, HS2, HS3, HS4), and BL stands for the base line (the exponential factor, as found by fitting to the experimental spectrum, is related to the Boltzmann population distribution of energy levels at 255 K, which is the temperature of the sample in the spectrometer). These high-frequency EPR results are significantly different from those at X-band. The large values of the zero-field splitting parameter (D) observed here for the four centers at the high frequency of 236 GHz are beyond the capability of X-band, which can only record spectra of ions only with much smaller D values than those reported here

EPR/FMR Investigation of Mn-Doped SiCN Ceramics

SiCN magnetic ceramics doped with Mn 2+ ions were synthesized at the pyrolysis temperature of 1,100°C, using CERASET™ as liquid polymer precursor and polymer manganese(II) acetylacetonate as dopant, and investigated by electron paramagnetic resonance (EPR)/ferromagnetic resonance (FMR) technique. The predominant source of ferromagnetism in SiCN samples doped with Mn ions, as synthesized here, is the ensemble of ferromagnetic nanoparticles of Mn 5Si 3C x incorporated into the amorphous SiC/Mn structure. The fluctuation of magnetization due to ferromagnetic Mn 5Si 3C x particles significantly broadens the EPR lines at the phase-transition temperature (363 K). This is the first fabrication of a SiCN/Mn ceramic, which exhibits room-temperature ferromagnetism. © 2010 Springer-Verlag

An X- and Q-band Fe3+ EPR study of nanoparticles of magnetic semiconductor Zn1-xFexO

EPR studies on two types of nanoparticles of Fe3+ doped, 0.1-10%, ZnO, NL and QJ, prepared using similar chemical hydrolysis methods, in diethylene glycol, and in denatured ethanol solutions, respectively, were carried out at X-band (~9.5 GHz) at 77 K and at Q-band (~34.0 GHz) at 10, 80, and 295 K. To interpret the experimental results, EPR spectra were simulated by exact diagonalization of the spin-Hamiltonian matrix to identify the Fe ions at different magnetically active sites in these samples. The simulation for NL samples revealed that they contained (i) Fe3+ ions, which substituted for Zn ions, the zero-field splitting (ZFS) parameter which has a large distribution over the sample due to oxygen vacancies in the second coordination sphere; (ii) EPR signal from surface oxygen defects; and (iii) ferromagnetically (FM) coupled Fe ions with concentration of Fe more than 1%. The EPR spectra for QJ samples are very different from those for NL samples, exhibiting only rather intense FM EPR lines. The FM and EPR spectra in NL and/or QJ samples are found to vary strongly with differences in the surface morphology of nanoparticles. © 2014 Elsevier B.V