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Magnetoelectric (ME) materials displaying strong magnetically induced polarization have attracted considerable interest due to their potential applications in spintronics and various fast electrically controlled magnetic devices. CaMn$_7$O$_{12}$ (CMO) stands out for its giant spin-induced ferroelectric polarization. However, the origin of the induced electric polarization in CMO remains highly controversial and continues to be a subject of ongoing debate. In this paper, through room temperature X-ray powder diffraction (XRPD), temperature-dependent magnetic susceptibility, and thermally stimulated depolarizing current (TSDC) measurements, we provide experimental evidence for a route to tune the magnetically induced polarization by modifying the exchange-striction in CMO via Sr-doping. Our findings demonstrate that the large and broad current peaks observed near the first magnetic phase transition ($T_N1 \sim 90$ K) indicate contributions to the TSDC density from both extrinsic thermally stimulated depolarization processes and intrinsic pyroelectric current arising from magnetically induced polarization changes. We suggest that this reduction in induced electric polarization in CMO originates from the increase in the Mn$^{3+}$ -- O -- Mn$^{4+}$ bond angle due to Sr$^{2+}$ doping, weakening the exchange-striction interaction. Meanwhile, the Dzyaloshinskii-Moriya (DM) effect determines the direction of the induced electric polarization. Our result sheds light on understanding the intriguing giant-induced polarization in CMO and similar compounds with complex magnetic structures.

The Skyrmion Hall Effect (SkHE) observed in ferromagnetic (FM) and ferrimagnetic (FI) skyrmions traveling due to a spin-polarized current can be a problematic issue when it comes to technological applications. By investigating the properties of FI skyrmions in racetracks through computational simulations, we have described the nature of their movement based on the relative values of the exchange, Dzyaloshinskii-Moriya, and anisotropy coupling constants. Beyond that, using a design strategy, a magnetic channel-like nano-device is proposed in which a spin-polarized current protocol is created to successfully control the channel on which the skyrmion will travel without the adverse SkHE. Additionally, a simple adjustment in the current strength can modify the skyrmion position sideways between different parallel channels in the nanostripe., Comment: 10 pages, 9 figures

We report on the microwave, terahertz (THz), infrared and Raman spectroscopic studies of $BiMn_{7}O_{12}$ ceramics, shedding more light into the nature of two structural phase transitions and their possible relation with ferroelectricity in this compound. We observed a softening of one polar phonon in the THz range on cooling towards 460 and 300 K, i.e., temperatures at which $BiMn_{7}O_{12}$ undergoes subsequent structural phase transitions from monoclinic $\textit{I2/m}$ to polar monoclinic $\textit{Im}$ and triclinic $\textit{P1}$ phases. The soft phonon causes dielectric anomalies typical for displacive ferroelectric phase transitions. Microwave measurements performed at 5.8 GHz up to 400 K qualitatively confirmed not only the dielectric anomaly at 300 K, but also revealed two other weak dielectric anomalies near the magnetic phase transitions at 60 K and 28 K. This evidences the multiferroic nature of the low-temperature phases, although the relatively high conductivity in the kHz and Hz spectral range prevented us from directly measuring the permittivity and ferroelectric polarization. Some Raman modes sense the magnetic phase transitions occurring near 60 and 25 K, showing that spin-phonon coupling is relevant in this compound and in this temperature range. The deviation of the Mn-O stretching mode frequency from the anharmonic temperature behavior was successfully explained by the spin correlation function calculated from the magnetic contribution to the specific heat.

The correlation between static magnetoelectric coupling and magnetic structure was investigated in $TbMn_{0.98}Fe_{0.02}O_{3}$ with magnetic field up to 8 T and down to 2 K. Single-crystal neutron diffraction experiments reveal a substantial increase in the temperature dependence of the incommensurate modulation wave vector of the antiferromagnetic phase as the magnetic field strength increases. Magnetic field-dependent pyroelectric current measurements revealed significantly higher magnetoelectric coupling at magnetic fields below 4 T than in pure TbMnO3. This is due to the higher sensitivity of the incommensurably modulated cycloid structure to weak magnetic fields. Detailed analysis of our data confirmed that the ferroelectric polarization is induced by inverse Dzyaloshinskii-Moriya interaction for magnetic field strength up to 4 T, but at higher fields a departure from theoretical predictions is ascertained, giving evidence for an additional, as yet misunderstood, contribution to magnetoelectric coupling. It shows that a small 2% substitution of Mn3+ by Fe3+ has a strong impact on the magnetic structure, promoting the destabilization of the incommensurably modulated magnetic cycloidal structure of $TbMnO_{3}$ in a magnetic field above 5 T. We demonstrate that the magnetoelectric coupling magnitude can be tuned through suitable substitutional elements, even at low level, inducing local lattice distortions with different electronic and magnetic properties.

We report a comprehensive study of the low-level substitution of Mn$^{3+}$ by Fe$^{3+}$ effect on the static and dynamic magnetoelectric coupling in TbMn$_{1-x}$Fe$_x$O$_3$ ($x=0$, 0.02 and 0.04). The cationic substitution has a large impact on the balance between competitive magnetic interactions and, as a result, on the stabilization of the magnetic structures and ferroelectric phase at low temperatures. Low-lying electromagnon excitation is activated in the cycloidal modulated antiferromagnetic and ferroelectric phase in TbMnO$_3$, while it is observed up to TN in the Fe-substituted compounds, pointing for different mechanisms for static and dynamic magnetoelectric coupling. A second electrically active excitation near 40 cm$^{-1}$ is explained by means of Tb3+ crystal-field effects. This excitation is observed up to room temperature, and exhibits a remarkable 15 cm$^{-1}$ downshift on cooling in Fe-substituted compounds. Both electromagnon and crystal-field excitations are found to be coupled to the polar phonons with frequencies up to 250 cm$^{-1}$. Raman spectroscopy reveals a spin-phonon coupling below TN in pure TbMnO$_3$, but the temperature where the coupling start to be relevant increases with Fe concentration and reaches 100 K in TbMn$_{0.96}$Fe$_{0.04}$O$_3$. The anomalies in the T-dependence of magnetic susceptibility above TN are well accounted by spin-phonon coupling and crystal-field excitation, coupled to oxygen motions.

