Magnetic structure of the field-induced multiferroic GdFe3(BO3)4

We report a magnetic x-ray scattering study of the field-induced multiferroic GdFe3(BO3)4. Resonant x-ray magnetic scattering at the Gd LII,III edges indicates that the Gd moments order at TN ~ 37 K. The magnetic structure is incommensurate below TN, with the incommensurability decreasing monotonically with decreasing temperature until a transition to a commensurate magnetic phase is observed at T ~ 10 K. Both the Gd and Fe moments undergo a spin reorientation transition at TSR ~ 9 K such that the moments are oriented along the crystallographic c axis at low temperatures. With magnetic field applied along the a axis, our measurements suggest that the field-induced polarization phase has a commensurate magnetic structure with Gd moments rotated ~45 degrees toward the basal plane, which is similar to the magnetic structure of the Gd subsystem observed in zero field between 9 and 10 K, and the Fe subsystem has a ferromagnetic component in the basal plane.Comment: 27 pages, 7 figures, to appear in Phys. Rev.

AN ANALYSIS OF REGIONAL ECONOMIC GROWTH AND CAPITAL EXPENDITURE ON SELF-GENERATED REVENUE IN SUPIORI REGENCY

The purpose of this research is to evaluate the effect of the economic growth and the capital expenditures on self-generated revenue of Supiori Regency during 2008 to 2014 partially and simultaneously. This research was a causative research aims to test hypotheses and explain the phenomenon in relation of the research variables. Data collected was from secondary sources such as government publication documents comprise of economic growth information, the amount of capital expenditures, and the region self-generated revenue. The population in this study was Audited Budget Realization Report and economic growth of Supiori Regency and Papua Province from 2008 to 2014. While the sample consisted of economic growth information based on accepted prices, capital expenditures and self-generated revenue of Supiori Regency and Papua province from 2008 to 2014. All these data being analyzed used a classical assumption test and path analysis. According to the analysis, the results showed that the economic growth of Supiori Regency has a positive and significant effect on self-generated revenue of Supiori partially and simultaneously in 2008 to 2014. While the allocation for capital expenditures from 2008 to 2014 has positive effect but not significant on the regional self-generated revenue in Supiori partially and simultaneously. Also, the allocation of capital expenditure and the economic development from 2008 to 2014 have positive but not significant effect on the regional self-generated revenue in Supiori partially and simultaneously. As can be seen from the pattern of correlation from each variables, this study concluded that the capital expenditures was not the intervening variables to the progress of the region self-generated revenue in Supiori Regency. Keywords : Self-Generated Revenue, Economic Growth, Capital Expenditur

Optical spectra, crystal-field parameters, and magnetic susceptibility of the new multiferroic NdFe3(BO3)4

We report high-resolution optical absorption spectra for NdFe3(BO3)4 trigonal single crystal which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN = 33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g-factors. In particular, the values g(perpendicular) = 2.385, g(parallel) = 1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc=7.88 T and |JFN|= 0.48 K for the values of the local effective magnetic field at liquid helium temperatures at the Nd3+ site and the Nd - Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check reliability of our set of crystal field parameters we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn = -6.25 K (intra-chain interactions) and Jnnn = -1.92 K (inter-chain interactions) obtained from fitting agree well with the experimental data.Comment: 13 pages, 8 figures, 2 table

Evidence for a collinear easy-plane magnetic structure of multiferroic EuF e3(B O3)4: Spectroscopic and theoretical studies

© 2016 American Physical Society.We performed high-resolution polarized optical transmission spectroscopy and theoretical studies of multiferroic EuFe3(BO3)4 single crystals in the three phases: paramagnetic R32(T>Ts=84K) and P3121(Ts>T>TN=34K), and antiferromagnetic (T<TN) ones. The analysis of the spectra reveals interesting details of the magnetic structure, namely, a collinear arrangement of the iron magnetic moments along the C2 symmetry axis in the ab crystallographic plane of EuFe3(BO3)4 below TN. Spectral signatures of the phase transitions and the spin-phonon interaction are observed and discussed. Reliable crystal-field and exchange-interaction parameters are obtained and used to model the magnetic susceptibility of the compound. The results of detailed calculations of the electric polarization of EuFe3(BO3)4 in the R32 phase are presented, and mechanisms of the magnetoelectric response are discussed. We detect a strong effect of impurities (that enter the crystal from a flux in the course of the crystal growth) on the structural phase-transition temperature and demonstrate a coexistence of both R32 and P3121 phases down to the lowest temperatures in a EuFe3(BO3)4 crystal grown with the Bi2Mo3O12 based flux, due to inhomogeneous distribution of impurity Bi3+ ions. Our study can be considered as a demonstration of the abilities of optical spectroscopy in delivering new information on a magnetic compound, even in the case when other methods fail

Optical spectra, crystal-field parameters, and magnetic susceptibility of multiferroic Nd Fe3 (B O3) 4