A realization of the composite Higgs scenario in the context of the effective model with the $SU(2)_L\times U(1)_R$ symmetric four-Fermi interactions proposed by Miransky, Tanabashi and Yamawaki is studied. The model implements Nambu's mechanism of dynamical electroweak symmetry breaking leading to the formation of $\bar tt$ and $\bar bb$ quark condensates. We explore the vacuum structure and spectrum of the model by using the Schwinger proper-time method. As a direct consequence of this mechanism, the Higgs acquires a mass in accord with its experimental value. The present prediction essentially differs from the known overestimated value, $m_\chi= 2m_t$, making more favourable the top condensation scenario presented here. The mass formulas for the members of the second Higgs doublet are also obtained. The Nambu sum rule is discussed. It is shown that the anomalous $U(1)_A$ symmetry breaking modifies this rule at next to leading order in $1/N_c$., Comment: 14 pages, version to appear in EPJC

This work reports on the pressure dependence of the octahedra tilts and mean Fe-O bond lengths in RFeO3 (R=Nd, Sm, Eu, Gd, Tb and Dy), determined through synchrotron X-ray diffraction and Raman scattering, and their role on the pressure induced phase transition displayed by all of these compounds. For larger rare-earth cations (Nd-Sm), both anti- and in-phase octahedra tilting decrease as pressure increases, whereas the reverse behavior is observed for smaller ones (Gd-Dy). EuFeO3 stands at the borderline, as the tilts are pressure independent. For the compounds where the tilts increase with pressure, the FeO6 octahedra are compressed at lower rates than for those ones exhibiting opposite pressure tilt dependence. The crossover between the two opposite pressure behaviors is discussed and faced with the rules grounded on the current theoretical approaches. The similarity of the pressure-induced isostructural insulator-to-metal phase transition, observed in the whole series, point out that the tilts play a minor role in its driving mechanisms. A clear relationship between octahedra compressibility and critical pressure is ascertained., Comment: 25 pages (including Supplemental Information), 12 figures and 4 tables

We analyze the thermodynamical properties of a system of strongly interacting particles at vanishing quark chemical potential in the framework of a recently developed extension of the Polyakov-Nambu-Jona-Lasinio Model. In addition to eight quark interactions terms, non-canonical terms which explicitly break chiral symmetry up to the same order in a $1/N_c$ expansion ($N_c$ number of colors) are included. A recently proposed Polyakov potential is considered and the results are compared to lattice QCD data resulting in a favorable scenario for the recent model variants., Comment: To appear in the proceedings of "8th International Conference on Quarks and Nuclear Physics (QNP2018)"

This paper presents a study on the reduction of the sampling frequency of the current signals of an induction motor, the reductions are performed by means time-decimation technique for digital signal processing. We have used the Fast Fourier Transform to obtain the fault signal spectrum of broken bars. The results have shown how the decimation technique significantly reduces the number of operations and the time required to calculate the Fast Fourier Transform without loss of information. This approach provides a better performance of embedded systems for fault diagnosis based on characteristic of amplitude signal modulation., Comment: in Portuguese

We analyse the effects of the light and strange current quark masses on the phase diagram of QCD at finite temperature and vanishing baryonic chemical potential, computing the speed of sound, the trace anomaly of the energy momentum tensor and the fluctuations and correlations of the conserved charges associated to baryonic, electric and strangeness numbers. The framework is a known extension of the three flavor Nambu Jona Lasinio model, which includes the full set of explicit chiral symmetry breaking interactions (ESB) up to the same order in large $N_c$ counting as the 't Hooft flavor mixing terms and eight quark interactions. It is shown that the ESB terms are relevant for the description of a soft region in the system's speed of sound and overall slope behavior of the observables computed. At the same time the role of the 8q interactions gets highlighted. The model extension with the Polyakov loop is considered and the results are compared to lattice QCD data., Comment: 15 pages, 10 figures

Extensions of the NJL model which go beyond the original 4-quark interaction, which drives the dynamical mass generation, have proven to be quite successful in describing low energy hadronic phenomenology. The inclusion of 8-quark interaction terms solved a metastability problem of the effective potential introduced by the inclusion of the 6-quark 't Hooft determinant term in the 3-flavor version of the model (needed to eliminate the unwanted U(1) axial symmetry) . This model, that has proven to be quite powerful and feature-rich, has been expanded to include all the spin-0 terms, without and with explicit chiral symmetry breaking, which are of the same order as the 't Hooft flavor determinant in a 1/Nc expansion resulting in an unprecedented success in reproducing the low lying scalar and pseudoscalar meson spectra. This success can be seen as a result of the inclusion of the full chiral symmetry breaking pattern. The two critical endpoints which are obtained in the temperature/chemical potential phase diagram are shifted to lower chemical potential and higher temperature when the effect of magnetic field is taken into account. For the studied magnetic field strengths (in the range $eH=0-0.4~GeV^2$) no significant extra transitions are seen to appear., Comment: Submitted for the proceedings of Hadron 2017 -XVII International Conference on Hadron Spectroscopy and Structure, September 25th-29th 2017, Salamanca, Spain