We report high-resolution optical absorption spectra for Nd Fe3 (B O3) 4 trigonal single crystal, which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN =33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g factors. In particular, the values g =2.385 and g =1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc =7.88 T and JFN =0.48 K for the values of the local effective magnetic field at liquid-helium temperatures at the Nd3+ site and the Nd-Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check the reliability of our set of crystal-field parameters, we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn =-6.25 K (intrachain interactions) and Jnnn =-1.92 K (interchain interactions) obtained from fitting agree well with the experimental data. © 2007 The American Physical Society

Evidence for a collinear easy-plane magnetic structure of multiferroic EuF e3(B O3)4: Spectroscopic and theoretical studies

© 2016 American Physical Society.We performed high-resolution polarized optical transmission spectroscopy and theoretical studies of multiferroic EuFe3(BO3)4 single crystals in the three phases: paramagnetic R32(T>Ts=84K) and P3121(Ts>T>TN=34K), and antiferromagnetic (T<TN) ones. The analysis of the spectra reveals interesting details of the magnetic structure, namely, a collinear arrangement of the iron magnetic moments along the C2 symmetry axis in the ab crystallographic plane of EuFe3(BO3)4 below TN. Spectral signatures of the phase transitions and the spin-phonon interaction are observed and discussed. Reliable crystal-field and exchange-interaction parameters are obtained and used to model the magnetic susceptibility of the compound. The results of detailed calculations of the electric polarization of EuFe3(BO3)4 in the R32 phase are presented, and mechanisms of the magnetoelectric response are discussed. We detect a strong effect of impurities (that enter the crystal from a flux in the course of the crystal growth) on the structural phase-transition temperature and demonstrate a coexistence of both R32 and P3121 phases down to the lowest temperatures in a EuFe3(BO3)4 crystal grown with the Bi2Mo3O12 based flux, due to inhomogeneous distribution of impurity Bi3+ ions. Our study can be considered as a demonstration of the abilities of optical spectroscopy in delivering new information on a magnetic compound, even in the case when other methods fail

Optical spectra, crystal-field parameters, and magnetic susceptibility of multiferroic Nd Fe3 (B O3) 4

We report high-resolution optical absorption spectra for Nd Fe3 (B O3) 4 trigonal single crystal, which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN =33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g factors. In particular, the values g =2.385 and g =1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc =7.88 T and JFN =0.48 K for the values of the local effective magnetic field at liquid-helium temperatures at the Nd3+ site and the Nd-Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check the reliability of our set of crystal-field parameters, we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn =-6.25 K (intrachain interactions) and Jnnn =-1.92 K (interchain interactions) obtained from fitting agree well with the experimental data. © 2007 The American Physical Society

Optical spectra, crystal-field parameters, and magnetic susceptibility of multiferroic Nd Fe3 (B O3) 4

We report high-resolution optical absorption spectra for Nd Fe3 (B O3) 4 trigonal single crystal, which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN =33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g factors. In particular, the values g =2.385 and g =1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc =7.88 T and JFN =0.48 K for the values of the local effective magnetic field at liquid-helium temperatures at the Nd3+ site and the Nd-Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check the reliability of our set of crystal-field parameters, we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn =-6.25 K (intrachain interactions) and Jnnn =-1.92 K (interchain interactions) obtained from fitting agree well with the experimental data. © 2007 The American Physical Society

Optical spectra, crystal-field parameters, and magnetic susceptibility of multiferroic Nd Fe3 (B O3) 4

We report high-resolution optical absorption spectra for Nd Fe3 (B O3) 4 trigonal single crystal, which is known to exhibit a giant magnetoelectric effect below the temperature of magnetic ordering TN =33 K. The analysis of the temperature-dependent polarized spectra reveals the energies and, in some cases, symmetries and exchange splittings of Nd3+ 84 Kramers doublets. We perform crystal-field calculations starting from the exchange-charge model, obtain a set of six real crystal-field parameters, and calculate wave functions and magnetic g factors. In particular, the values g =2.385 and g =1.376 were found for the Nd3+ ground-state doublet. We obtain Bloc =7.88 T and JFN =0.48 K for the values of the local effective magnetic field at liquid-helium temperatures at the Nd3+ site and the Nd-Fe exchange integral, respectively, using the experimentally measured Nd3+ ground-state splitting of 8.8 cm-1. To check the reliability of our set of crystal-field parameters, we model the magnetic susceptibility data from literature. A dimer containing two nearest-neighbor iron ions in the spiral chain is considered to partly account for quasi-one-dimensional properties of iron borates, and then the mean-field approximation is used. The results of calculations with the exchange parameters for Fe3+ ions Jnn =-6.25 K (intrachain interactions) and Jnnn =-1.92 K (interchain interactions) obtained from fitting agree well with the experimental data. © 2007 The American Physical Society