Here we study the resistive switching (RS) effect that emerges when ferroelectric BaTiO$_{3}$ (BTO) and few-layers MoSe$_{2}$ are combined in one single structure. The C-V loops reveal the ferroelectric nature of both Al/Si/SiO$_{x}$/BTO/Au and Al/Si/SiO$_{x}$/MoSe$_{2}$/BTO/Au structures and the high quality of the SiO$_{x}$/MoSe$_{2}$ interface in the Al/Si/SiOx/MoSe$_{2}$/Au structure. Al/Si/SiO$_{x}$/MoSe$_{2}$/BTO/Au hybrid structures show the electroforming free resistive switching that is explained on the basis of the modulation of the potential distribution at the MoSe$_{2}$/BTO interface via ferroelectric polarization flipping. This structure shows promising resistive switching characteristics with switching ratio of $\approx{}$10$^{2}$ and a stable memory window, which are highly required for memory applications.

A generalized 3 flavor Nambu-Jona--Lasinio Lagrangian including the explicit chiral symmetry breaking interactions which contribute at the same order in the large $1/N_c$ counting as the $U_A(1)$ 't Hooft flavor determinant is considered to obtain the mixing angles in the $\pi^0-\eta-\eta'$ system and related current quark mass ratios in close agreement with phenomenological values. At the same time an accurate ordering and magnitude of the splitting of states in the low lying pseudoscalar nonet is obtained., Comment: 6 pages, 4 tables, presented at the workshop "Excited QCD 2016", 05-12 March 2016, Costa da Caparica, Portugal. Submitted to Acta Phys. Pol. B

We present the magnetic phase diagram of TbMn1-xFexO3 substitutional solid solution in the whole concentration range 0 <= x <= 1 as determined from magnetization and specific heat measurements. We have found that the dominant magnetic ion in the concentration range 0 <= x < 0.3 is manganese, while iron ions do not create independent magnetic structure, but strongly affect magnetic properties of the parent compound by reducing transition to magnetically ordered state and transition into a cycloidal phase. The magnetism in the concentration range 0.3 < x <= 1 is driven by the Fe sublattice. The manganese ions again do not order in long range magnetic ordered state, but stabilize four different magnetic structures of Fe sublattice above 2 K. The magnetic ordering of Tb sublattice was observed only on parent compounds TbMnO3 and TbFeO3 and for doping level below 0.1, or over 0.9.

The present work reports the study of the optimized processing conditions of Bi0.9La0.1Fe0.9Mn0.1O3 thin films, grown by RF sputtering on platinum metalized silicon substrates. The combination of deposition at relatively low substrate temperature followed by adequate ex situ annealing leads to thin films with smooth surface morphology and the formation of a high-quality monophasic layer, with the (100)c preferable orientation. The annealed films show ferroelectric imprint.

This work addresses the effect of substituting Mn$^{3+}$ by Fe$^{3+}$ at the octahedral site of TbMnO$_3$ on the magnetic phase sequence, ferroelectric and magnetoelectric properties, keeping the Fe$^{3+}$ concentration below 5%. The temperature dependence of the specific heat, dielectric permittivity and electric polarization was studied as a function of Fe$^{3+}$ concentration and applied magnetic field. From the experimental results a strong decrease of the electric polarization with increasing Fe$^{3+}$ substitution is observed, vanishing above a concentration of 4%. However, within this range, a significant increase of the magnetic sensitivity of the electric polarization is obtained by increasing Fe$^{3+}$ concentration. Above that value, a non-polar, weak ferromagnetic phase emerges, in good agreement with the predictions of the Dzyalowshinskii-Moriya model. This behavior reveals the crucial effect of Fe$^{3+}$ substitution in octahedral sites on the magnetic phase sequence, polar and magnetoelectric behavior of the TbMn$_{1-x}$Fe$_x$O$_3$ system. From the results obtained in this work, it is understood that this behavior is not associated with the eg electronic configuration, but instead to the competition between ferromagnetic and antiferromagnetic interactions, which is very sensitive to both local fields and distortions., Comment: 11 pages, 4 figures

We report the analysis of radial characteristics of the flow of granular material through a conical hopper. The discharge is simulated for various orifice sizes and hopper opening angles. Velocity profiles are measured along two radial lines from the hopper cone vertex: along the main axis of the cone and along its wall. An approximate power law dependence on the distance from the orifice is observed for both profiles, although differences between them can be noted. In order to quantify these differences, we propose a Local Mass Flow index that is a promising tool in the direction of a more reliable classification of the flow regimes in hoppers.

The phase diagram of cold dense quark matter is studied using the 't Hooft extended Nambu--Jona-Lasinio Model applied to the light quark sector with a finite current mass for the strange quark (up and down are considered in the chiral limit). By relaxing the traditional uniformity assumptions and considering a modulated light quark condensate background we investigate the possible existence of non-uniform phases in this region of the phase diagram. The effects of changes in the coupling strengths of the model are studied and it is shown that the inclusion of flavour mixing combined with the finite current mass of the strange quark catalyses the appearance of the non-uniform phases, extending the domain for their existence., Comment: 5 pages, 4 figures. To appear in the Conference Proceedings for XI Quark Confinement and the Hadron Spectrum, St. Petersburg, Russia, September 8-12 2014

We present a systematic study of the structure and lattice dynamics at room temperature, and the phonon behavior at low temperatures in orthorhombic Gd$_{1-x}$Y$_{x}$MnO$_{3}$ manganites, with 0 $\leq$ x $\leq$ 0.4, using powder x-ray diffraction and Raman scattering. A thorough analysis towards the correlation between both structural and Raman modes parameters was undertaken. The data obtained at room temperature reveal structural distortions arising from the Jahn-Teller distortion and octahedra tilting. The Jahn-Teller distortion is apparently x-independent, while an increase of Mn-O1-Mn bond angle of about 0.5{\deg} could be ascertain when x changes from 0 to 0.4. Spin-phonon coupling was evidenced from the Raman results. The temperature dependence of the B1g in-plane O2 stretching mode of the MnO6 octahedron has revealed either a positive or negative shift regarding the pure anharmonic temperature dependence of the phonon frequency, which strongly depends on the Y-concentration. The frequency renormalization is explained in terms of a competition between ferro and antiferromagnetic interactions. The ratio between the spin-phonon coupling constant and the effective magnetic exchange integral per spin was determined from the renormalized wave number of the in-plane O2 stretching mode, associated with the spin-spin correlation function., Comment: Version with Supplemental Material

It is shown that the strange quark mass undergoes a first order transition in a generalized 3 flavor Nambu--Jona-Lasinio (NJL) Lagrangian which includes a complete set of explicit chiral symmetry breaking interactions. This transition occurs in a moderate chemical potential region $\mu \sim 400$ MeV, in addition to the usual chiral transition associated with the light quark sector. This favors the formation of stable strange quark matter at chemical potentials which are considerably lower than the ones discussed in the literature. The reason for this behavior is discussed., Comment: Presented at EEF70 - Workshop on Unquenched Hadron Spectroscopy: Non-Perturbative Models and Methods of QCD vs. Experiment, 6 pages 2 figures

The possible existence of non-uniform phases in cold dense quark matter in the light quark sector ($u$, $d$ and $s$) is addressed using the Nambu-Jona--Lasinio Model extended to include flavour-mixing 't Hooft determinant. The effect of changes in the coupling strengths of the model is discussed. It is seen that the inclusion of the strange sector catalyses the appearance of these non-uniform phases extending the domain for their appearance., Comment: To appear in the proceedings for Workshop on Unquenched Hadron Spectroscopy: Non-Perturbative Models and Methods of QCD vs. Experiment. 6 pages, 4 figures (minor revisions in this version)

It is shown that a first order transition associated with a jump in the strange quark mass appears in a generalized 3 flavour Nambu--Jona-Lasinio (NJL) treatment of quark matter. The generalization of the Lagrangian displays the complete set of spin 0 interactions at leading and subleading orders (LO and NLO) in $\frac{1}{N_c}$counting, including the recently derived NLO explicit chiral symmetry breaking interactions which are of the same order as the 't Hooft flavour determinant. The parameters of the model are tightly constrained by the low energy characteristics in both the pseudoscalar and scalar meson sectors. The transition occurs in a moderate chemical potential region ($\mu \simeq 400~\mathrm{MeV}$ for zero temperature) in addition to the usual chiral transition associated with the light quark sector. This feature has at its root the inclusion of the explicit chiral symmetry breaking interactions, which therefore can be seen to act as a catalyst in the production of strange quark matter when compared to the conventional version of the model that takes only into account the 't Hooft interaction in the NLO. It can be traced back to the effect of the interactions which do not violate the Okubo-Zweig-Iizuka rule (OZI), without which the empirical ordering of the scalars ($m_{K^\star}< m_{a_0}\approx m_{f_0}$) is not reproduced., Comment: 12 pages, 4 figures (11 subfigures). Revised and extended version. Accepted for publication in Phys. Rev. D

We report a high-pressure study of orthorhombic rare-earth manganites AMnO3 using Raman scattering (for A = Pr, Nd, Sm, Eu, Tb and Dy) and synchrotron X-ray diffraction (for A = Pr, Sm, Eu, and Dy). In all cases, a structural and insulator-to-metal transition was evidenced, with a critical pressure that depends on the A-cation size. We analyze the compression mechanisms at work in the different manganites via the pressure dependence of the lattice parameters, the shear strain in the a-c plane, and the Raman bands associated with out-of-phase MnO6 rotations and in-plane O2 symmetric stretching modes. Our data show a crossover across the rare-earth series between two different kinds of behavior. For the smallest A-cations, the compression is nearly isotropic in the ac plane, with presumably only very slight changes of tilt angles and Jahn-Teller distortion. As the radius of the A-cation increases, the pressure-induced reduction of Jahn-Teller distortion becomes more pronounced and increasingly significant as a compression mechanism, while the pressure-induced bending of octahedra chains becomes conversely less pronounced. We finally discuss our results in the light of the notion of chemical pressure, and show that the analogy with hydrostatic pressure works quite well for manganites with small A-cations but can be misleading with large A-cations., Comment: 23 pages, 11 figures

Epitaxial La0.7Sr0.3MnO3 (LSMO) thin films, with different thickness ranging from 20 nm up to 330 nm, were deposited on (100)-oriented strontium titanate (STO) substrates by pulsed laser deposition, and their structure and morphology characterized at room temperature. Magnetic and electric transport properties of the as-processed thin films reveal an abnormal behavior in the temperature dependent magnetization M(T) below the antiferrodistortive STO phase transition (TSTO) and also an anomaly in the magnetoresistance and electrical resistivity close to the same temperature. Up to 100 nm LSMO thin films, an in-excess magnetization and pronounced changes in the coercivity are evidenced, achieved through the interface-mediated magnetoelastic coupling with antiferrodistortive domain wall movement occurring below TSTO. Contrarily, for thicker LSMO thin films, above 100 nm, an in-defect magnetization is observed. This reversed behavior can be understood within the emergence in the upper layer of the film, observed by high resolution transmission electron microscopy, of a branched structure needed to relax elastic energy stored in the film which leads to randomly oriented magnetic domain reconstructions. For enough high-applied magnetic fields, as thermodynamic equilibrium is reached, a fully suppression of the anomalous magnetization occurs, wherein the temperature dependence of the magnetization starts to follow the expected Brillouin behavior., Comment: 15 pages, 9 figures

This work reports on magnetic, dielectric, thermodynamic and magnetoelectric properties of Gd$_{1-x}$Y$_{x}$MnO$_{3}$, with 0 \leq x \leq 0.4, with emphasis on the (x, T) phase diagram, towards unraveling the role of the driving mechanisms in stabilizing both magnetic and ferroelectric orderings. The (x, T) phase diagram reflects the effect of lattice distortions induced by the substitution of $Gd^{3+}$ ion by smaller $Y^{3+}$ ion, which gradually unbalances the antiferromagnetic against the ferromagnetic exchange interactions, enabling the emergence of ferroelectricity for higher concentrations of yttrium. For $x \leq 0.1$, the paramagnetic phase is followed by a presumably incommensurate collinear antiferromagnetic phase, then a weak ferromagnetic canted A-type antiferromagnetic ordering is established at lower temperatures.For $0.2 \leq x \leq 0.4$, a different phase sequence is obtained. The canted A-type antiferromagnetic arrangement is no more stable, and instead a pure antiferromagnetic ordering is stabilized below T$_{lock}$ $\approx$ 14 - 17 K, with an improper ferroelectric character. From these results, a cycloid modulated spin arrangement at low temperatures is proposed, accordingly to the inverse Dzyaloshinskii Moriya model. Anomalous temperature dependence of the dipolar relaxation energy and magnetization evidence for structural and magnetic changes occurring at $T* \approx 22 - 28 K$, for $0.1 \leq x \leq 0.4$., Comment: 26 pages, 9 figures. Results replaced in section 3d, and revised arguments. Number of figures reduced

It is shown that flavor mixing of the strange and light quarks allows for existence of a much larger baryonic chemical potential window for the formation of a stable dual chiral-wave state as compared to the well known two flavor case. In addition, strangeness catalyzes the occurrence of a new branch of non-homogeneous solutions at moderate densities. This case study is addressed at zero temperature within the SU(3) flavor Nambu-Jona-Lasinio model with the 't Hooft determinantal flavor mixing interaction. The modulation of the chiral condensates in the light quark sector is taken to be one-dimensional, while strangeness is embedded as a homogeneous condensate in the spontaneously broken phase of chiral symmetry. A finite current quark mass for the strange quark is incorporated, while the up and down current masses are set to zero. In that case the modulation considered provides an exact analytic solution for the system. Despite the simplicity of the \textit{ansatz}, the emerging phase diagram displays a very rich structure., Comment: 10 pages, 9 figure, in this version minor corrections, references added, version to appear in Phys. Rev. D

In this work, we analysed GdMnO3 magnetoelectric thin films prepared by a general sol-gel method. The film formation temperature is analysed by termogravimetric analysis, while the lattice parameters of the Pbnm orthorhombic films are determined from the analysis of the x-ray spectra. The x-ray results also reveal that GdMnO3 films are under compression along the b axis. The lattice dynamic analysis carried out by Raman spectroscopy confirms the formation of films with a Pbnm orthorhombic structure. Moreover, the analysis of the Raman spectra suggests that besides film-substrate interaction, texture and grain size influence can alters lattice dynamics relative to bulk ones. Magnetic measurements shows that the films response is different of the observed in ceramic and single crystal; mainly, in the shape and temperature where the transitions taking place. The magnetic study also reveals that GdMnO3 films are paramagnetic above 80 K, showing a ferromagnetic response at low temperatures (T=<15 K). The dielectric analysis carried out in the 850C annealed films shows the formation of a relaxation process at low temperature, which is associated with a polaronic process. Moreover, it is also observed a small anomaly at T~27 K that might be related with the magnetic transition taking place in this temperature range.

This work is focused on the phase diagrams and physical properties of Y-doped and Lu-doped EuMnO3. The differences in the corresponding phase boundaries in the (x,T) phase diagram could be overcome by considering a scaling of the Y3+ and Lu3+ concentrations to the tolerance factor. This outcome evidences that the tolerance factor is in fact a more reliable representative of the lattice deformation induced by doping. The normalization of the phase boundaries using the tolerance factor corroborates previous theoretical outcomes regarding the key role of competitive FM and AFM exchanges in determining the phase diagrams of manganite perovskites. Though, significant differences in the nature and number of phases at low temperatures and concentrations could not be explained by just considering the normalization to the tolerance factor. The vertical phase boundary observed just for Lu-doped EuMnO3, close to 10%Lu, is understood considering a low temperature Peierls-type spin-phonon coupling, which stabilizes the AFM4 phase in Lu-doped EuMnO3., Comment: 15 pages, 6 figures

Several relevant thermodynamic observables obtained within the (2+1) flavor and spin zero NJL and PNJL models with inclusion of the 't Hooft determinant and $8q$ interactions are compared with lattice-QCD (lQCD) results. In the case that a small ratio $R=\frac{\mu_B}{T_c}\sim 3$ at the critical end point (CEP) associated with the hadron gas to quark-gluon plasma transition is considered, combined with fits to the lQCD data of the trace anomaly[1], subtracted light quark condensate[1] and continuum extrapolated data of the light quark chiral condensate[2], a reasonable description for the PNJL model is obtained with a strength $g_1\sim 5...6 \times 10^3$ GeV$^{-8}$ of the $8q$ interactions. The dependence on the further model parameters is discussed., Comment: 6 pages, 6 figures, contribution to the International Meeting "Excited QCD", Peniche, Portugal, 06 - 12 May 2012"

We present a study of the effect of very high pressure on the orthorhombic perovskite GdMnO3 by Raman spectroscopy and synchrotron x-ray diffraction up to 53.2 GPa. The experimental results yield a structural and insulator-to-metal phase transition close to 50 GPa, from an orthorhombic to a metrically cubic structure. The phase transition is of first order with a pressure hysteresis of about 6 GPa. The observed behavior under very high pressure might well be a general feature in rare-earth manganites., Comment: 4 pages, 3 figures and 2 tables

In this work we investigate the magnetic field dependence of Ag octahedra rotation (tilt) and B2g symmetric stretching modes frequency at different temperatures. Our field-dependent Raman investigation at 10K is interpreted by an ionic displacive nature of the magnetically induced ferroelectric phase transition. The frequency change of the Ag tilt is in agreement with the stabilization of the Mn-Gd spin arrangement, yielding the necessary conditions for the onset of ferroelectricity on the basis of the inverse Dzyaloshinskii-Moriya interaction. The role of the Jahn-Teller cooperative interaction is also evidenced by the change of the B2g mode frequency at the ferroelectric phase transition. This frequency change allows estimating the shift of the oxygen position at the ferroelectric phase transition and the corresponding spontaneous polarization of 480 {\mu}C/m2, which agrees with earlier reported values in single crystals. Our study also confirms the existence of a large magnetic hysteresis at the lowest temperatures, which is a manifestation of magnetrostiction., Comment: 5 pages, 3 figures

A study of the foating of a circular cone shaped buoy in an ideal fluid has revealed some new interesting results. Using reduced variables it is shown, that at a crossover value (3/4) of the ratio of the specific masses of the fluid and of the buoy, the anharmonicity of the oscillation is the highest and that, unexpectedly, above this crossover value the normalized period is constant.

The phase diagram at finite temperature and chemical potential for the Polyakov-NJL model with eight quark interactions is reviewed for the SU(3) flavor case., Comment: Prepared for the Internationsal Symposium on Multiparticle Dynamics 2011 (ISMD2011), 6 figures

We study a generalization of the Wolf-Villain (WV) interface growth model based on a probabilistic growth rule. In the WV model, particles are randomly deposited onto a substrate and subsequently move to a position nearby where the binding is strongest. We introduce a growth probability which is proportional to a power of the number $n_i$ of bindings of the site $i$: $p_i\propto n_i^\nu$. Through extensively simulations, in $(1+1)$-dimensions, we find three behavior depending of the $\nu$ value: {\it i}) if $\nu$ is small, a crossover from the Mullins-Hering to the Edwards-Wilkinson (EW) universality class; {\it ii}) for intermediate values of $\nu$, a crossover from the EW to the Kardar-Parisi-Zhang (KPZ) universality class; {\it iii}) and, finally, for large $\nu$ values, the system is always in the KPZ class. In $(2+1)$-dimensions, we obtain three different behaviors: {\it i}) a crossover from the Villain-Lai-Das Sarma to the EW universality class, for small $\nu$ values; {\it ii}) the EW class is always present, for intermediate $\nu$ values; {\it iii}) a deviation from the EW class is observed, for large $\nu$ values., Comment: 9 pages, 6 figures, published in JSTAT

Several advantages in the use of a Pauli-Villars regularization procedure in extended Nambu--Jona-Lasinio models with Polyakov loop are discussed., Comment: 4 pages, 4 figures prepared for the proceedings of 6th International Conference on Physics and Astrophysics of Quark Gluon Plasma (ICPAQGP 2010)

The extension of the Nambu-Jona-Lasino Model with six and eight quark interactions to include the Polyakov loop is analysed. Several interesting features are determined to be an effect of the choice of the regularization procedure. The use of a Pauli-Villars covariant regularization enables a coherent and correct description of several quantities., Comment: 3 pages, 6 figures, to appear in the conference proceedings for Quark Confinement and the Hadron Spectrum IX, August 30- September 3 2010, Madrid (Spain)

An attempt is made to resolve certain incongruities within the Nambu - Jona-Lasinio (NJL) and Polyakov loop extended NJL models (PNJL) which currently are used to extract the thermodynamic characteristics of the quark-gluon system. It is argued that the most attractive resolution of these incongruities is the possibility to obtain the thermodynamic potential directly from the corresponding extremum conditions (gap equations) by integrating them, an integration constant being fixed in accordance with the Stefan-Boltzmann law. The advantage of the approach is that the regulator is kept finite both in divergent and finite valued integrals at finite temperature and chemical potential. The Pauli-Villars regularization is used, although a standard 3D sharp cutoff can be applied as well., Comment: 16 pages, 5 figures, extended version, title changed

We report an investigation of hexagonal Y_(1-x)Eu_xMnO_3 ceramics with x=0, 0.1 and 0.2 using infrared and THz spectroscopies in the temperature range between 5 and 900 K. The temperature dependence of the THz permittivity reveals a kink near the antiferromagnetic phase transition temperature T_N ~ 70 K giving evidence of a strong spin-lattice coupling. Below T_N two absorption peaks were revealed in the THz spectra close to 43 and 73 cm-1. While the first peak corresponds to a sharp antiferromagnetic resonance exhibiting softening on heating towards TN, the second one may be attributed to an impurity mode or a multiphonon absorption peak. High-temperature THz spectra measured up to 900 K reveal only small gradual increase of the permittivity in agreement with a weak phonon softening observed in the infrared reflectance spectra upon heating. This corresponds to an improper ferroelectric character of the phase transition proposed from first principle calculations by Fennie and Rabe [Phys. Rev. B 72 (2005), pp. 100103(R)]., Comment: Phase Transitions, accepted

Hydroxyapatite (HAp) [Ca10(PO4)6(OH)2] nanorods were synthesized using a surfactant templating method, with cetyltrimethylammonium bromide (CTAB) micelles acting as template for HAp growth. The effects of the sintering temperature on the morphological and crystallographic characteristics and on chemical composition of the "as-prepared" structures are discussed. The experimental results show that low heat-treatment temperatures are preferred in order to obtain high quality nanorods, with diameters ranging between 20 nm and 50 nm. High heat-treatment temperatures enhance the thermal decomposition of HAp into other calcium phosphate compounds, and the sintering of particles into micrometer ball-like structures. The stability of aqueous suspensions of HAp nanorods is also discussed., Comment: 6 figures, one table

This work reports an experimental investigation of the magneto-elastic coupling and polarization character of magnetic phases of the orthorhombic Eu1-xYxMnO3 system at low temperatures. The temperature dependence of the polarization reversal curves clearly reveals the existence of a reentrant improper ferroelectric phase for x = 0.2 and 0.3. Although a ferroelectric phase is also stable for x = 0.4, we have no experimental evidence that it vanishing at finite temperatures. From these results and those obtained from other experimental techniques, the corresponding (x,T) phase diagram was traced, yet yielding significant differences with regard to previous reports. An expressive magneto-elastic coupling is revealed by changes observed in both Mn-O bond lengths and Mn-O1-Mn bond angle at the magnetic phase transitions, obtained by temperature dependence of synchrotron x-ray diffraction experiments. Furthermore, signatures of the lattice deformations across the magnetic phase transitions were evidenced by anomalies in the temperature dependence of the lattice mode involving rotations of the MnO6 octahedra. These anomalies confirm the important role of the spin-phonon coupling in these materials., Comment: 12 Figures, 2 Tables

It is shown that the endpoint of the first order transition line which merges into a crossover regime in the phase diagram of the Nambu--Jona-Lasinio model, extended to include the six-quark 't Hooft and eight-quark interaction Lagrangians, is pushed towards vanishing chemical potential and higher temperatures with increasing strength of the OZI-violating eight-quark interactions. We clarify a connection between the location of the endpoint in the phase diagram and the mechanism of chiral symmetry breaking at the quark level. Constraints on the coupling strengths based on groundstate stability and physical considerations are explained., Comment: 5 pages, 3 figures, prepared for the proceedings of Hadron 2009 - XIII International Conference on Hadron Spectroscopy, November 29 - December 4, Florida State University (USA)

This is the first paper of a series presenting a Spheroid's Panchromatic Investigation in Different Environmental Regions (SPIDER). The sample of spheroids consists of 5,080 bright (Mr<-20) Early-Type galaxies (ETGs), in the redshift range of 0.05 to 0.095, with optical (griz) photometry and spectroscopy from SDSS-DR6 and Near-Infrared (YJHK) photometry from UKIDSS-LAS (DR4). We describe how homogeneous photometric parameters (galaxy colors and structural parameters) are derived using grizYJHK wavebands. We find no systematic steepening of the CM relation when probing the baseline from g-r to g-K, implying that internal color gradients drive most of the mass-metallicity relation in ETGs. As far as structural parameters are concerned we find that the mean effective radius of ETGs smoothly decreases, by ~30%, from g through K, while no significant dependence on waveband is detected for the axis ratio, Sersic index, and a4 parameters. Also, velocity dispersions are re-measured for all the ETGs using STARLIGHT and compared to those obtained by SDSS. We compare our (2DPHOT) measurements of total magnitude, effective radius, and mean surface brightness with those obtained as part of the SDSS pipeline (Photo). Significant differences are found and reported, including comparisons with a third and independent part. A full characterization of the sample completeness in all wavebands is presented, establishing the limits of application of the characteristic parameters presented here for the analysis of the global scaling relations of ETGs., Comment: Accepted for Publication in MNRAS

We present the results obtained in the three-flavour ($N_f=3$) Nambu--Jona-Lasinio model which is extended by the $U(1)_A$ breaking six-quark 't Hooft interaction and eight-quark interactions. We address the problem of stability, and some phenomenological consequences of the models with multi-quark interactions., Comment: 4 pages, prepared for the "Mini-Workshop Bled 2009: Problems in multi-quark states"

Eu1-xYxMnO3 exhibits, unlike other magnetoelectric systems, very distinctive features. Its magnetoelectric properties is driven by the magnetic spin of the Mn3+ ion, but they can be drastically changed by varying the content of Y3+, which it does not carry any magnetic moment. Though the x = 0.40 composition has been studied extensively, some basic questions still remain to be thoroughly understood. Thus, this work is aimed at studying some of its polar properties and their magnetic field dependence as well. The experimental results here reported have shown that this material is very easily polarisable under external electric fields, and so, whenever the polarization is obtained from time integration of the displacement currents, an induced polarization is superposed to the spontaneous one, eventually masking the occurrence of ferroelectricity. We have found clear evidence for the influence of a magnetic field in the polar properties of Eu0.6Y0.4MnO3. The study of electric polarization of Eu0.6Y0.4MnO3 under an external magnetic field yields a value with the same order of magnitude of the remanent polarization determined from polarization reversal experiments. The comparison of the magnetic induced changes on the polarization obtained in polycrystalline samples and single crystals confirms the threshold magnetic field value for the polarization rotation from the a- to the c-direction, and evidencing the importance of the granular nature of the samples in the polar response to magnetic field., Comment: 28 pages, 12 figures. Accepted for publication in J. Phys.: Condens. Matter

We present a new sample of 25 fossil groups (FGs) at z < 0.1, along with a control sample of seventeen bright ellipticals located in non-fossil systems. Both the global properties of FGs (e.g. X-ray luminosity) as well as the photometric properties (i.e. isophotal shape parameter, a4) and spectroscopic parameters (e.g. the alpha-enhancement) of their first-ranked ellipticals are consistent with those of the control sample. This result favors a scenario where FGs are not a distinct class of systems, but rather a common phase in the life of galaxy groups. We also find no evidence for an evolutionary sequence explaining the formation of galaxies in fossil systems through the merging of galaxies in compact groups., Comment: 4 pages, 3 figures, to appear in the ASP Conference Series Proceedings of "Galaxies in Isolation: Exloring Nature vs. Nurture", Granada, 2009

We use SDSS data to investigate the scaling relations of 127 NoSOCS and 56 CIRS galaxy clusters at low redshift ($z \le 0.10$). We show that richness and both optical and X-ray luminosities are reliable mass proxies. The scatter in mass at fixed observable is $\sim$ 40%, depending on the aperture, sample and observable considered. For example, for the massive CIRS systems $\sigma_{lnM500|N500}$ = 0.33 $\pm$ 0.05 and $\sigma_{lnM500|Lx}$ = 0.48 $\pm$ 0.06. For the full sample $\sigma_{lnM500|N500}$ = 0.43 $\pm$ 0.03 and $\sigma_{lnM500|Lx}$ = 0.56 $\pm$ 0.06. We estimate substructure using two and three dimensional optical data, verifying that substructure has no significant effect on the cluster scaling relations (intercepts and slopes), independent of which substructure test we use. For a subset of twenty-one clusters, we estimate masses from the M-T$_X$ relation using temperature measures from BAX. The scaling relations derived from the optical and X-ray masses are indeed very similar, indicating that our method consistently estimates the cluster mass and yields equivalent results regardless of the wavelength from which we measure mass. For massive systems, we represent the mass-richness relation by a function with the form ${\rm ln (M_{200}) = A + B \times ln(N_{200}/60)}$, with M$_{200}$ being expressed in units of 10$^{14}$ M$_{\odot}$. Using the virial mass, for CIRS clusters, we find A = (1.39 $\pm$ 0.07) and B = (1.00 $\pm$ 0.11). The relations based on the virial mass have a scatter of $\sigma_{lnM200|N200}$ = 0.37 $\pm$ 0.05, while $\sigma_{lnM200|N200}$ = 0.77 $\pm$ 0.22 for the caustic mass and $\sigma_{lnM200|N200}$ = 0.34 $\pm$ 0.08 for the temperature based mass (abridged)., Comment: 27 pages, 22 figures, 12 tables, Accepted to MNRAS

To clarify the controversy concerning the ferroelectricity of the lower temperature magnetic phases of Eu0.8Y0.2MnO3, hence its multiferroic character, we have studied in detail the temperature dependence of the electric polarization. The existence of a spontaneous polarization in 30K < T < 22K, provides clear evidence for the ferroelectric character of the re-entrant magnetic phase, stable in that temperature range. Both lower temperature magnetic phases allow easily-induced electric polarization, which actually mask any spontaneous polarization., Comment: 11 pages, 4 figures, submitted to Phys. Rev. Letters

In this work we present a detailed study of the structural and lattice dynamic properties of Y-doped EuMnO3 ceramics (Eu1-xYxMnO3, with 0

We present the complete galaxy cluster catalog from the Northern Sky Optical Cluster Survey, a new, objectively defined catalog of candidate galaxy clusters at z<0.25 drawn from the Digitized Second Palomar Observatory Sky Survey (DPOSS). The data presented here cover the Southern Galactic Cap, as well as the less-well calibrated regions of the Northern Galactic Cap. In addition, due to improvements in our cluster finder and measurement methods, we provide an updated catalog for the well-calibrated Northern Galactic Cap region previously published in Paper II. The complete survey covers 11,411 square degrees, with over 15,000 candidate clusters. We discuss improved photometric redshifts, richnesses and optical luminosities which are provided for each cluster. A variety of substructure measures are computed for a subset of over 11,000 clusters. We also discuss the derivation of dynamical radii r_200 and its relation to cluster richness. A number of consistency checks between the three areas of the survey are also presented, demonstrating the homogeneity of the catalog over disjoint sky areas. We perform extensive comparisons to existing optically and X-ray selected cluster catalogs, and derive new X-ray luminosities and temperatures for a subset of our clusters. We find that the optical and X-ray luminosities are well correlated, even using relatively shallow ROSAT All Sky Survey and DPOSS data. This survey provides a good comparison sample to the MaxBCG catalog based on Sloan Digital Sky Survey Data, and complements that survey at low redshifts 0.07

We use SDSS-DR4 photometric and spectroscopic data out to redshift z~0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of twenty-five fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample and the main pitfalls are discussed. The spatial density of FGs, estimated via the V/V_ MAX} test, is 2.83 x 10^{-6} h_{75}^3 Mpc^{-3} for L_x > 0.89 x 10^42 h_{75}^-2 erg/s consistent with Vikhlinin et al. (1999), who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same dataset. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a$_{4}$ and internal color gradients. Furthermore, examination of stellar populations shows that our twenty-five FGs have similar ages, metallicities, and $\alpha$-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the Universe., Comment: 18 pages, Accepted to AJ